View Filing Data

Product Revenues [Member] | Customer Two [Member]

55.00%

Summary Of Significant Accounting Policies [Line Items]

Product Revenues [Member] | Customer Three [Member]

29.00%

Summary Of Significant Accounting Policies [Line Items]

Accounts Receivable | Customer One [Member]

16.00%

Summary Of Significant Accounting Policies [Line Items]

Accounts Receivable | Customer Two [Member]

58.00%

Summary Of Significant Accounting Policies [Line Items]

Accounts Receivable | Customer Three [Member]

30.00%

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

12.00%

Minimum [Member]

Accounts receivable payment term

30 days

Maximum [Member]

Summary Of Significant Accounting Policies [Line Items]

Accounts receivable payment term

45 days

[1]

Gain From Sale of Priority Review Voucher - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Jun. 30, 2017
Gain From Sale Of Intangible Asset [Line Items]
Gain from sale of PRV asset		$ 125,000
Gilead [Member]
Gain From Sale Of Intangible Asset [Line Items]
Gain from sale of PRV asset	$ 125,000

Assets Measured and Carried at Fair Value (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 197,893	$ 207,915
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	40,261	1,147
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	58,428	69,304
Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	79,254	105,287
Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	19,302	20,834
Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	648	11,343
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	40,909	12,490
Level 1 [Member] \| Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	40,261	1,147
Level 1 [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	648	11,343
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	156,984	195,425
Level 2 [Member] \| Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	58,428	69,304
Level 2 [Member] \| Government and Government Agency Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	79,254	105,287
Level 2 [Member] \| Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets	$ 19,302	$ 20,834

Cash, Cash Equivalents and Short-Term Investments - Additional Information (Detail)	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Weighted average maturity period of available-for-sale securities	7 months	4 months

Summary of Company Cash, Cash Equivalents and Short-term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	$ 300,984	$ 317,965
Cash, cash equivalents and short-term investments, Gross unrealized losses	(38)	(120)
Cash, cash equivalents and short-term investments, Fair market value	300,946	317,845
Cash and Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	143,962	122,420
Cash, cash equivalents and short-term investments, Fair market value	143,962	122,420
Commercial Paper [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	58,443	69,355
Cash, cash equivalents and short-term investments, Gross unrealized losses	(15)	(51)
Cash, cash equivalents and short-term investments, Fair market value	58,428	69,304
Government and Government Agency Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	79,273	105,340
Cash, cash equivalents and short-term investments, Gross unrealized losses	(19)	(53)
Cash, cash equivalents and short-term investments, Fair market value	79,254	105,287
Corporate Bonds [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	19,306	20,850
Cash, cash equivalents and short-term investments, Gross unrealized losses	(4)	(16)
Cash, cash equivalents and short-term investments, Fair market value	19,302	20,834
Cash and Cash Equivalents [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	168,352	122,420
Cash, cash equivalents and short-term investments, Gross unrealized losses	(4)
Cash, cash equivalents and short-term investments, Fair market value	168,348	122,420
Short-term Investments [Member]
Cash and Cash Equivalents [Line Items]
Cash, cash equivalents and short-term investments, Amortized cost	132,632	195,545
Cash, cash equivalents and short-term investments, Gross unrealized losses	(34)	(120)
Cash, cash equivalents and short-term investments, Fair market value	$ 132,598	$ 195,425

Accounts Receivable and Reserves for Product Sales - Summary of Components of Accounts Receivable (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Receivables Net Current [Abstract]
Product sales, net of reserves	$ 16,862	$ 4,002
Government contract receivables	929	1,226
Total accounts receivable	$ 17,791	$ 5,228

Accounts Receivable and Reserves for Product Sales - Summary of Change in Reserves for Discounts and Allowances (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	$ 306
Provision	3,664
Payments/credits	(1,865)
Balance, as of June 30, 2017	2,105
Chargebacks [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	1
Provision	1,413
Payments/credits	(1,173)
Balance, as of June 30, 2017	241
Rebates [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	238
Provision	1,901
Payments/credits	(405)
Balance, as of June 30, 2017	1,734
Other Accruals [Member]
Accounts Notes And Loans Receivable [Line Items]
Balance, as of December 31, 2016	67
Provision	350
Payments/credits	(287)
Balance, as of June 30, 2017	$ 130

Accounts Receivable and Reserves for Product Sales - Summary of Total Reserves Included in Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Receivables Net Current [Abstract]
Reduction to accounts receivable	$ 241	$ 1
Component of accrued expenses	1,864	305
Total reserves	$ 2,105	$ 306

Inventory - Summary of Components of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 27,814	$ 9,531
Work in progress	13,780	3,175
Finished goods	160	107
Total inventory	$ 41,754	$ 12,813

Asset Held for Sale - Additional Information (Detail) - USD ($)	3 Months Ended
	Jun. 30, 2017	Mar. 31, 2017
Asset Held For Sale Current [Abstract]
Net book value of airport facility reclassified as an assets held for sale, current	$ 1,529,000	$ 1,500,000
Changes to assets held for sale	$ 0

Summary of Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Prepaid Expense And Other Assets Current [Abstract]
Manufacturing-related deposits and prepaids	$ 21,035	$ 23,604
Prepaid clinical and preclinical expenses	3,974	1,225
Other prepaids	2,416	1,152
Other	1,140	914
Total other current assets	$ 28,565	$ 26,895

Summary of Other Non-current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Prepaid Expense And Other Assets Noncurrent [Abstract]
Prepaid clinical expenses	$ 7,056	$ 3,725
Manufacturing-related deposits	4,284
Other	242	242
Total other non-current assets	$ 11,582	$ 3,967

Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued clinical and preclinical costs	$ 11,148	$ 10,033
Accrued employee compensation costs	8,035	8,748
Accrued contract manufacturing costs	5,886	4,673
Accrued professional fees	5,012	2,799
Accrued EXONDYS 51 litigation and license charges	2,839
Product revenue related reserves	1,864	305
Accrued research costs	547	1,186
Other	3,848	3,272
Total accrued expenses	$ 39,179	$ 31,016

Restructuring - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Apr. 30, 2017	Dec. 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring expenses			$ 2,524	$ 626	$ 2,760	$ 1,159
Facility Closing [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses			$ 100		$ 2,300
Workforce Reduction [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses				$ 500		$ 1,100
Corvallis Plan [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring, initiation date					2016-03
Restructuring, completion date					Jun. 30, 2017
Minimum lease payment obligation					$ 5,600
Corvallis Plan [Member] \| Facility Closing [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring expenses	$ 2,300	$ 1,500

Summary of Restructuring Expenses by Function (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses, Cash	$ 2,524	$ 536	$ 2,760	$ 924
Total restructuring expenses, Non-cash		90		235
Total restructuring expenses	2,524	626	2,760	1,159
Research and Development [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses, Cash	104	463	174	820
Total restructuring expenses, Non-cash		48		193
Total restructuring expenses	104	511	174	1,013
Selling, General and Administrative [Member]
Restructuring Cost And Reserve [Line Items]
Total restructuring expenses, Cash	2,420	73	2,586	104
Total restructuring expenses, Non-cash		42		42
Total restructuring expenses	$ 2,420	$ 115	$ 2,586	$ 146

Summary of Restructuring Reserve (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Restructuring And Related Activities [Abstract]
Restructuring reserve beginning balance	$ 1,588
Restructuring expenses incurred during the period	2,760	$ 3,651
Amounts paid during the period	(850)	(2,063)
Restructuring reserve ending balance	$ 3,498	$ 1,588

Summary of Stock Awards Granted (Detail) - $ / shares

3 Months Ended

6 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Jun. 30, 2017

Jun. 30, 2016

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grants, Stock options

3,579,467

^[1]

7,600

4,456,959

^[1]

1,213,376

Weighted Average Grant Date Fair Value, Stock options

$ 13.64

$ 15.61

$ 14.16

$ 11.94

Restricted Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grants, Restricted stock units and awards

20,000

181,029

^[2]

Weighted Average Grant Date Fair Value, Restricted stock units and awards

$ 36.26

$ 33.03

Restricted Stock Awards (RSAs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Grants, Restricted stock units and awards

335,000

^[3]

341,500

^[3]

25,775

Weighted Average Grant Date Fair Value, Restricted stock units and awards

$ 34.65

$ 34.58

$ 13.71

[1]	The Company granted its new CEO 3,300,000 options with service and market conditions. These options have a five-year cliff vesting schedule. The fair value of $13.48 for these options was determined by a lattice model with Monte Carlo simulations. The remaining 279,467 service-based options which have a weighted average grant date fair value of $15.49 have a four-year vesting schedule with 25% vest on the first anniversary and 1/48 monthly thereafter.
[2]	The Company granted certain executives 156,029 restricted stock units (“RSUs”) with certain sales target and regulatory milestones. As of June 30, 2017, one performance condition of these RSUs was achieved. As a result, 50% of these RSUs became immediately vested and, accordingly, the Company recorded $2.5 million of stock-based compensation expenses. As of June 30, 2017, the remaining two performance conditions have been deemed as not probable of being achieved. If and when deemed probable that such performance milestones may be achieved within the required time frame, the Company may recognize up to $2.6 million of stock-based compensation related to these grants. The remaining RSUs are service-based awards granted to the members of the board of directors.
[3]	The Company granted its new CEO 335,000 restricted stock awards (“RSAs”) with a fair value of $34.65. These RSAs have a four-year vesting schedule with 25% vest on the first anniversary and 1/48 vest monthly thereafter.

Summary of Stock Awards Granted (Parenthetical) (Detail) - USD ($)

3 Months Ended

6 Months Ended

Jun. 30, 2017

Jun. 30, 2016

Jun. 30, 2017

Jun. 30, 2016

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock-based compensation expenses

$ 10,465,000

$ 6,830,000

$ 16,177,000

$ 13,520,000

Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock options granted

3,579,467

^[1]

7,600

4,456,959

^[1]

1,213,376

Fair value of options granted

$ 13.64

$ 15.61

$ 14.16

$ 11.94

Stock-based compensation expenses

$ 6,763,000

$ 5,772,000

$ 11,801,000

$ 11,470,000

Service-Based Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock options granted

279,467

Fair value of options granted

$ 15.49

Restricted Stock Awards (RSAs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Weighted average fair value of stock units granted

335,000

^[2]

341,500

^[2]

25,775

$ 34.65

$ 34.58

$ 13.71

Restricted Stock Units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Weighted average fair value of stock units granted

20,000

181,029

^[3]

$ 36.26

$ 33.03

Vest Monthly Thereafter [Member] | Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vest Monthly Thereafter [Member] | Restricted Stock Awards (RSAs) [Member]

0.02%

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

CEO [Member] | Stock Options [Member]

0.02%

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock options granted

3,300,000

Cliff vesting schedule

5 years

Fair value of options granted

$ 13.48

Vestng period

4 years

CEO [Member] | Restricted Stock Awards (RSAs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vestng period

4 years

Weighted average fair value of stock units granted

335,000

$ 34.65

CEO [Member] | Vest First Anniversary [Member] | Stock Options [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

CEO [Member] | Vest First Anniversary [Member] | Restricted Stock Awards (RSAs) [Member]

25.00%

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Executives [Member] | Restricted Stock Units [Member]

25.00%

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock-based compensation expenses

156,029

$ 2,500,000

Executives [Member] | Restricted Stock Units [Member] | Performance Grants Vested Immediately [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]