Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Product, net	$ 73,529	$ 35,011	$ 138,133	$ 51,353
Total revenues	73,529	35,011	138,133	51,353
Costs and expenses:
Cost of sales (excluding amortization of in-licensed rights)	6,735	506	12,317	729
Research and development	122,848	58,908	169,052	88,027
Selling, general and administrative	47,156	36,069	90,497	62,285
EXONDYS 51 litigation and license charges		2,839		2,839
Amortization of in-licensed rights	217	28	433	57
Total costs and expenses	176,956	98,350	272,299	153,937
Operating loss	(103,427)	(63,339)	(134,166)	(102,584)
Other (loss) income:
Gain from sale of Priority Review Voucher				125,000
Interest (expense) income and other, net	(5,218)	184	(9,703)	519
Other (loss) income	(5,218)	184	(9,703)	125,519
(Loss) income before income tax expense (benefit)	(108,645)	(63,155)	(143,869)	22,935
Income tax expense (benefit)	622	(109)	761	1,891
Net (loss) income	(109,267)	(63,046)	(144,630)	21,044
Other comprehensive (loss) income:
Unrealized gain on cash equivalents and short-term investments	282	17	18	82
Total other comprehensive income	282	17	18	82
Comprehensive (loss) income	$ (108,985)	$ (63,029)	$ (144,612)	$ 21,126
Net (loss) income per share
Basic (loss) earnings per share	$ (1.67)	$ (1.15)	$ (2.22)	$ 0.38
Diluted (loss) earnings per share	$ (1.67)	$ (1.15)	$ (2.22)	$ 0.37
Weighted average number of shares of common stock used in computing:
Basic (loss) earnings per share	65,484	54,976	65,060	54,913
Diluted (loss) earnings per share	65,484	54,976	65,060	56,176