Statement of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total
Balance (Scenario, Previously Reported) at Dec. 31, 2017	$ 470	$ 570,670	$ (1,808)	$ (287,286)	$ 282,046
Balance at Dec. 31, 2017	$ 470	570,670	(1,808)	(252,868)	316,464
Balance (in shares) (Scenario, Previously Reported) at Dec. 31, 2017	47,002,488
Balance (in shares) at Dec. 31, 2017	47,002,488
Increase (Decrease) in Stockholders' Equity
Adoption of ASC 606 | ASU 2014-09				34,418	34,418
Balance, revised	$ 470	570,670	(1,808)	(252,868)	316,464
Sale of common stock, net of issuance cost	$ 84	245,420			245,504
Sale of common stock, net of issuance cost (in shares)	8,395,000
Issuance of common stock upon exercise of stock awards	$ 4	2,911			2,915
Issuance of common stock upon exercise of stock awards (in shares)	397,270
Issuance of common stock under the Employee Stock Purchase Plan		504			504
Issuance of common stock under the Employee Stock Purchase Plan (in shares)	26,552
Comprehensive loss			(200)	(55,361)	(55,561)
Stock-based compensation expense		9,353			9,353
Balance at Jun. 30, 2018	$ 558	$ 828,858	$ (2,008)	$ (308,229)	$ 519,179
Balance (in shares) at Jun. 30, 2018	55,821,310