Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance (shares) at Dec. 31, 2013		25,811
Beginning Balance at Dec. 31, 2013	$ 96,414	$ 26	$ 354,465	$ (730)	$ (257,347)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon purchase of DVS (in shares)		1,945
Issuance of common stock upon purchase of DVS	76,807	$ 2	76,805
Vested DVS stock options converted to equivalent vested options	4,039		4,039
Issuance of common stock upon exercise of stock options for cash and release of restricted stock units (shares)		585
Issuance of common stock upon exercise of stock options for cash and release of restricted stock units	5,113		5,113
Gain from escrow settlement	0
Stock-based compensation expense	20,940		20,940
Net loss	(52,830)				(52,830)
Other comprehensive income (loss)	(64)			(64)
Ending Balance (shares) at Dec. 31, 2014		28,341
Ending Balance at Dec. 31, 2014	150,419	$ 28	461,362	(794)	(310,177)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options for cash and release of restricted stock units (shares)		673
Issuance of common stock upon exercise of stock options for cash and release of restricted stock units	5,303	$ 1	5,302
Gain on escrow settlement (shares)		(170)
Gain from escrow settlement	(3,986)		(3,986)
Stock-based compensation expense	16,830		16,830
Net loss	(53,315)				(53,315)
Other comprehensive income (loss)	(350)			(350)
Ending Balance (shares) at Dec. 31, 2015		28,844
Ending Balance at Dec. 31, 2015	$ 114,901	$ 29	479,508	(1,144)	(363,492)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options for cash and release of restricted stock units (shares)	57	364
Issuance of common stock upon exercise of stock options for cash and release of restricted stock units	$ 75		75
Gain from escrow settlement	0
Stock-based compensation expense	13,858		13,858
Net loss	(75,985)				(75,985)
Other comprehensive income (loss)	384			384
Ending Balance (shares) at Dec. 31, 2016		29,208
Ending Balance at Dec. 31, 2016	$ 53,233	$ 29	$ 493,441	$ (760)	$ (439,477)