Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	APIC	Accumulated Deficit
Increase (Decrease) in Stockholders' Equity
Cumulative-effect of accounting change adopted as of January 1, 2018	$ 5,923			$ 5,923
Beginning Balance at Dec. 31, 2017	$ 313,118	$ 10	$ 664,192	(351,084)
Balance (in shares) at Dec. 31, 2017	100,428,656	100,428,656
Increase (Decrease) in Stockholders' Equity
Net loss	$ (15,677)			(15,677)
Stock-based compensation	18,876		18,876
Shares issued in connection with employee stock plans, net of shares withheld for employee taxes	1,739	$ 0	1,739
Shares issued in connection with employee stock plans, net of shares withheld for employee taxes (in shares)		1,177,744
Ending Balance at Jun. 30, 2018	$ 323,979	$ 10	$ 684,807	$ (360,838)
Balance (in shares) at Jun. 30, 2018	101,606,400	101,606,400