Consolidated Statements of Stockholders' Equity - 9 months ended Sep. 30, 2017 - USD ($) $ in Thousands	Total	Common stock	APIC	Accumulated Deficit
Beginning Balance at Dec. 31, 2016	$ 224,581	$ 9	$ 542,807	$ (318,235)
Balance (in shares) at Dec. 31, 2016	86,159,527	86,159,527
Increase (Decrease) in Stockholders' Equity
Net loss	$ (24,374)			(24,374)
Stock Issued During Period, Value, New Issues	17,398		17,398
Stock Issued During Period, Shares, New Issues		1,150,000
Stock-based compensation	23,654		23,654
Shares issued in connection with employee stock plans, net of shares withheld for employee taxes	69,874	$ 1	69,873
Shares issued in connection with employee stock plans, net of shares withheld for employee taxes (in shares)		12,583,056
Ending Balance at Sep. 30, 2017	$ 311,133	$ 10	$ 653,732	$ (342,609)
Balance (in shares) at Sep. 30, 2017	99,892,583	99,892,583