Consolidated Statements of Stockholders' Equity - 3 months ended Mar. 31, 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	$ (6,795)			(6,795)
Stock-based compensation	6,125		6,125
Shares issued in connection with employee stock plans, net of shares withheld for employee taxes	7,656		7,656
Shares issued in connection with employee stock plans, net of shares withheld for employee taxes (in shares)		2,938,899
Ending Balance at Mar. 31, 2017	$ 231,567	$ 9	$ 556,588	$ (325,030)
Balance (in shares) at Mar. 31, 2017	89,098,426	89,098,426