CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - 3 months ended Mar. 31, 2016 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Balances (in shares) at Dec. 31, 2015		36,848
Balances at Dec. 31, 2015	$ 218,392	$ 37	$ 526,696	$ (308,289)	$ (52)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (shares)		254
Exercise of stock options	3,041	$ 0	3,041
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period		1
Vested restricted stock units	0	$ 0
Stock-based compensation	8,490		8,490
Net unrealized gain on investments	101				101
Net loss	(3,854)			(3,854)
Balances (in shares) at Mar. 31, 2016		37,103
Balances at Mar. 31, 2016	$ 226,170	$ 37	$ 538,227	$ (312,143)	$ 49