Statement of Stockholders’ Equity - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2015	$ 405	$ 424,128	$ (516)	$ (261,585)	$ 162,432
Balance (in shares) at Dec. 31, 2015	40,551,039
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise and vesting of stock awards	$ 4	443			447
Issuance of common stock upon exercise and vesting of stock awards (in shares)	374,275
Issuance of common stock under the employee stock purchase plan		226			226
Issuance of common stock under the employee stock purchase plan (in shares)	18,766
Comprehensive income			732	40,767	41,499
Stock-based compensation expense		3,993			3,993
Balance at Jun. 30, 2016	$ 409	$ 428,790	$ 216	$ (220,818)	$ 208,597
Balance (in shares) at Jun. 30, 2016	40,944,080