Description of Business and Basis of Presentation (Anti-dilutive Shares) (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Outstanding options to purchase common stock
Schedule of anti-dilutive shares excluded from computation of net loss per share
Anti-dilutive, shares	661	918	636	918
Unvested restricted stock awards
Schedule of anti-dilutive shares excluded from computation of net loss per share
Anti-dilutive, shares	99	286	158	286
Unvested restricted stock unit awards
Schedule of anti-dilutive shares excluded from computation of net loss per share
Anti-dilutive, shares	471	862	1,742	862
Employee stock purchase plan awards
Schedule of anti-dilutive shares excluded from computation of net loss per share
Anti-dilutive, shares	0	24	0	24