Stock-Based Compensation, Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Stock-Based Compensation [Abstract]
Shares, Outstanding, Beginning Balance (in shares)	4,146,064
Shares, Granted (in shares)	206,174
Shares, Exercised (in shares)	(350,147)
Shares, Forfeited or expired (in shares)	(94,538)
Shares, Outstanding, Ending Balance (in shares)	3,907,553		4,146,064
Shares, Exercisable (in shares)	2,076,701
Shares, Vested and expected to vest (in shares)	3,689,857
Weighted- Average Exercise Price, Outstanding, Beginning Balance (in dollars per share)	$ 16.90
Weighted- Average Exercise Price, Granted (in dollars per share)	17.60
Weighted- Average Exercise Price, Exercised (in dollars per share)	1.12
Weighted- Average Exercise Price, Forfeited or expired (in dollars per share)	28.70
Weighted- Average Exercise Price, Outstanding, Ending Balance (in dollars per share)	18.06		$ 16.90
Weighted- Average Exercise Price, Exercisable (in dollars per share)	11.75
Weighted- Average Exercise Price, Vested and expected to vest (in dollars per share)	$ 17.71
Weighted- Average Remaining Contractual Term, Outstanding	7 years 4 months 24 days		7 years 4 months 24 days
Weighted- Average Remaining Contractual Term, Exercisable	6 years 2 months 12 days
Weighted- Average Remaining Contractual Term, Vested and expected to vest	7 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding, Ending Balance	$ 41,198
Aggregate Intrinsic Value, Exercisable	33,306
Aggregate Intrinsic Value, Vested and expected to vest	$ 40,055
Weighted-average grant-date fair value of options granted (in dollars per share)	$ 12.78
Intrinsic value of options exercised	$ 7,200
Cash received for options exercised	351	$ 425
Fair value of shares vested	6,000
Unrecognized compensation expense related to non-vested stock-options, net of related forfeiture estimates	$ 25,800
Unrecognized compensation expense recognition period	3 years