Stockholders' Equity (Details 5) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Options
Outstanding Options, Beginning of period	11,371,891	10,771,755
Options granted	2,281,786	1,661,862
Options exercised	(1,262,663)	(65,000)
Options cancelled	(73,229)	(135,398)
Options expired	(77,318)	(861,328)
Outstanding Options, End of period	12,240,467	11,371,891
Exercisable at the end of period	7,038,372	6,281,300
Weighted-Average Exercise Price
Outstanding Exercise Price (in dollars per share)	$ 15.12	$ 15.39
Options granted (in dollars per share)	15.70	15.04
Options exercised (in dollars per share)	13.06	10.79
Options cancelled (in dollars per share)	13.27	15.74
Options expired (in dollars per share)	22.26	18.48
Outstanding Exercise Price (in dollars per share)	15.41	15.12
Exercisable at the end of period	$ 16.31	$ 16.95
Additional Disclosures
Outstanding Contractual Term (in Years)	4 years 4 months 6 days	4 years 7 months 13 days
Outstanding Intrinsic Value	$ 14,438	$ 1,815
Exercisable at the end of period (in Years)	3 years 4 months 28 days	3 years 6 months 15 days
Exercisable aggregate intrinsic value	$ 9,940	$ 871