Equity Incentive Plans and Stock-Based Compensation (Details 2) - Employee Stock Option [Member] - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Number of Shares
Outstanding, at the beginning of the period (in shares)	8,995,017
Options granted (in shares)	440,000	362,335
Options exercised (in shares)	(749,058)
Options forfeited (in shares)	(773,912)
Outstanding, at the end of the period (in shares)	7,912,047
Vested or expected to vest at the end of the period (in shares)	7,679,174
Options exercisable at the end of the period (in shares)	4,989,516
Weighted Average Exercise Price
Outstanding at the beginning of the year (in dollars per shares)	$ 10.01
Options granted (in dollars per share)	12.31
Options exercised (in dollars per share)	7.01
Options forfeited (in dollars per share)	21.81
Outstanding at the end of the period (in dollars per shares)	9.27
Vested or expected to vest at the end of the period (in dollars per share)	9.30
Options exercisable at the end of the period (in dollars per share)	$ 10.05
Weighted Average Remaining Contractual Term
Outstanding	5 years 8 months 1 day
Vested or expected to vest	5 years 7 months 10 days
Options exercisable	4 years 8 months 19 days
Aggregate Intrinsic Value
Outstanding	$ 31,293
Vested or expected to vest	30,418
Options exercisable	$ 18,970
Stock Options with Market Condition [Member]
Number of Shares
Outstanding, at the beginning of the period (in shares)	1,315,000
Outstanding, at the end of the period (in shares)	1,225,000