Employee Benefit Plans (Details 2) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Stock option activity
Beginning balance, Shares			4,540
Granted, Shares	79	32	871	138
Exercised, Shares			(8)
Forfeited, Shares			(160)
Ending balance, Shares	5,243		5,243		4,540
Vested and expected to vest, Shares	4,451		4,451
Exercisable, Shares	4,196		4,196
Beginning balance, Weighted average exercise price			$ 7.29
Granted, Weighted average exercise price			$ 9.69
Exercised, Weighted average exercise price			$ 1.00
Forfeited, Weighted average exercise price			$ 7.86
Ending Balance, Weighted average exercise price	$ 7.68		$ 7.68		$ 7.29
Vested and expected to vest, Weighted average exercise price	$ 7.62		$ 7.62
Exercisable, Weighted average exercise price	$ 7.32		$ 7.32
Stock option outstanding, Remaining contractual term (years)			6 years 8 months 19 days		6 years 7 months 13 days
Vested and expected to vest, Remaining contractual term (years)			6 years 3 months 22 days
Exercisable, Remaining contractual term (years)			6 years 26 days
Stock option outstanding, Aggregate intrinsic value	$ 38,665		$ 38,665		$ 10,888
Vested and expected to vest, Aggregate intrinsic value	29,845		29,845
Exercisable, Aggregate intrinsic value	$ 28,690		$ 28,690