Stock Options and Restricted Stock Stock Options, Stock Option Activity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2012		Dec. 31, 2011
Stock Option Activity [Roll Forward]
Balance, December 31, 2011 (shares)	9,086,586
Options granted, number of shares	626,500	[1]
Exercised, number of shares	(71,442)
Canceled/forfeited, number of shares	(399,652)
Balance, June 30, 2012 (shares)	9,241,992		9,086,586
Balance, December 31, 2011 (usd per share)	$ 10.79
Options granted, weighted average exercise price (usd per share)	$ 25.03	[1]
Exercised, weighted-average exercise price (usd per share)	$ 18.92
Canceled/forfeited, weighted-average exercise price (usd per share)	$ 19.09
Balance, June 30, 2012 (usd per share)	$ 11.33		$ 10.79
Aggregate Intrinsic Value	$ 140,159	[2]	$ 86,590	[2]
Weighted Average Remaining Contractual Terms (in years)	6 years 10 months 24 days		7 years 3 months 18 days
Vested and exercisable as of June 30, 2012, number of shares	5,780,981
Vested and exercisable as of June 30, 2012, weighted average exercise price (usd per share)	$ 8.09
Vested and exercisable as of June 30, 2012, aggregate intrinsic value	106,431	[2]
Vested and exercisable as of June 30, 2012, weighted average remaining contractual term	5 years 10 months 24 days
Vested and exercisable as of June 30, 2012 and expected to vest thereafter, number of shares	8,653,670	[3]
Vested and exercisable as of June 30, 2012 and expected to vest thereafter, weigthed average exercise price (usd per share)	$ 10.85	[3]
Vested and exercisable as of June 30, 2012 and expected to vest thereafter, aggregate intrinsic value	$ 135,450	[2],[3]
Vested and exercisable as of June 30, 2012 and expected to vest thereafter, weighted average remaining contractual term	6 years 9 months 18 days	[3]

[1] Includes 242,500 shares granted to non-employees. The assumptions used to value these grants are similar to those used for grants made to employees with the exception of the expected term.

[2] The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying award and the fair value of $26.50, and $20.14 of our common stock on June 30, 2012, and December 31, 2011.

[3] Stock options expected to vest reflect an estimated forfeiture rate.