Summary of Significant Accounting Policies (Details 1) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2011
Unrecognized stock-based compensation
Unrecognized expense	$ 44,002
Restricted stock awards [Member]
Unrecognized stock-based compensation
Unrecognized expense	2,813
Weighted average remaining expense life (Years)	1.5
Performance stock awards [Member]
Unrecognized stock-based compensation
Unrecognized expense	6,567
Weighted average remaining expense life (Years)	2.6
Employee Stock [Member]
Unrecognized stock-based compensation
Unrecognized expense	75
Weighted average remaining expense life (Years)	0.2
Employee Stock Option [Member]
Unrecognized stock-based compensation
Unrecognized expense	33,759
Weighted average remaining expense life (Years)	2.8
Deferred Issuance Restricted Stock [Member]
Unrecognized stock-based compensation
Unrecognized expense	$ 788
Weighted average remaining expense life (Years)	1.5