Share-Based Compensation (Details 1) (Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
	Dec. 31, 2011
Restricted Stock Units (RSUs) [Member]
Restricted stock units
Weighted number of shares, Nonvested, Beginning Balance	1,625,000
Weighted Average Grant Date Fair Value, Beginning of Period	$ 12.99
Number of Shares, Granted	526,000
Weighted Average Grant Date Fair Value, Nonvested, Granted	$ 18.85
Number of Shares Vested	423,000
Vested, weighted average Grant Date Fair Value	$ 12.80
Number Of Shares Forfeited	(122,000)
Forfeited, Weighted Average Grant Date Fair Value	$ 15.00
Weighted number of shares , Nonvested, Ending Balance	1,606,000
Weighted Average Grant Date Fair Value, Ending of Period	$ 14.81