Share-Based Compensation (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2013
Restricted Stock Awards [Member]
Summary of restricted stock award and restricted stock units activity
Non-vested, Number of shares, Beginning balance	965,710
Number of shares, Granted	9,775
Number of shares, Vested	(147,221)
Number of shares, Cancelled or expired	(31,212)
Non-vested, Number of shares, Ending balance	797,052
Non-vested, Weighted average Grant Date Fair Value, Beginning balance	$ 4.68
Weighted average Grant Date Fair Value, Granted	$ 10.99
Weighted average Grant Date Fair Value, Vested	$ 4.52
Weighted average Grant Date Fair Value, Cancelled or expired	$ 5.87
Non-vested, Weighted average Grant Date Fair Value, Ending balance	$ 4.75
Restricted Stock Units [Member]
Summary of restricted stock award and restricted stock units activity
Non-vested, Number of shares, Beginning balance
Number of shares, Granted	349,867
Number of shares, Vested	0
Number of shares, Cancelled or expired
Non-vested, Number of shares, Ending balance
Non-vested, Weighted average Grant Date Fair Value, Beginning balance
Weighted average Grant Date Fair Value, Granted	$ 10.89
Weighted average Grant Date Fair Value, Vested
Weighted average Grant Date Fair Value, Cancelled or expired
Non-vested, Weighted average Grant Date Fair Value, Ending balance