Stock Based-Compensation (Details 5) (USD $)	12 Months Ended
	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at January 1, 2011	757,414
Grants	381,840
Forfeitures	(66,675)
Vested and Issued	(346,355)
Balance at December 31, 2011	726,224
Weighted Average Grant Date Fair Value Per Share - Balance at January 1, 2011	$ 37.32
Weighted Average Grant Date Fair Value Per Share - Grants	$ 47.98
Weighted Average Grant Date Fair Value Per Share - Foreitures	$ 40.92
Weighted Average Grant Date Fair Value Per Share - Vested and issued	$ 38.25
Weighted Average Grant Date Fair Value Per Share - Balance at December 31, 2011	$ 42.25