Stock Based-Compensation (Details 2) (USD $)	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance at January 1, 2012	726,224
Grants	162,220
Forfeitures	(14,700)
Vested and Issued	(243,425)
Balance at September 30, 2012	630,319
Weighted Average Grant Date Fair Value Per Share - Balance at January 1, 2012	$ 42.25	$ 48.16
Weighted Average Grant Date Fair Value Per Share - Grants	$ 53.51
Weighted Average Grant Date Fair Value Per Share - Forfeitures	$ 47.16
Weighted Average Grant Date Fair Value Per Share - Vested and issued	$ 33.71