Stock-Based Compensation Stock-Based Compensation (Details 2) (USD $)	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock Awards Outstanding Shares	501,071	597,648
Weighted Average Grant Date Fair Value Per Share Balance	$ 68.35	$ 48.33
Restricted Stock Awards Activity Shares Granted	118,610
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 64.52
Restricted Stock Award Activity Forfeitures	(2,996)
Restricted Stock Awards Activity Forfeitures Weighted Average Fair Value Per Share	$ 51.33
Restricted Stock Award Activity Vested and Issued	(212,191)
Restricted Stock Award Activity Vested and Isued Weighted Average Fair Value Per Share	$ 50.21