Stock-Based Compensation (Restricted Stock Units Activity) (Details) (Restricted Stock Units (RSUs) [Member], USD $)	3 Months Ended
	Mar. 31, 2013
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
RSUs outstanding, Beginning Balance, Unvested	727,145
RSUs outstanding, Beginning Balance, Vested but Deferred	18,782
RSUs outstanding, Beginning Balance, Total	745,927
RSUs outstanding, Beginning Balance, Weighted Average Grant Date Valueper RSU	53.37
Granted, Unvested	0
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested But Deferred Grants In Period	0
Granted, Total	0
Granted, Weighted Average Grant Date Valueper RSU	$ 0.00
Dividend equivalents, Unvested	0
Dividend equivalents, Vestedd but Deferred	0
Dividend equivalents, Total	0
Dividend equivalents, Weighted Average Grant Date Valueper RSU	$ 0.00
Vested, Unvested	(2,586)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested But Deferred Vested In Period	0
Vested, Total	(2,586)
Vested, Weighted Average Grant Date Valueper RSU	$ 35.83
Vested but deferred, Unvested	0
Vested but deferred, Vested but Deferred	0
Vested but deferred, Total	0
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested but Deferred Weighted Average Grant Date Fair Value	$ 0.00
Share Based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Options Nonvested Issued in Period	0
Issued, Vested but Deferred	0
Issued, Total	0
Issued, Weighted Average Grant Date Valueper RSU	$ 0.00
Forfeited, Unvested	(9,500)
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested But Deferred Forfeited In Period	0
Forfeited, Total	(9,500)
Forfeited, Weighted Average Grant Date Valueper RSU	$ 53.25
RSUs outstanding, Ending Balance, Unvested	715,059
RSUs outstanding, Ending Balance, Vested but Deferred	18,782
RSUs outstanding, Ending Balance, Total	733,841
RSUs outstanding, Ending Balance, Weighted Average Grant Date Valueper RSU	53.87