Stock Based Compensation (Restricted Stock Units Activity) (Details) (Restricted Stock Units (RSUs) [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Shares, Outstanding at January 1, 2013	834,527
Shares, Granted	325,035
Shares, Vested	(109,691)
Shares, Canceled	(2,302)
Shares, Outstanding at December 31, 2013	1,047,569	834,527
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Shares, Outstanding at January 1, 2012, Weighted Average Grant Date Fair Value	$ 31.12
Shares, Granted, Weighted Average Grant Date Fair Value	$ 31.41	$ 30.95	$ 32.03
Shares, Vested, Weighted Average Grant Date Fair Value	$ 30.25
Shares, Canceled, Weighted Average Grant Date Fair Value	$ 31.49
Shares, Outstanding at December 31, 2012, Weighted Average Grant Date Fair Value	$ 31.30	$ 31.12
Shares, Outstanding at December 31, 2013, Weighted Average Remaining Years Contractual Term	1 year 1 month 5 days
Shares, Outstanding at December 31, 2013, Aggregate Intrinsic Value	$ 33,564,117