Stock Based Compensation (Performance Units Information) (Details) (Performance Units [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Performance Units [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	749,993
Shares, Granted	420,385
Shares, Vested	(270,140)
Shares, Canceled	(98,120)
Shares, Outstanding at December 31, 2013	802,118	749,993
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	$ 32.70
Shares, Granted, Weighted Average Grant Date Fair Value	$ 35.07	$ 31.25	$ 35.33
Shares, Vested, Weighted Average Grant Date Fair Value	$ 34.26
Shares, Cancelled, Weighted Average Grant Date Fair Value	$ 34.10
Shares, Outstanding at December 31, 2012, Weighted Average Grant Date Fair Value	$ 33.25	$ 32.70
Shares, Outstanding at December 31, 2013, Weighted Average Remaining Years Contractual Term	1 year 6 months 6 days
Shares, Outstanding at December 31, 2013, Aggregate Intrinsic Value	$ 25,699,861