Stock-Based Compensation- Stock Option Summary (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding, Number of Shares Underlying Options	301,000	687,000	901,000	1,059,000
Options Outstanding, Weighted Average Remaining Contractual Life (In years)	2 years 2 months 12 days	1 year 10 months 24 days	3 years 3 months 18 days	4 years
Options Outstanding, Weighted Average Exercise Price per Share	$ 43.93	$ 39.68	$ 38.06	$ 36.31
Options Exercisable, Number of Shares Underlying Options	301,000
Options Exercisable, Weighted Average Exercise Price per Share	$ 43.93
Range Two Twenty-seven Dollars Fifty-one Cents To Thirty-five Dollars [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 27.51
Exercise Price Upper Range Limit	$ 35.00
Options Outstanding, Number of Shares Underlying Options	66,000
Options Outstanding, Weighted Average Remaining Contractual Life (In years)	0 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price per Share	$ 31.94
Options Exercisable, Number of Shares Underlying Options	66,000
Options Exercisable, Weighted Average Exercise Price per Share	$ 31.94
Range Three Thirty-five Dollars One Cent To Forty-one Dollars Seventy-two Cents [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 35.01
Exercise Price Upper Range Limit	$ 41.72
Options Outstanding, Number of Shares Underlying Options	27,000
Options Outstanding, Weighted Average Remaining Contractual Life (In years)	0 years 3 months 18 days
Options Outstanding, Weighted Average Exercise Price per Share	$ 38.44
Options Exercisable, Number of Shares Underlying Options	27,000
Options Exercisable, Weighted Average Exercise Price per Share	$ 38.44
Range Four Forty-one Dollars Seventy-three Cents To Forty-eight Dollars Forty-five Cents [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 41.73
Exercise Price Upper Range Limit	$ 48.45
Options Outstanding, Number of Shares Underlying Options	208,000
Options Outstanding, Weighted Average Remaining Contractual Life (In years)	3 years 1 month 6 days
Options Outstanding, Weighted Average Exercise Price per Share	$ 48.45
Options Exercisable, Number of Shares Underlying Options	208,000
Options Exercisable, Weighted Average Exercise Price per Share	$ 48.45