Share-Based Compensation, Stock Equivalent Unit Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Instruments Other than Options Activity [Roll Forward]
Balance at January 1 (in shares)	1,322,000
Granted (in shares)	496,000	588,000	774,000
Dividend equivalents (in shares)	62,000
Balance at December 31 (in shares)	1,025,000	1,322,000
Equity Instruments Other than Options, Weighted Average Grant Date Fair Value [Abstract]
Balance at January 1, weighted average grant date fair value (in dollars per share)	$ 28.63
Granted, weighted average grant date fair value (in dollars per share)	36.09	$ 29.90	$ 27.65
Dividend equivalents, weighted average grant date fair value (in dollars per share)	30.25
Balance at December 31, weighted average grant date fair value (in dollars per share)	$ 32.81	$ 28.63
Stock Equivalent Units [Member]
Equity Instruments Other than Options Activity [Roll Forward]
Balance at January 1 (in shares)	690,000
Granted (in shares)	60,000	62,000	69,000
Units distributed (in shares)	(29,000)
Dividend equivalents (in shares)	25,000
Balance at December 31 (in shares)	746,000	690,000
Equity Instruments Other than Options, Weighted Average Grant Date Fair Value [Abstract]
Balance at January 1, weighted average grant date fair value (in dollars per share)	$ 24.03
Granted, weighted average grant date fair value (in dollars per share)	34.58	$ 30.57	$ 29.52
Units distributed, weighted average grant date fair value (in dollars per share)	20.71
Dividend equivalents, weighted average grant date fair value (in dollars per share)	35.26
Balance at December 31, weighted average grant date fair value (in dollars per share)	$ 25.38	$ 24.03
Equity Instruments Other than Options, Additional Disclosures [Abstract]
Number of shares of common stock into which the share-based compensation can be converted (in shares)	1