Share-Based Compensation Plans (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) shares $ / shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares
Share-based employee compensation expense | $	$ 99.4	$ 93.5	$ 86.3
Unamortized share-based employee compensation, amortization period	5 years
Unamortized share-based employee compensation | $	$ 185.7
Option Activity [Roll Forward]
January 1	1,652,140	2,643,680	5,590,880
Granted	0	60,000	60,000
Exercised	(511,593)	(1,046,540)	(3,021,200)
(Forfeited) reinstated	0	(5,000)
Reinstated, net of forfeited			14,000
December 31	1,140,547	1,652,140	2,643,680
Exercisable December 31	1,074,547	1,526,140	2,505,680
January 1, Weighted Average Exercise Price | $ / shares	$ 27.97	$ 26.39	$ 25.72
Granted, Weighted Average Exercise Price | $ / shares		66.16	70.68
Exercised, Weighted Average Exercise Price | $ / shares	25.98	26.19	26.01
Forfeited, Weighted Average Exercise Price | $ / shares		23.40
Reinstated, net of forfeited, Weighted Average Exercise Price | $ / shares			23.40
December 31, Weighted Average Exercise Price | $ / shares	28.86	27.97	26.39
Exercisable December 31, Weighted Average Exercise Price | $ / shares	$ 26.47	$ 24.95	$ 24.67
Options Outstanding and Exercisable [Abstract]
Options Outstanding, Shares	1,140,547
Options Exercisable, Shares	1,074,547
Black-Scholes Assumptions and Weighted Average Fair Value Per Share for Options Granted [Abstract]
Expected option lives		5 years	5 years
Risk free interest rate		1.40%	1.40%
Expected volatility		22.30%	26.00%
Dividend yield		3.00%	2.00%
Weighted average fair value per option granted | $ / shares		$ 10.50	$ 14.50
Exercise Price Range - $23.40 to $29.99
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit | $ / shares	$ 23.40
Range of Exercise Prices, upper range limit | $ / shares	$ 29.99
Options Outstanding, Shares	978,547
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 2 months
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 23.40
Options Exercisable, Shares	978,547
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 23.40
Exercise Price Range - $30.00 to $44.99
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit | $ / shares	30.00
Range of Exercise Prices, upper range limit | $ / shares	$ 44.99
Options Outstanding, Shares	21,000
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 11 months
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 43.49
Options Exercisable, Shares	21,000
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 43.49
Exercise Price Range - $45.00 to $59.99
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit | $ / shares	45.00
Range of Exercise Prices, upper range limit | $ / shares	$ 59.99
Options Outstanding, Shares	30,000
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 10 months
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 49.65
Options Exercisable, Shares	30,000
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 49.65
Exercise Price Range - $60.00 to $70.68
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit | $ / shares	60.00
Range of Exercise Prices, upper range limit | $ / shares	$ 70.68
Options Outstanding, Shares	111,000
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 4 months
Options Outstanding, Weighted Average Exercise Price | $ / shares	$ 68.60
Options Exercisable, Shares	45,000
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 69.78
Stock Options [Member]
Share-based employee compensation, terms of award	The exercise price of stock option awards cannot be less than 100% of the market price of our common stock on the grant date and the option term cannot exceed ten years from the grant date.
Share-based employee compensation, vesting rights	Generally, stock option awards vest 30% per year in the first two years and are fully vested three years from the grant date.
Restricted Stock [Member]
Share-based employee compensation, vesting rights	Generally, restricted shares vest 20% per year and are fully vested five years from the grant date provided the employee remains employed by us.
Restricted Stock and PRSU Activity [Roll Forward]
January 1	5,040,641	6,090,697	7,241,490
Granted	1,208,964	915,922	706,900
Vested / Distributed	(1,631,343)	(1,619,444)	(1,490,786)
Forfeited	(269,157)	(346,534)	(366,907)
December 31	4,349,105	5,040,641	6,090,697
Restricted Stock and PRSU Activity, Weighted Average Grant Date Fair Value [Roll Forward]
January 1, Weighted Average Grant Date Fair Value | $ / shares	$ 50.98	$ 47.47
Granted, Weighted Average Grant Date Fair Value | $ / shares	64.49	64.92	$ 60.98
December 31, Weighted Average Grant Date Fair Value | $ / shares	$ 55.08	$ 50.98	$ 47.47
Performance Restricted Stock Units (PRSUs) [Member]
Share-based employee compensation, vesting rights	Each PRSU represents the right to receive one share of common stock on vesting. The ultimate number of PRSUs received by the employee depends on the Company's average return on equity over a three year period compared to the average return on equity of a peer group of four principal competitors over the same period. Generally, the PRSUs vest three years from grant date.
Restricted Stock and PRSU Activity [Roll Forward]
January 1	622,859	681,555	538,948
Granted	161,625	188,621	183,998
Vested / Distributed	(239,387)	(165,562)	(41,391)
Forfeited	(10,641)	(81,755)	0
December 31	534,456	622,859	681,555
Restricted Stock and PRSU Activity, Weighted Average Grant Date Fair Value [Roll Forward]
January 1, Weighted Average Grant Date Fair Value | $ / shares	$ 56.16	$ 51.19	$ 48.74
Granted, Weighted Average Grant Date Fair Value | $ / shares	77.68	69.89	57.77
Distributed, Weighted Average Grant Date Fair Value | $ / shares	48.94	48.56	48.56
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	48.87	61.76	0.00
December 31, Weighted Average Grant Date Fair Value | $ / shares	$ 66.05	$ 56.16	$ 51.19
Employee Stock Purchase Plan [Member]
Shares available for grant	8,966,234
Employee Stock Purchase Plan (ESPP) [Abstract]
Discount from market price	95.00%
Maximum percentage of eligible compensation allowable for purchase	10.00%
Shares issued in period	111,849	113,293	175,002
Proceeds from issuance of shares | $	$ 7.8	$ 8.0	$ 9.9
2013 Incentive Award Plan [Member]
Maximum of shares available for issuance	33,000,000
Stock awards other than options, conversion ratio	3.5
Shares available for grant	31,635,829
Stock awards other than options, shares available for grant	9,038,808