Share-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based employee compensation expense	$ 93.5	$ 86.3	$ 80.8
Unamortized share-based employee compensation, amortization period	5 years
Unamortized share-based employee compensation	210.1
Option Activity [Roll Forward]
January 1	2,643,680	5,590,880	18,301,409
Granted	60,000	60,000	60,000
Exercised	(1,046,540)	(3,021,200)	(12,673,529)
(Forfeited) reinstated	(5,000)	14,000	(97,000)
December 31	1,652,140	2,643,680	5,590,880
Exercisable December 31	1,526,140	2,505,680	5,333,880
January 1, Weighted Average Exercise Price	$ 26.39	$ 25.72	$ 26.22
Granted, Weighted Average Exercise Price	$ 66.16	$ 70.68	$ 49.65
Exercised, Weighted Average Exercise Price	$ 26.19	$ 26.01	$ 26.47
(Forfeited) reinstated, Weighted Average Exercise Price	$ 23.40	$ 23.40	$ 35.98
December 31, Weighted Average Exercise Price	$ 27.97	$ 26.39	$ 25.72
Exercisable December 31, Weighted Average Exercise Price	$ 24.95	$ 24.67	$ 24.89
Options Outstanding and Exercisable [Abstract]
Options Outstanding, Shares	1,652,140
Options Exercisable, Shares	1,526,140
Black-Scholes Assumptions and Weighted Average Fair Value Per Share for Options Granted [Abstract]
Expected option lives	5 years	5 years	5 years
Risk free interest rate	1.40%	1.40%	0.80%
Expected volatility	22.30%	26.00%	29.50%
Dividend yield	3.00%	2.00%	3.10%
Weighted average fair value per option granted	$ 10.50	$ 14.50	$ 10.42
Exercise Price Range - $23.40 to $29.99
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit	$ 23.40
Range of Exercise Prices, upper range limit	$ 29.99
Options Outstanding, Shares	1,437,140
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 91 days
Options Outstanding, Weighted Average Exercise Price	$ 23.40
Options Exercisable, Shares	1,437,140
Options Exercisable, Weighted Average Exercise Price	$ 23.40
Exercise Price Range - $30.00 to $44.99
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit	$ 30.00
Range of Exercise Prices, upper range limit	$ 44.99
Options Outstanding, Shares	41,000
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 42 days
Options Outstanding, Weighted Average Exercise Price	$ 41.57
Options Exercisable, Shares	41,000
Options Exercisable, Weighted Average Exercise Price	$ 41.57
Exercise Price Range - $45.00 to $59.99
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit	$ 45.00
Range of Exercise Prices, upper range limit	$ 59.99
Options Outstanding, Shares	54,000
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 187 days
Options Outstanding, Weighted Average Exercise Price	$ 49.32
Options Exercisable, Shares	30,000
Options Exercisable, Weighted Average Exercise Price	$ 49.05
Exercise Price Range - $60.00 to $70.68
Options Outstanding and Exercisable [Abstract]
Range of Exercise Prices, lower range limit	$ 60.00
Range of Exercise Prices, upper range limit	$ 70.68
Options Outstanding, Shares	120,000
Options Outstanding, Weighted Average Remaining Contractual Life	9 years 133 days
Options Outstanding, Weighted Average Exercise Price	$ 68.42
Options Exercisable, Shares	18,000
Options Exercisable, Weighted Average Exercise Price	$ 70.68
Stock Options [Member]
Share-based employee compensation, terms of award	The exercise price of stock option awards may not 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	Typically, stock option awards vest 30% per year in the first two years and are fully vested three years from grant date.
Restricted Stock [Member]
Share-based employee compensation, vesting rights	Restricted shares typically 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	6,090,697	7,241,490	6,038,978
Granted	915,922	706,900	2,515,127
Vested	(1,619,444)	(1,490,786)	(981,737)
Forfeited	(346,534)	(366,907)	(330,878)
December 31	5,040,641	6,090,697	7,241,490
Restricted Stock and PRSU Activity, Weighted Average Grant Date Fair Value [Roll Forward]
January 1, Weighted Average Grant Date Fair Value	$ 47.47	$ 45.34
Granted, Weighted Average Grant Date Fair Value	$ 64.92	$ 60.98	$ 49.55
December 31, Weighted Average Grant Date Fair Value	$ 50.98	$ 47.47	$ 45.34
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. The PRSUs granted in 2011 (“2011 PRSUs”) vest over five years and all other PRSUs vest over three years.
Restricted Stock and PRSU Activity [Roll Forward]
January 1	681,555	538,948	413,909
Granted	188,621	183,998	166,426
Vested	(165,562)	(41,391)	(41,387)
Forfeited	(81,755)	0	0
December 31	622,859	681,555	538,948
Restricted Stock and PRSU Activity, Weighted Average Grant Date Fair Value [Roll Forward]
January 1, Weighted Average Grant Date Fair Value	$ 51.19	$ 48.74	$ 48.56
Granted, Weighted Average Grant Date Fair Value	$ 69.89	$ 57.77	$ 49.13
Distributed, Weighted Average Grant Date Fair Value	$ 48.56	$ 48.56	$ 48.56
Forfeited, Weighted Average Grant Date Fair Value	$ 61.76	$ 0.00	$ 0.00
December 31, Weighted Average Grant Date Fair Value	$ 56.16	$ 51.19	$ 48.74
Employee Stock Purchase Plan [Member]
Shares available for grant	9,078,083
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	113,293	175,002	189,307
Proceeds from issuance of shares	$ 8.0	$ 9.9	$ 8.6
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	32,671,988
Stock awards other than options, shares available for grant	9,334,854