Equity (Details 4) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			0 Months Ended			0 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	May 10, 2005 Employee Plan	Dec. 31, 2013 Employee Plan	Dec. 31, 1995 1995 Plan	May 10, 2005 Directors Plan	Dec. 31, 2013 Directors Plan	Dec. 31, 2013 Stock options	Dec. 31, 2012 Stock options	Dec. 31, 2011 Stock options	Dec. 31, 2012 Stock options Minimum	Dec. 31, 2012 Stock options Maximum	Dec. 31, 2013 Additional paid-in capital	Dec. 31, 2012 Additional paid-in capital	Dec. 31, 2011 Additional paid-in capital
Share-Based Compensation
Amortization of share based compensation	$ 16.9	$ 25.5	$ 20.5											$ 16.9	$ 25.5	$ 20.5
Tax benefits recognized from share-based compensation arrangements	6.6	9.9	8.0
Excess tax benefit, classified as financing cash inflows	11.4	5.5	1.4
Proceeds from issuance of common stock	$ 30.6	$ 61.9	$ 64.8
Number of additional shares authorized				4,000,000			300,000
Number of shares authorized						30,000,000
Number of shares available					5,800,000			156,015
Vesting period									3 years
Number of years upon which expected stock price volatility is based									3 years
Ranges of assumptions and weighted-average assumptions used for grants made under the option plans and the range of fair values and weighted-average fair value of options granted:
Weighted average risk free interest rate (as a percent)										0.89%	1.25%
Range of risk free interest rates, minimum (as a percent)										0.80%
Range of risk free interest rates, maximum (as a percent)										1.15%
Weighted average expected life of option (in years)										6 years	6 years
Weighted average expected stock volatility (as a percent)										26.63%	30.75%
Range of expected stock volatilities, minimum (as a percent)										25.11%
Range of expected stock volatilities, maximum (as a percent)										30.75%	30.75%
Weighted average expected dividend yield (as a percent)										1.95%	2.21%	1.87%	1.99%
Weighted average stock option fair value (in dollars per share)										$ 11.11	$ 11.38	$ 10.73	$ 12.97