Shareholders' Equity and Stock-Based Compensation (Details 4) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended	12 Months Ended
	Jan. 03, 2012 Y	Mar. 31, 2011 Y	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stock-based Compensation
Vesting period			3 years
Maximum period over which the fair value of restricted stock and restricted stock units are amortized (in years)			three years
Compensation expense			$ 39.4	$ 39.2	$ 29.9
Related tax benefit			15.3	14.7	11.1
Assumptions in determining the fair value of awards granted
Annual expected stock price volatility (as a percent)	44.30%	61.00%
Annual expected dividend yield (as a percent)	1.60%	1.27%
Risk free interest rate (as a percent)	0.44%	1.03%
Correlation between total shareholder return for SPX and S&P 500 Composite Index	0.7365	0.7559
Historical period upon which annual expected stock price volatility is based (in years)			three-year
Minimum daily treasury yield curve period upon which average risk-free interest rate is based (in years)			one-year
Maximum daily treasury yield curve period upon which average risk-free interest rate is based (in years)			three-year
2002 Stock Compensation Plan
Stock-based Compensation
Shares available for grant			3,468,000
Reduction of shares available for grant			2
Stock Options granted to key employees
Stock-based Compensation
Classification of excess tax benefits from stock-based compensation as financing cash flows			$ 3.8	$ 6.6	$ 4.2
S&P 500 Composite Index
Stock-based Compensation
Portion of the grant that will vest if the Company outperforms the S&P composite index for the prior year			one-third
Assumptions in determining the fair value of awards granted
Annual expected stock price volatility (as a percent)	23.10%	30.30%
Risk free interest rate (as a percent)	0.44%	1.03%
2006 Non-Employee Directors' Stock Incentive Plan ("Directors' Plan")
Stock-based Compensation
Maximum common stock authorized for grant (in shares)			13,000