Stock-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified			12 Months Ended
	Dec. 31, 2011	May 31, 2010	Dec. 31, 2011 Non-Qualified Stock Options Y	Dec. 31, 2010 Non-Qualified Stock Options Y	Dec. 31, 2009 Non-Qualified Stock Options Y
Stock Based Compensation
2010 increase in number of shares authorized for issuance under Amended and Restated 2007 Long-Term Incentive Plan		9,000,000
Number of shares available for issuance under the 2007 Long-Term Incentive Plan	10,143,863
Maximum vesting period for non-qualified stock options (in years)			P3Y
Expiration of non-qualified stock options from date of grant (in years)			P10Y
Weighted- average assumptions for Black-Scholes option pricing model
Risk-free interest rate (as a percent)			1.69%	1.87%	1.95%
Expected life (in years)			4.0	4.0	4.0
Expected market price volatility factor (as a percent)			27.70%	32.50%	37.80%
Expected dividend yield (as a percent)			3.17%	2.74%	4.83%
Changes in stock option grants, shares
Outstanding, beginning of year			9,070,000	8,146,000	6,058,000
Granted with exercise prices at fair market value			2,244,000	1,468,000	3,511,000
Exercised			(474,000)	(235,000)	(83,000)
Forfeited/expired			(184,000)	(309,000)	(1,340,000)
Outstanding, end of year			10,656,000	9,070,000	8,146,000
Exercisable, end of year (in shares)			6,539,000	5,316,000	4,114,000
Changes in stock option grants, weighted average exercise price
Outstanding, beginning of year (in dollars per share)			$ 43.43	$ 44.36	$ 59.99
Granted with exercise prices at fair market value (in dollars per share)			$ 30.25	$ 35.07	$ 20.14
Exercised (in dollars per share)			$ 23.59	$ 23.53	$ 31.07
Forfeited/expired (in dollars per share)			$ 56.58	$ 43.41	$ 52.41
Outstanding, end of year (in dollars per share)			$ 41.31	$ 43.43	$ 44.36
Exercisable, end of year (in dollars per share)			$ 49.15	$ 52.65	$ 55.81
Weighted-average fair value per share of options granted with exercise prices at fair market value (in dollars per share)			$ 5.20	$ 7.60	$ 4.24
Additional information about stock options
Stock Option Expense Recognized			$ 10.3	$ 9.9	$ 14.2
Cash Received for Exercise Price			11.2	5.5	2.6
Intrinsic Value Realized by Employee			5.9	2.7	0.2
Realized Tax Benefit			2.4	1.1	0.1
Fair Value of Options that Vested			52.4	54.4	11.0
Unrecognized compensation cost related to the unvested portion of outstanding stock option awards (in dollars)			4.1
Compensation cost related to the unvested portion of outstanding stock option awards expected to be recognized in next year (in dollars)			$ 3.1