Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Income Taxes
Effective tax rate on income from continuing operations (as a percent)	23.80%	33.20%	30.30%	28.40%
Decrease to net income resulting from out-of-period correction for tax-related item			$ 32,000,000
Maximum period for recognizing capital losses			5 years
Valuation allowance	5,000,000		5,000,000		5,000,000
Capital loss carryforwards	12,000,000		12,000,000
State net operating losses	39,000,000		39,000,000
Gross unrecognized tax benefit (expense)	103,000,000		103,000,000		184,000,000
Unrecognized tax benefits (net of federal tax benefits) that would impact the effective tax rate	34,000,000		34,000,000		38,000,000
Interest and penalties recognized	0		4,000,000	65,000,000
Estimated decrease in amount of unrecognized tax benefits in next 12 months	78,000,000		78,000,000
Accrued interest and penalties	$ 33,000,000		$ 33,000,000		$ 37,000,000