Reconciliation of Ongoing Earnings (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Reconciliation Ongoing Earnings To Net Income Attributable To Controlling Interests [Abstract]
Ongoing Earnings	$ 143	$ 202
Tax levelization	(7)	(2)
CVO mark-to-market, net of tax	8	0
Merger and integration costs, net of tax (Note 2)	(5)	(14)
Change in tax treatment of the Medicare Part D subsidy	0	0
Continuing income attributable to noncontrolling interests, net of tax	2	1
Income from continuing operations	141	187
Discontinued operations, net of tax	11	(2)
Net income attributable to noncontrolling interests, net of tax	(2)	(1)
Net income attributable to controlling interests	150	184
Tax information [Details]
Merger and integration costs, tax benefit (expense)	$ 2