Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Federal
Current	$ 404	$ 406
Deferred	68	(44)
Federal income tax	472	362
State
Current	50	10
Deferred	5	(6)
State income tax	55	4
Total income tax provision	527	366
Reconciliation of expected income tax expense at the federal statutory rate of 35 percent to the Company's applicable income tax expense
Tax at statutory rate	641	488
State income tax, at statutory rates, net of federal tax benefit	36	3
Tax effect of
Tax credits, net of related expenses	(89)	(87)
Tax-exempt income	(55)	(56)
Noncontrolling interests	11	6
Other items	(17)	12
Applicable income taxes	$ 527	$ 366