Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Federal
Current	$ 450	$ 313	$ 907	$ 768
Deferred	(41)	(123)	232	(266)
Federal income tax	409	190	1,139	502
State
Current	85	82	157	143
Deferred	(4)	(12)	18	(25)
State income tax	81	70	175	118
Total income tax provision	490	260	1,314	620
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	610	403	1,671	1,025
State income tax, at statutory rates, net of federal tax benefit	53	46	114	77
Tax effect of
Tax credits, net of related expenses	(124)	(114)	(319)	(324)
Tax-exempt income	(57)	(56)	(170)	(161)
Noncontrolling interests	8	5	22	12
Other items		(24)	(4)	(9)
Applicable income taxes	490	260	1,314	620
Income Taxes (Textual) [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%	35.00%
Net deferred tax assets (liabilities)	$ (750)		$ (750)		$ 424