Income Taxes (Details 1) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Feb. 28, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current Income Tax Expense [Abstract]
Current federal income tax expense		$ 1,738	$ 1,335	$ 862
Current state income tax expense		199	153	124
Total current income tax expense		1,937	1,488	986
Deferred Income Tax Expense [Abstract]
Deferred federal income tax expense		659	760	894
Deferred state income tax expense		119	120	70
Total deferred income tax expense		778	880	964
Unrecognized Tax Benefits [Abstract]
Unrecognized federal tax benefits expense		(54)	5	11
Unrecognized state tax benefits expense		(1)	2	11
Unrecognized tax benefits expense / (benefits)		(55)	7	22
Total income tax expense		2,660	2,375	1,972
Deferred tax expense	$ (14)