Segment Information (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reconciliation from segment income to net income
Total segment income	$ 715	$ 657	$ 1,497	$ 1,311
Other operating revenue	4,525	4,612	9,038	9,222
Depreciation and amortization	(1,123)	(1,208)	(2,240)	(2,416)
Other unassigned operating expenses	(814)	(835)	(1,632)	(1,706)
Other income (expense), net	(321)	(534)	(598)	(857)
Income tax expense	(125)	(49)	(332)	(180)
NET INCOME	269	74	567	274
Operating segments
Reconciliation from segment income to net income
Total segment income	2,214	2,283	4,525	4,607
Unallocated amount to segment
Reconciliation from segment income to net income
Other operating revenue	249	266	506	532
Depreciation and amortization	(1,123)	(1,208)	(2,240)	(2,416)
Other unassigned operating expenses	(625)	(684)	(1,294)	(1,412)
Other income (expense), net	(321)	(534)	(598)	(857)
Income tax expense	$ (125)	$ (49)	$ (332)	$ (180)