Accumulated Other Comprehensive Loss (Details 2) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Change in accumulated other comprehensive loss balances:
Beginning Balance	$ (666)	$ (441)	$ (729)	$ (624)
Other comprehensive income (loss) before reclassifications	158	(36)	244	166
Amounts reclassified from AOCI	(17)	(22)	(40)	(41)
Ending Balance	(525)	(499)	(525)	(499)
Net Unrealized Gains (Losses) on Cash Flow Hedges
Change in accumulated other comprehensive loss balances:
Beginning Balance	43	32	21	16
Other comprehensive income (loss) before reclassifications	113	(19)	180	28
Amounts reclassified from AOCI	(29)	(21)	(74)	(52)
Ending Balance	127	(8)	127	(8)
Net Unrealized Gains (Losses) on Securities
Change in accumulated other comprehensive loss balances:
Beginning Balance	(126)	(173)	(145)	(328)
Other comprehensive income (loss) before reclassifications	51	(14)	75	143
Amounts reclassified from AOCI	(4)	(8)	(9)	(10)
Ending Balance	(79)	(195)	(79)	(195)
Foreign Currency Translation Adjustment
Change in accumulated other comprehensive loss balances:
Beginning Balance	(15)	(3)	(10)	(3)
Other comprehensive income (loss) before reclassifications	(6)	(3)	(11)	(3)
Amounts reclassified from AOCI	0	0	0	0
Ending Balance	(21)	(6)	(21)	(6)
Pension and Other Benefits Adjustment
Change in accumulated other comprehensive loss balances:
Beginning Balance	(568)	(297)	(595)	(309)
Other comprehensive income (loss) before reclassifications	0	0	0	(2)
Amounts reclassified from AOCI	16	7	43	21
Ending Balance	$ (552)	$ (290)	$ (552)	$ (290)