Accumulated Other Comprehensive Loss (Details 2) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Change in accumulated other comprehensive loss balances:
Beginning Balance	$ (752)	$ (729)
Other comprehensive income (loss) before reclassifications	263	140
Amounts reclassified from AOCI	24	(8)
Ending Balance	(513)	(597)
Net Unrealized Gains (Losses) on Cash Flow Hedges
Change in accumulated other comprehensive loss balances:
Beginning Balance	36	21
Other comprehensive income (loss) before reclassifications	161	72
Amounts reclassified from AOCI	(26)	(20)
Ending Balance	171	73
Net Unrealized Gains (Losses) on Securities
Change in accumulated other comprehensive loss balances:
Beginning Balance	(151)	(145)
Other comprehensive income (loss) before reclassifications	99	75
Amounts reclassified from AOCI	(8)	(2)
Ending Balance	(60)	(72)
Foreign Currency Translation Adjustment
Change in accumulated other comprehensive loss balances:
Beginning Balance	(25)	(10)
Other comprehensive income (loss) before reclassifications	4	(7)
Amounts reclassified from AOCI	0	0
Ending Balance	(21)	(17)
Pension and Other Benefits Adjustment
Change in accumulated other comprehensive loss balances:
Beginning Balance	(612)	(595)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from AOCI	10	14
Ending Balance	(602)	(581)
Accumulated Other [Member]
Change in accumulated other comprehensive loss balances:
Beginning Balance	0	0
Other comprehensive income (loss) before reclassifications	(1)	0
Amounts reclassified from AOCI	0	0
Ending Balance	$ (1)	$ 0