Stockholders' Equity - Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			$ (507)	$ (95)
Other comprehensive income (loss) before reclassifications				574
Amounts reclassified out of AOCI				10
Other comprehensive income (loss)	$ (5)	$ 301	(504)	584
AOCI net of tax, ending balance	(1,011)	489	(1,011)	489
Accumulated Other Comprehensive Income (Loss)
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			(507)
Other comprehensive income (loss) before reclassifications			(517)
Amounts reclassified out of AOCI			13
Other comprehensive income (loss)			(504)
AOCI net of tax, ending balance	(1,011)		(1,011)
Net Unrealized Gains (Losses) on Cash Flow Hedges
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			276	161
Other comprehensive income (loss) before reclassifications			19	(62)
Amounts reclassified out of AOCI			1	1
Other comprehensive income (loss)			20	(61)
AOCI net of tax, ending balance	296	100	296	100
Net Unrealized Gains (Losses) on Available-for-Sale Securities
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			192	(221)
Other comprehensive income (loss) before reclassifications			(134)	551
Amounts reclassified out of AOCI			(2)	(9)
Other comprehensive income (loss)			(136)	542
AOCI net of tax, ending balance	56	321	56	321
Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			(14)	(14)
Other comprehensive income (loss) before reclassifications			0	0
Amounts reclassified out of AOCI			0	0
Other comprehensive income (loss)			0	0
AOCI net of tax, ending balance	(14)	(14)	(14)	(14)
Other-Than-Temporary Impairment on Held-to-Maturity Securities
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			(29)	(47)
Other comprehensive income (loss) before reclassifications			8	11
Amounts reclassified out of AOCI			(1)	1
Other comprehensive income (loss)			7	12
AOCI net of tax, ending balance	(22)	(35)	(22)	(35)
Net Unrealized Losses on Retirement Plans
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			(272)	(203)
Other comprehensive income (loss) before reclassifications			0	1
Amounts reclassified out of AOCI			15	17
Other comprehensive income (loss)			15	18
AOCI net of tax, ending balance	(257)	(185)	(257)	(185)
Foreign Currency Translation
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			(660)	229
Other comprehensive income (loss) before reclassifications			(410)	73
Amounts reclassified out of AOCI			0	0
Other comprehensive income (loss)			(410)	73
AOCI net of tax, ending balance	$ (1,070)	$ 302	$ (1,070)	$ 302