Stockholders' Equity - Accumulated Other Comprehensive Income by Component (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			$ (507)
Other comprehensive income (loss)	$ (90)	$ (596)	(594)	$ (12)
AOCI net of tax, ending balance	(1,101)		(1,101)
Accumulated Other Comprehensive Income (Loss)
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance			(507)	(95)
Other comprehensive income (loss) before reclassifications			(611)	(25)
Amounts reclassified out of AOCI			17	13
Other comprehensive income (loss)			(594)	(12)
AOCI net of tax, ending balance	(1,101)	(107)	(1,101)	(107)
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			44	54
Amounts reclassified out of AOCI			2	2
Other comprehensive income (loss)			46	56
AOCI net of tax, ending balance	322	217	322	217
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			(112)	425
Amounts reclassified out of AOCI			(3)	(9)
Other comprehensive income (loss)			(115)	416
AOCI net of tax, ending balance	77	195	77	195
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			12	15
Amounts reclassified out of AOCI			(1)	1
Other comprehensive income (loss)			11	16
AOCI net of tax, ending balance	(18)	(31)	(18)	(31)
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			19	19
Other comprehensive income (loss)			19	18
AOCI net of tax, ending balance	(253)	(185)	(253)	(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			(555)	(518)
Amounts reclassified out of AOCI			0	0
Other comprehensive income (loss)			(555)	(518)
AOCI net of tax, ending balance	$ (1,215)	$ (289)	$ (1,215)	$ (289)