Changes in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in Other Comprehensive income
Balances as of start of period			$ (1,919)
Pension and other postretirement benefit gains	$ (7)	$ (7)	(36)	$ (48)
Balances as of end of period	(2,374)		(2,374)
Accumulated Other Comprehensive (Loss) Income [Member]
Changes in Other Comprehensive income
Balances as of start of period	(2,154)	(1,371)	(1,919)	(1,426)
Net unrealized gains (losses)	(6)	2	(26)	102
Increase (decrease) due to amounts reclassified into earnings	(1)	(12)	(2)	(66)
Net translation gain (losses) of investments in foreign operations	(604)	(414)	(1,009)	(313)
Net (losses) gains related to hedges of investment in foreign operations	384	246	546	113
Pension and other postretirement benefit gains	7	7	36	48
Net change in accumulated other comprehensive income (loss)	(220)	(171)	(455)	(116)
Balances as of end of period	(2,374)	(1,542)	(2,374)	(1,542)
Net Unrealized Investment Gains (Losses) on Investment Securities [Member]
Changes in Other Comprehensive income
Balances as of start of period	76	105	96	63
Net unrealized gains (losses)	(6)	2	(26)	102
Increase (decrease) due to amounts reclassified into earnings	(1)	(13)	(1)	(71)
Net translation gain (losses) of investments in foreign operations	0	0	0	0
Net (losses) gains related to hedges of investment in foreign operations	0	0	0	0
Pension and other postretirement benefit gains	0	0	0	0
Net change in accumulated other comprehensive income (loss)	(7)	(11)	(27)	31
Balances as of end of period	69	94	69	94
Foreign Currency Translation Adjustments [Member]
Changes in Other Comprehensive income
Balances as of start of period	(1,743)	(1,118)	(1,499)	(1,090)
Net unrealized gains (losses)	0	0	0	0
Increase (decrease) due to amounts reclassified into earnings	0	1	(1)	5
Net translation gain (losses) of investments in foreign operations	(604)	(414)	(1,009)	(313)
Net (losses) gains related to hedges of investment in foreign operations	384	246	546	113
Pension and other postretirement benefit gains	0	0	0	0
Net change in accumulated other comprehensive income (loss)	(220)	(167)	(464)	(195)
Balances as of end of period	(1,963)	(1,285)	(1,963)	(1,285)
Net Unrealized Pension and Other Postretirement Benefit Losses [Member]
Changes in Other Comprehensive income
Balances as of start of period	(487)	(358)	(516)	(399)
Net unrealized gains (losses)	0	0	0	0
Increase (decrease) due to amounts reclassified into earnings	0	0	0	0
Net translation gain (losses) of investments in foreign operations	0	0	0	0
Net (losses) gains related to hedges of investment in foreign operations	0	0	0	0
Pension and other postretirement benefit gains	7	7	36	48
Net change in accumulated other comprehensive income (loss)	7	7	36	48
Balances as of end of period	$ (480)	$ (351)	$ (480)	$ (351)