Changes in Accumulated Other Comprehensive (Loss) Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in Other Comprehensive income
Balances as of start of period			$ (927)
Pension and other postretirement benefit losses	6	14	60	34
Balances as of end of period	(1,339)		(1,339)
Accumulated Other Comprehensive (Loss) Income [Member]
Changes in Other Comprehensive income
Balances as of start of period	(1,308)	(951)	(927)	(876)
Net unrealized gains / (losses)	(25)	43	(141)	108
Reclassification for realized (gains) / losses into earnings	(23)	(22)	(69)	(55)
Net translation of investments in foreign operations	134	401	(422)	248
Net losses related to hedges of investment in foreign operations	(123)	(320)	160	(294)
Pension and other postretirement benefit losses	6	14	60	34
Net change in accumulated other comprehensive (loss) income	(31)	116	(412)	41
Balances as of end of period	(1,339)	(835)	(1,339)	(835)
Net Unrealized Investment Gains (Losses) on Investment Securities [Member]
Changes in Other Comprehensive income
Balances as of start of period	153	319	315	288
Net unrealized gains / (losses)	(25)	43	(141)	108
Reclassification for realized (gains) / losses into earnings	(23)	(22)	(69)	(56)
Net change in accumulated other comprehensive (loss) income	(48)	21	(210)	52
Balances as of end of period	105	340	105	340
Net Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Changes in Other Comprehensive income
Balances as of start of period	0	0	0	(1)
Reclassification for realized (gains) / losses into earnings				1
Net change in accumulated other comprehensive (loss) income	0	0	0	1
Balances as of end of period	0	0	0	0
Foreign Currency Translation Adjustments [Member]
Changes in Other Comprehensive income
Balances as of start of period	(1,027)	(809)	(754)	(682)
Net translation of investments in foreign operations	134	401	(422)	248
Net losses related to hedges of investment in foreign operations	(123)	(320)	160	(294)
Net change in accumulated other comprehensive (loss) income	11	81	(262)	(46)
Balances as of end of period	(1,016)	(728)	(1,016)	(728)
Net Unrealized Pension and Other Postretirement Benefit Losses [Member]
Changes in Other Comprehensive income
Balances as of start of period	(434)	(461)	(488)	(481)
Pension and other postretirement benefit losses	6	14	60	34
Net change in accumulated other comprehensive (loss) income	6	14	60	34
Balances as of end of period	$ (428)	$ (447)	$ (428)	$ (447)