Supplemental Equity and Comprehensive Income Information - AOCI rf (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent, Beginning Balance			$ 13,109
Other comprehensive income (loss), before tax:
Stockholders' Equity Attributable to Parent, Ending Balance	$ 12,186		12,186
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent, Beginning Balance	(6,233)	$ (3,666)	(6,289)	$ (3,913)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(187)	(440)	(99)	(315)
Amounts reclassified out	79	98	283	280
Total other comprehensive income (loss), before tax	(108)	(342)	184	(35)
Tax effect	(126)	(125)	(362)	(185)
Total other comprehensive income (loss), net of tax	(234)	(467)	(178)	(220)
Impact From Purchase Of Subsidiary Shares		25		25
Stockholders' Equity Attributable to Parent, Ending Balance	(6,467)	(4,108)	(6,467)	(4,108)
Cumulative Translation Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent, Beginning Balance	(1,264)	(57)	(1,095)	(188)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	(477)	(537)	(533)	(403)
Total other comprehensive income (loss), before tax	(477)	(537)	(533)	(403)
Tax effect	6	(56)	(107)	(59)
Total other comprehensive income (loss), net of tax	(471)	(593)	(640)	(462)
Impact From Purchase Of Subsidiary Shares		41		41
Stockholders' Equity Attributable to Parent, Ending Balance	(1,735)	(609)	(1,735)	(609)
Defined Benefit Pension and Postretirement Plans Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent, Beginning Balance	(5,106)	(3,594)	(5,293)	(3,715)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	233		257
Amounts reclassified out	134	89	399	272
Total other comprehensive income (loss), before tax	367	89	656	272
Tax effect	(131)	(30)	(233)	(92)
Total other comprehensive income (loss), net of tax	236	59	423	180
Impact From Purchase Of Subsidiary Shares		(16)		(16)
Stockholders' Equity Attributable to Parent, Ending Balance	(4,870)	(3,551)	(4,870)	(3,551)
Debt and equity security gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent, Beginning Balance				(2)
Other comprehensive income (loss), before tax:
Amounts before reclassifications		(1)		2
Total other comprehensive income (loss), before tax		(1)		2
Tax effect				(1)
Total other comprehensive income (loss), net of tax		(1)		1
Stockholders' Equity Attributable to Parent, Ending Balance		(1)		(1)
Cash flow hedging instruments gains (losses)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Stockholders' Equity Attributable to Parent, Beginning Balance	137	(15)	99	(8)
Other comprehensive income (loss), before tax:
Amounts before reclassifications	57	98	177	86
Amounts reclassified out	(55)	9	(116)	8
Total other comprehensive income (loss), before tax	2	107	61	94
Tax effect	(1)	(39)	(22)	(33)
Total other comprehensive income (loss), net of tax	1	68	39	61
Stockholders' Equity Attributable to Parent, Ending Balance	$ 138	$ 53	$ 138	$ 53