Equity, Income Tax Effects on Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Tax Effects Related to Components of Other Comprehensive Income
Foreign currency translation adjustment, before-tax amount	$ (274)	$ 181	$ (198)	$ (87)
Pension and other postretirement benefits:
Gain arising during the period related to plan amendments, before-tax amount			0	328
Amounts reclassified into income related to:
Net actuarial loss, before-tax amount	8	14	25	43
Prior service credit, before-tax amount	(11)	(9)	(30)	(24)
Net gain (loss) on pension and other postretirement benefits, before-tax amount	(3)	5	(5)	347
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, before-tax amount	(5)	3	(1)	(6)
Net (gain) loss reclassified into income, before-tax amount	5	(6)	2	(1)
Net gain (loss) on cash flow hedges, before-tax amount	0	(3)	1	(7)
Other comprehensive income (loss), before-tax amount	(277)	183	(202)	253
Foreign currency translation adjustment, tax expense (benefit)	0	0	0	0
Pension and other postretirement benefits:
Gain arising during the period related to plan amendments, tax expense (benefit)			0	115
Amounts reclassified into income related to:
Net actuarial loss, tax expense (benefit)	3	5	9	15
Prior service credit, tax expense (benefit)	(3)	(3)	(11)	(9)
Net gain (loss) on pension and other postretirement benefits, tax expense (benefit)	0	2	(2)	121
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, tax expense (benefit)	(2)	1	0	(2)
Net (gain) loss reclassified into income, tax expense (benefit)	2	(2)	1	0
Net gain (loss) on cash flow hedges, tax expense (benefit)	0	(1)	1	(2)
Other comprehensive income (loss), tax expense (benefit)	0	1	(1)	119
Foreign currency translation adjustment, net	(274)	181	(198)	(87)
Pension and other postretirement benefits:
Gain arising during the period related to plan amendments, net			0	213
Amounts reclassified into income related to:
Net actuarial loss, net	5	9	16	28
Prior service credit, net	(8)	(6)	(19)	(15)
Net gain (loss) on pension and other postretirement benefits, net	(3)	3	(3)	226
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, net	(3)	2	(1)	(4)
Net (gain) loss reclassified into income, net	3	(4)	1	(1)
Net gain (loss) on cash flow hedges, net	0	(2)	0	(5)
Other comprehensive income (loss)	$ (277)	$ 182	$ (201)	$ 134