Equity, Income Tax Effects on Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Tax Effects Related to Components of Other Comprehensive Income
Foreign currency translation adjustment, before-tax amount	$ (74)	$ (204)
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
Prior service credit, before-tax amount	(10)	(6)
Net gain (loss) on pension and other postretirement benefits, before-tax amount	(2)	336
Derivative instruments designated and qualifying as cash flow hedges:
Net gain arising during the period, before-tax amount	7	1
Net gain reclassified into income, before-tax amount	(3)	(3)
Net gain (loss) on cash flow hedges, before-tax amount	4	(2)
Other comprehensive income (loss), before-tax amount	(72)	130
Foreign currency translation adjustment, tax expense (benefit)	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
Prior service credit, tax expense (benefit)	(3)	(2)
Net gain (loss) on pension and other postretirement benefits, tax expense (benefit)	0	118
Derivative instruments designated and qualifying as cash flow hedges:
Net gain arising during the period, tax expense (benefit)	2	0
Net gain reclassified into income, tax expense (benefit)	(1)	(1)
Net gain (loss) on cash flow hedges, tax expense (benefit)	1	(1)
Other comprehensive income (loss) tax expense (benefit)	1	117
Foreign currency translation adjustment, net	(74)	(204)
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
Prior service credit, net	(7)	(4)
Net gain (loss) on pension and other postretirement benefits, net	(2)	218
Derivative instruments designated and qualifying as cash flow hedges:
Net gain arising during the period, net	5	1
Net gain reclassified into income, net	(2)	(2)
Net gain (loss) on cash flow hedges, net	3	(1)
Other comprehensive income (loss)	$ (73)	$ 13