Equity, Income Tax Effects on Other Comprehensive Loss (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Tax Effects Related to Components of Other Comprehensive Loss
Foreign currency translation adjustment, before-tax amount	$ (366)	$ (74)
Amounts reclassified into income related to:
Net actuarial loss, before-tax amount	15	8
Prior service credit, before-tax amount	(10)	(10)
Net gain (loss) on pension and other postretirement benefits, before-tax amount	5	(2)
Derivative instruments designated and qualifying as cash flow hedges:
Net gain arising during the period, before-tax amount	0	7
Net gain reclassified into income, before-tax amount	0	(3)
Net gain on cash flow hedges, before-tax amount	0	4
Other comprehensive loss before income tax expense	(361)	(72)
Foreign currency translation adjustment, tax expense (benefit)	0	0
Amounts reclassified into income related to:
Net actuarial loss, tax expense (benefit)	5	3
Prior service credit, tax expense (benefit)	(3)	(3)
Net gain (loss) on pension and other postretirement benefits, tax expense (benefit)	2	0
Derivative instruments designated and qualifying as cash flow hedges:
Net gain arising during the period, tax expense (benefit)	0	2
Net gain reclassified into income, tax expense (benefit)	0	(1)
Net gain on cash flow hedges, tax expense (benefit)	0	1
Other comprehensive loss, tax expense (benefit)	2	1
Foreign currency translation adjustment, net	(366)	(74)
Amounts reclassified into income related to:
Net actuarial loss, net	10	5
Prior service credit, net	(7)	(7)
Net gain (loss) on pension and other postretirement benefits, net	3	(2)
Derivative instruments designated and qualifying as cash flow hedges:
Net gain arising during the period, net	0	5
Net gain reclassified into income, net	0	(2)
Net gain on cash flow hedges, net	0	3
Other comprehensive loss	$ (363)	$ (73)