Equity, Income Tax Effects on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Tax Effects Related to Components of Other Comprehensive Income (Loss)
Foreign currency translation adjustment, before-tax amount	$ 197	$ 150	$ (169)	$ 76
Amounts reclassified into income related to:
Net actuarial loss, before-tax amount	16	9	31	17
Prior service credit, before-tax amount	(10)	(9)	(20)	(19)
Net gain (loss) on pension and other postretirement benefits, before-tax amount	6	0	11	(2)
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, before-tax amount	0	(3)	0	4
Net gain reclassified into income, before-tax amount			0	(3)
Net gain (loss) on cash flow hedges, before-tax amount	0	(3)	0	1
Other comprehensive income (loss) before income tax expense (benefit)	203	147	(158)	75
Foreign currency translation adjustment, tax expense (benefit)	0	0	0	0
Amounts reclassified into income related to:
Net actuarial loss, tax expense (benefit)	6	3	11	6
Prior service credit, tax expense (benefit)	(4)	(5)	(7)	(8)
Net gain (loss) on pension and other postretirement benefits, tax expense (benefit)	2	(2)	4	(2)
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, tax expense (benefit)	0	0	0	2
Net gain reclassified into income, tax expense (benefit)			0	(1)
Net gain (loss) on cash flow hedges, tax expense (benefit)	0	0	0	1
Other comprehensive income (loss), tax expense (benefit)	2	(2)	4	(1)
Foreign currency translation adjustment, net	197	150	(169)	76
Amounts reclassified into income related to:
Net actuarial loss, net	10	6	20	11
Prior service credit, net	(6)	(4)	(13)	(11)
Net gain (loss) on pension and other postretirement benefits, net	4	2	7	0
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, net	0	(3)	0	2
Net gain reclassified into income, net			0	(2)
Net gain (loss) on cash flow hedges, net	0	(3)	0	0
Other comprehensive income (loss)	$ 201	$ 149	$ (162)	$ 76