Equity, Income Tax Effects on Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Effects Related to Components of Other Comprehensive Income
Foreign currency translation adjustment, before-tax amount	$ 150	$ (64)	$ 76	$ (268)
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	9	15	17	29
Prior service credit, before-tax amount	(9)	(9)	(19)	(15)
Net gain (loss) on pension and other postretirement benefits, before-tax amount	0	6	(2)	342
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, before-tax amount	(3)	(10)	4	(9)
Net (gain) loss reclassified into income, before-tax amount	0	8	(3)	5
Net gain (loss) on cash flow hedges, before-tax amount	(3)	(2)	1	(4)
Other comprehensive income (loss), before-tax amount	147	(60)	75	70
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	6	10
Prior service credit, tax expense (benefit)	(5)	(4)	(8)	(6)
Net gain (loss) on pension and other postretirement benefits, tax expense (benefit)	(2)	1	(2)	119
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, tax expense (benefit)	0	(3)	2	(3)
Net (gain) loss reclassified into income, tax expense (benefit)	0	3	(1)	2
Net gain (loss) on cash flow hedges, tax expense (benefit)	0	0	1	(1)
Other comprehensive income (loss), tax expense (benefit)	(2)	1	(1)	118
Foreign currency translation adjustment, net	150	(64)	76	(268)
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	6	10	11	19
Prior service credit, net	(4)	(5)	(11)	(9)
Net gain (loss) on pension and other postretirement benefits, net	2	5	0	223
Derivative instruments designated and qualifying as cash flow hedges:
Net gain (loss) arising during the period, net	(3)	(7)	2	(6)
Net (gain) loss reclassified into income, net	0	5	(2)	3
Net gain (loss) on cash flow hedges, net	(3)	(2)	0	(3)
Other comprehensive income (loss)	$ 149	$ (61)	$ 76	$ (48)