Equity, Income Tax Effects on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss) before income tax expense (benefit)	$ 125	$ (361)
Other Comprehensive Income (Loss), Tax
Income tax expense (benefit) related to items of other comprehensive income (loss)	(7)	2
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss)	132	(363)
Accumulated Foreign Currency Adjustment [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax	122	(366)
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss) before reclassifications, tax expense (benefit)	0	0
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax	122	(366)
Accumulated Defined Benefit Plans Adjustment, Miscellaneous Gain Component [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax	0	0
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss) before reclassifications, tax expense (benefit)	(8)	0
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax	8	0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Component [Member]
Other Comprehensive Income (Loss), before Tax
Reclassification from accumulated other comprehensive income (loss), current period, before tax	12	15
Other Comprehensive Income (Loss), Tax
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)	4	5
Other Comprehensive Income (Loss), Net of Tax
Reclassification from accumulated other comprehensive income (loss), current period, net of tax	8	10
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Cost (Credit) Component [Member]
Other Comprehensive Income (Loss), before Tax
Reclassification from accumulated other comprehensive income (loss), current period, before tax	(9)	(10)
Other Comprehensive Income (Loss), Tax
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)	(3)	(3)
Other Comprehensive Income (Loss), Net of Tax
Reclassification from accumulated other comprehensive income (loss), current period, net of tax	(6)	(7)
Accumulated Defined Benefit Plans Adjustment [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss) before income tax expense (benefit)	3	5
Other Comprehensive Income (Loss), Tax
Income tax expense (benefit) related to items of other comprehensive income (loss)	(7)	2
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss)	$ 10	$ 3