Equity, Income Tax Effects on Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss) before income tax expense (benefit)		$ (549)	$ (881)	$ 663
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss), tax expense (benefit)		17	(164)	262
Other Comprehensive Income (Loss), Net of Tax
Reclassification from accumulated other comprehensive income (loss), current period, net of tax		19	0	18
Other comprehensive income (loss)		(566)	(717)	401
Accumulated Foreign Currency Adjustment [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax		(606)	(407)	(98)
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss), before reclassifications, tax expense (benefit)		0	0	0
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax		(606)	(407)	(98)
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Component [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax		50	(471)	367
Reclassification from accumulated other comprehensive income (loss), current period, before tax	[1]	62	34	57
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss), before reclassifications, tax expense (benefit)		15	(162)	125
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)		22	12	20
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax		35	(309)	242
Reclassification from accumulated other comprehensive income (loss), current period, net of tax		40	22	37
Accumulated Defined Benefit Plans Adjustment, Net Prior Service (Cost) Credit Component [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax		(22)	(1)
Reclassification from accumulated other comprehensive income (loss), current period, before tax	[1]	(40)	(40)	(33)
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss), before reclassifications, tax expense (benefit)		(8)	(1)
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)		(14)	(14)	(12)
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax		(14)	0
Reclassification from accumulated other comprehensive income (loss), current period, net of tax		(26)	(26)	(21)
Accumulated Defined Benefit Plans Adjustment, Plan Amendments Component [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax				371
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss), before reclassifications, tax expense (benefit)				130
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax				241
Accumulated Defined Benefit Plans Adjustment, Curtailment and Settlement Component [Member]
Other Comprehensive Income (Loss), before Tax
Reclassification from accumulated other comprehensive income (loss), current period, before tax	[1]	7	3	1
Other Comprehensive Income (Loss), Tax
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)		2	0	0
Other Comprehensive Income (Loss), Net of Tax
Reclassification from accumulated other comprehensive income (loss), current period, net of tax		5	3	1
Accumulated Defined Benefit Plans Adjustment [Member]
Other Comprehensive Income (Loss), before Tax
Reclassification from accumulated other comprehensive income (loss), current period, before tax		29	(3)	25
Other comprehensive income (loss) before income tax expense (benefit)		57	(475)	763
Other Comprehensive Income (Loss), Tax
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)		10	(2)	8
Other comprehensive income (loss), tax expense (benefit)		17	(165)	263
Other Comprehensive Income (Loss), Net of Tax
Reclassification from accumulated other comprehensive income (loss), current period, net of tax		19	(1)	17
Other comprehensive income (loss)		$ 40	(310)	500
Accumulated Net Gain (Loss) from Cash Flow Hedges [Member]
Other Comprehensive Income (Loss), before Tax
Other comprehensive income (loss), before reclassifications, before tax			(1)	(4)
Reclassification from accumulated other comprehensive income (loss), current period, before tax			2	2
Other comprehensive income (loss) before income tax expense (benefit)			1	(2)
Other Comprehensive Income (Loss), Tax
Other comprehensive income (loss), before reclassifications, tax expense (benefit)			0	(2)
Reclassification from accumulated other comprehensive income (loss), current period, tax expense (benefit)			1	1
Other comprehensive income (loss), tax expense (benefit)			1	(1)
Other Comprehensive Income (Loss), Net of Tax
Other comprehensive income (loss), before reclassifications, net of tax			(1)	(2)
Reclassification from accumulated other comprehensive income (loss), current period, net of tax			1	1
Other comprehensive income (loss)			$ 0	$ (1)

[1] (a)These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost, as further discussed in Note 13. Net periodic benefit cost is reflected in operating expenses and general and administrative expenses.