Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (5,362)	$ (5,708)
Balance at end of period	(4,633)	(5,362)	$ (5,708)
Defined Benefit Pension and Postretirement Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(3,072)	(3,169)	(3,134)
Other comprehensive income (loss) before reclassifications	59	(448)	(331)
Amounts reclassified from accumulated other comprehensive income	486	545	296
Balance at end of period	(2,527)	(3,072)	(3,169)
Change in Cumulative Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(2,287)	(2,549)	(1,513)
Other comprehensive income (loss) before reclassifications	178	263	(1,002)
Amounts reclassified from accumulated other comprehensive income	(1)	(3)	(40)
Other Comprehensive Income (Loss) Attributable to Noncontrolling Interest	(1)	2	6
Balance at end of period	(2,111)	(2,287)	(2,549)
Net Gains and Losses on Cash Flow Hedging Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(3)	10	1
Other comprehensive income (loss) before reclassifications	15	(6)	(3)
Amounts reclassified from accumulated other comprehensive income	(7)	(7)	12
Other Comprehensive Income (Loss) Attributable to Noncontrolling Interest	5	(3)	10
Balance at end of period		(3)	10
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income	$ (478)	$ (535)	$ (268)