Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (2,059)	$ (2,076)	$ (2,356)	$ (2,356)	$ (2,356)	$ (2,356)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						542	$ (299)	$ (630)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax						(295)	(135)	(24)
Net change	(2)	23	287	310	308	316	336	(599)
Ending Balance	$ (2,063)	$ (2,059)	(2,076)	(2,059)	(2,063)	(2,057)	(2,356)
Unrealized Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(1,798)	(1,798)	(1,798)	(1,798)	(1,332)	(628)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax						542	(299)	(630)
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax						(311)	(167)	(74)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax
Net change							(466)	(704)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent						231
Ending Balance						(1,567)	(1,798)	(1,332)
Pension and Other Post retirement Benefit Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(571)	(571)	(571)	(571)	(1,379)	(1,492)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						20	29	9
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax						58	779	104
Net change						78	808	113
Ending Balance						(493)	(571)	(1,379)
Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			13	13	13	13	9	4
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax						(4)	3	41
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax						(6)	1	(36)
Net change						(10)	4	5
Ending Balance						3	13	9
Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(2,356)	(2,356)	(2,356)	(2,356)	(2,702)	(2,116)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax						52	780	68
Net change			$ 280	$ 297	$ 293	299	346	(586)
Ending Balance						$ (2,057)	$ (2,356)	$ (2,702)