Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Deferred income taxes	$ 192	$ (51)	$ (58)
Federal net operating loss carryforwards net of valuation allowances	19
Foreign net operating loss carryforwards	889
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	0	$ 0	$ 1
Deferred Tax Liabilities, Undistributed Foreign Earnings	1,300
Internal Revenue Service (IRS)
Income Tax Disclosure [Line Items]
Federal net operating loss carryforwards net of valuation allowances	$ 3,200
Internal Revenue Service (IRS) | Maximum
Income Tax Disclosure [Line Items]
Operating loss carryforwards expiration period	Jan. 01, 2031
Other Tax [Member]
Income Tax Disclosure [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 98
Provision adjustment due to corporate tax rate change [Member]
Income Tax Disclosure [Line Items]
Deferred income taxes	317
Provision adjustment due to anticipated repatriation of foreign earnings [Member]
Income Tax Disclosure [Line Items]
Deferred income taxes	$ (104)