Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss, capital loss and tax credit carry-forwards	$ 259	$ 285
Landfill and environmental remediation liabilities	121	116
Miscellaneous and other reserves, net	96	355
Subtotal	476	756
Valuation allowance	(264)	(292)
Deferred tax liabilities:
Property and equipment	(595)	(728)
Goodwill and other intangibles	(865)	(1,218)
Net deferred tax liabilities	(1,248)	$ (1,482)
Increase (decrease) valuation allowance	$ (28)