Income Taxes (Components of Deferred Income Tax Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax assets:
Accrued expenses	$ 68,706	$ 37,465
Compensation	28,994	16,924
Interest rate and fuel hedges		7,475
Contingent liabilities	20,653	17,636
Finance costs	10,374
Tax credits and loss carryforwards	43,596
Other	10,022	9,648
Gross deferred income tax assets	182,345	89,148
Less: Valuation allowance	(14,567)
Net deferred income tax assets	167,778	89,148
Deferred income tax liabilities:
Goodwill and other intangibles	(383,205)	(158,093)
Property and equipment	(460,878)	(288,953)
Landfill closure/post-closure	(87,006)	(37,185)
Prepaid expenses	(13,244)	(7,683)
Interest rate and fuel hedges	(2,109)
Total deferred income tax liabilities	(946,442)	(491,914)
Net deferred income tax liability	$ (778,664)	$ (402,766)