Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred income tax liabilities:
Property and equipment	$ (161,491)	$ (214,902)
Goodwill	(49,407)	(83,097)
Other intangibles	(26,676)	(33,566)
Customer holdbacks	(36,218)	(16,424)
Other book/tax accounting method differences	(15,154)	(24,817)
Total deferred income tax liabilities	(288,946)	(372,806)
Deferred income tax assets:
Accruals and reserves	21,419	21,681
Accrued insurance	0	79,630
Stock and incentive compensation and pension withdrawal liabilities	17,676	58,744
Net operating loss carryforwards	62,925	37,362
Tax credits	48,516	1,613
Other	4,747	5,933
Subtotal	155,283	204,963
Valuation allowance	(19,328)	(14,991)	$ (16,100)
Total deferred income tax assets	135,955	189,972
Total net deferred income tax liabilities	$ (152,991)	$ (182,834)