Summary of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Accrued compensation	$ 9,441	$ 20,651
Other reserves	6,736	8,580
Tax credit carryforwards	3,411	1,694
Operating loss carryforwards	1,388	1,399
Total gross deferred income taxes	20,976	32,324
Valuation allowances	(1,681)	(456)
Total deferred tax assets	19,295	31,868
Prepaids	(3,587)	(3,401)
Other receivables	(2,462)	(3,051)
Property and equipment	(79,224)	(105,905)
Goodwill	(55,117)	(84,170)
Total deferred tax liabilities	(140,390)	(196,527)
Total deferred taxes	$ (121,095)	$ (164,659)