Description of Business and Summary of Significant Accounting Policies - Cash Paid for Interest (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplemental Cash Flow Information [Abstract]
Debt interest paid	$ 63,325	$ 60,780	$ 53,978
Capitalized interest	(6,645)	(1,721)	(169)
Cash paid for interest, net of capitalized interest	$ 56,680	$ 59,059	$ 53,809