Summary of Significant Accounting Policies - Allowance for Doubtful Accounts and Other Accounts Receivable Allowances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance For Doubtful Accounts Receivable Rollforward
Allowance, balance at the beginning	$ 8,046	$ 10,011	$ 5,945
Provision charged to income	1,917	1,106	4,625
Accounts written off, net of recoveries	(208)	(3,071)	(559)
Allowance, balance at ending	$ 9,755	$ 8,046	$ 10,011