Summary of Significant Accounting Policies - Reconciliation of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable [Roll Forward]
Beginning balance	$ 5,645	$ 6,460	$ 11,655
Provision	2,398	992	2,143
Write-off of uncollectible amounts, net of recoveries	(2,315)	(1,807)	(7,338)
Ending balance	$ 5,728	$ 5,645	$ 6,460