Accounts Receivable - Schedule of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for uncollectible accounts	$ 1,633	$ 77
Allowance for Doubtful Accounts [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	1,115
Provision for uncollectible accounts	1,633
Charged to other accounts	0
Deductions	(383)
Ending Balance	$ 2,365