Accounts Receivable - Allowance for Doubtful Accounts Related to Accounts Receivable (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Allowance for Doubtful Accounts Receivable [Roll Forward]
Allowance for doubtful accounts beginning of period	$ 21,903	$ 23,842
Provision for bad debts	13,729	13,022
Write-offs	(10,396)	(14,464)
Allowance for doubtful accounts end of period	$ 25,236	$ 22,400