Allowance for Doubtful Accounts - Schedule of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Receivables [Abstract]
Balance at Beginning of Period	$ 6,472	$ 9,678
Charged to Expense	11,412	10,835
Deductions	(12,089)	(13,036)
Balance at End of Period	$ 5,795	$ 7,477