Valuation and Qualifying Accounts (Detail) - Allowance For Doubtful Accounts - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	[1]	$ 8,385	$ 8,738	$ 12,140
Additions Charged to Costs and Expenses	[1]	13,530	25,128	9,627
Deductions	[1]	(2,521)	(25,481)	(13,029)
Balance at End of Period	[1]	$ 19,394	$ 8,385	$ 8,738

[1] These amounts include reserves for bad debts