Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Doubtful Accounts Receivable
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 398,797	$ 324,648	$ 395,035
Charges to costs and expenses (income)	741,578	741,273	698,983
Acquisitions of business			506
Write-off of uncollectible accounts	(730,001)	(667,124)	(769,876)
Balance at end of period	410,374	398,797	324,648
Valuation Allowance for Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	52,567	52,764	46,841
Charges to costs and expenses (income)	3,766	(197)	5,923
Balance at end of period	$ 56,333	$ 52,567	$ 52,764