Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for Doubtful Accounts Receivable
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 395,035	$ 311,387	$ 253,405
Charges to costs and expenses	698,983	1,127,216	726,671
Acquisitions of business	506		5,632
Write-off of uncollectible accounts	(769,876)	(1,043,568)	(674,321)
Balance at end of period	324,648	395,035	311,387
Valuation Allowance for Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	46,841	44,511	42,143
Charges to costs and expenses	5,923	2,330	2,368
Balance at end of period	$ 52,764	$ 46,841	$ 44,511