Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Valuation Allowance for Deferred Tax Assets
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 70,227		$ 56,333		$ 52,567
Charges to costs and expenses (income)		9,037		13,894		3,766
Balance at end of period		79,264		70,227		56,333
Allowance for Doubtful Accounts Receivable
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 480,289	[1]	410,374	[1]	398,797
Charges to costs and expenses (income)				869,077	[1]	741,578
Write-off of uncollectible accounts				(799,162)	[1]	(730,001)
Balance at end of period	[1]			$ 480,289		$ 410,374

[1] Effective January 1, 2018, the Company adopted ASC 606 using a modified retrospective approach.  This schedule discloses allowance for doubtful accounts receivable for periods reported under ASC 605 only.