Uncompensated Care (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Health Care Trust Fund [Line Items]
Total uncompensated care	$ 1,768,401	$ 1,453,790	$ 1,203,034
Uncompensated care, percentage	100.00%	100.00%	100.00%
Charity Care
Health Care Trust Fund [Line Items]
Total uncompensated care	$ 887,136	$ 733,585	$ 506,571
Uncompensated care, percentage	50.00%	50.00%	42.00%
Uninsured Discounts
Health Care Trust Fund [Line Items]
Total uncompensated care	$ 881,265	$ 720,205	$ 696,463
Uncompensated care, percentage	50.00%	50.00%	58.00%