Estimated Cost of Providing Uncompensated Care (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Health Care Trust Fund [Line Items]
Estimated cost of providing uncompensated care	$ 177,189	$ 172,713	$ 157,665
Charity Care
Health Care Trust Fund [Line Items]
Estimated cost of providing uncompensated care	131,890	145,350	129,820
Uninsured Discounts
Health Care Trust Fund [Line Items]
Estimated cost of providing uncompensated care	$ 45,299	$ 27,363	$ 27,845