Revenue Recognition and Valuation Accounts - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Allowance for doubtful accounts	$ 5.1		$ 5.1		$ 5.2
Allowance for contractual discounts	114.0		114.0		103.6
Allowance for uncompensated care	31.6		31.6		41.9
Value of uncompensated care to patients	2.2	$ 2.3	4.7	$ 4.9
Estimated cost of charity services	0.5	$ 0.5	1.2	$ 1.1
Inventory valuation reserves	$ 16.6		$ 16.6		$ 15.4