Revenue Recognition and Valuation Accounts - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Valuation and Qualifying Accounts [Abstract]
Allowance for doubtful accounts	$ 1.4		$ 1.4
Allowance for contractual discounts	98.3		96.6
Allowance for uncompensated care	36.3		41.9
Value of uncompensated care to patients	2.7	2.4
Estimated cost of charity services	0.6	0.6
Contractual period of services	3 years
Contract termination period	90 days
Termination fee	13.5
Inventory valuation reserves	$ 13.7		$ 13.5