Revenue Recognition and Valuation Accounts - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Revenue Recognition And Valuation Accounts [Abstract]
Allowance for doubtful accounts	$ 0.1		$ 0.1		$ 0.1
Allowance for contractual discounts	67.4	57.1	67.4	57.1	54.6
Allowance for uncompensated care	55.5	51.3	55.5	51.3	48.0
Value of uncompensated care to patients	2.1	1.8	6.5	4.0
Estimated cost of charity services	1.0	0.5	2.5	1.4
Contractual period of services			3 years
Contract termination period			90 days
Termination fee			13.5
Inventory valuation reserves	$ 11.9		$ 11.9		$ 12.4