Quarterly Results - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Implementation of EHR applications
Quarterly Financial Information [Line Items]
Unfavorable pre-tax reduction		$ 8.0	$ 6.9	$ 8.3		$ 7.9	$ 7.1	$ 8.9
Unfavorable after-tax reduction		$ 5.0	$ 4.4	$ 5.3		$ 4.5	$ 3.9	$ 4.9
Tax reduction per diluted share		$ 0.05	$ 0.05	$ 0.05		$ 0.04	$ 0.04	$ 0.05
EHR applications
Quarterly Financial Information [Line Items]
Tax reduction per diluted share	$ 0.03				$ 0.08
Favorable pre-tax reduction	$ 4.9				$ 13.8
Favorable after-tax reduction	$ 3.1				$ 8.6
Resulting from the gain realized on the sale of a non-operating investment
Quarterly Financial Information [Line Items]
Tax reduction per diluted share								$ 0.07
Favorable pre-tax reduction								$ 10.1
Favorable after-tax reduction								$ 6.3
Related to extinguishment of debt from the early redemption of previously outstanding $250 million 7.00% senior unsecured notes and the repayment of $550 million of previously outstanding Term Loan B facility
Quarterly Financial Information [Line Items]
Unfavorable pre-tax reduction						$ 36.2
Unfavorable after-tax reduction						$ 22.7
Tax reduction per diluted share						$ 0.23
Incurred in connection with the previously disclosed $65 million settlement of the Garden City matter
Quarterly Financial Information [Line Items]
Unfavorable pre-tax reduction						$ 44.0
Unfavorable after-tax reduction						$ 27.6
Tax reduction per diluted share						$ 0.27
Professional and general liability self-insurance reserves
Quarterly Financial Information [Line Items]
Tax reduction per diluted share					$ 0.12
Favorable pre-tax reduction					$ 19.7
Favorable after-tax reduction					$ 11.7