Valuation Accounts - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts	$ 6.1		$ 6.1
Allowance for contractual discounts against outstanding accounts receivable	116.5		123.8
Allowance for uncompensated care against outstanding accounts receivable	51.6		51.9
Value of services to patients who are unable to pay	1.9	$ 1.5
Estimated cost of providing charity services	0.5	$ 0.4
Valuation reserves related to obsolescence and slow moving inventory	18.4		17.9
Air Medical [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for contractual discounts against outstanding accounts receivable	116.5		123.8
Allowance for uncompensated care against outstanding accounts receivable	$ 51.6		$ 51.9