Valuation Accounts - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts	$ 6.3		$ 6.3		$ 6.1
Value of services to patients who are unable to pay	1.6	$ 1.7	3.5	$ 3.3
Estimated cost of providing charity services	0.3	$ 0.4	0.8	$ 0.8
Valuation reserves related to obsolescence and slow moving inventory	19.4		19.4		17.9
Air Medical [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for contractual discounts against outstanding accounts receivable	140.5		140.5		123.8
Allowance for uncompensated care against outstanding accounts receivable	$ 45.5		$ 45.5		$ 51.9