Revenue Recognition and Valuation Accounts - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts	$ 6.1	$ 6.0
Value of uncompensated care services	2.5		$ 2.5
Estimated cost of providing charity services	0.6		$ 0.6
Valuation reserves related to obsolescence and slow moving inventory	17.7	17.3
Air Medical [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for contractual discounts against outstanding accounts receivable	107.6	111.9
Allowance for uncompensated care against outstanding accounts receivable	$ 48.0	$ 46.3