Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue from External Customer [Line Items]
Value of uncompensated care services qualified as charity care	$ 1.6	$ 1.7	$ 3.5	$ 3.3
Estimated cost of providing charity services	0.3	$ 0.4	$ 0.8	$ 0.8
Percentage of reserve for receivables outstanding more than nine months (percent)			100.00%
Oil and Gas [Member]
Revenue from External Customer [Line Items]
Accounts receivable, net	86.2		$ 86.2		$ 74.1
Air Medical [Member]
Revenue from External Customer [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
Accounts receivable, net	95.8		95.8		90.2
Technical Services [Member]
Revenue from External Customer [Line Items]
Accounts receivable, net	$ 1.3		$ 1.3		$ 4.1
Minimum [Member]
Revenue from External Customer [Line Items]
Accounts receivable invoice term			30 days
Minimum [Member] | Oil and Gas [Member]
Revenue from External Customer [Line Items]
Typical contract length			1 year
Minimum [Member] | Air Medical [Member]
Revenue from External Customer [Line Items]
Contract termination notice period			30 days
Maximum [Member]
Revenue from External Customer [Line Items]
Performance obligations satisfaction period to recognize revenue			30 days
Accounts receivable invoice term			60 days
Maximum [Member] | Oil and Gas [Member]
Revenue from External Customer [Line Items]
Typical contract length			7 years
Maximum [Member] | Air Medical [Member]
Revenue from External Customer [Line Items]
Contract termination notice period			180 days