Segment Information - Schedule of Net Revenue Attributable to Insurance, Medicare, Medicaid, and Self-Pay as Percentage of Net Air Medical Revenues (Detail) - Air Medical [Member]	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Self-Pay [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	2.00%	0.00%
Medicaid [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	7.00%	9.00%
Medicare [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	23.00%	20.00%
Insurance [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	68.00%	71.00%