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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Insurance [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	72.00%	69.00%	71.00%	70.00%
Medicare [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	18.00%	18.00%	18.00%	18.00%
Medicaid [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	8.00%	9.00%	9.00%	10.00%
Self Pay [Member]
Segment Reporting Information [Line Items]
Percentage of net Air Medical revenues	2.00%	4.00%	2.00%	2.00%