Segment Information - Schedule of Financial Information Concerning Reportable Operating Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total operating revenues, net	$ 151,890	$ 160,370
Total direct expenses	156,874	156,226
Total segment selling, general and administrative expenses	24,869	15,459
Total net segment profit	(28,543)	(12,231)
Interest expense	(8,166)	(8,197)
Loss before income taxes	(38,349)	(21,473)
Reportable Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	151,890	160,370
Total direct expenses	155,513	156,226
Total segment selling, general and administrative expenses	8,201	8,458
Total segment direct and selling, general and administrative expenses	163,714	164,684
Total net segment profit	(11,824)	(4,314)
Reportable Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	84,946	95,640
Total direct expenses	89,968	96,507
Total segment selling, general and administrative expenses	4,761	4,921
Total net segment profit	(9,783)	(5,788)
Reportable Operating Segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	56,646	56,988
Total direct expenses	57,081	53,832
Total segment selling, general and administrative expenses	3,292	3,167
Total net segment profit	(3,727)	(11)
Reportable Operating Segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	10,298	7,742
Total direct expenses	8,464	5,887
Total segment selling, general and administrative expenses	148	370
Total net segment profit	1,686	1,485
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Other, net	(91)	(1,961)
Interest expense	(8,166)	(8,197)
Corporate [Member]
Segment Reporting Information [Line Items]
Unallocated selling, general and administrative costs	$ (18,268)	$ (7,001)