Business Segments and Geographic Areas - Schedule of Financial Information Concerning Reportable Operating Segments (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total operating revenues		$ 144,853	$ 158,093	$ 167,136	$ 164,016	$ 186,751	$ 214,733	$ 198,547	$ 204,197	$ 634,098	$ 804,228	$ 836,270
Total segment direct expenses										592,550	687,050	670,007
Total segment selling, general and administrative expenses										44,418	46,422	43,171
Total net segment profit										224	70,111	111,640
Interest expense										(30,644)	(29,066)	(29,510)
Loss on debt extinguishment												(29,833)
(Loss) earnings before income taxes		$ (12,012)	$ (7,766)	$ 117	$ (7,488)	$ 938	$ 14,290	$ 11,044	$ 16,984	(27,149)	43,256	53,115
Reportable Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating revenues										634,098	804,228	836,270
Total segment direct expenses										592,399	687,356	670,103
Total segment selling, general and administrative expenses										18,808	17,771	14,573
Total segment expenses										611,207	705,127	684,676
Total net segment profit										22,891	99,101	151,594
Reportable Operating Segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues										281,868	312,775	300,212
Total segment direct expenses										227,877	246,487	243,573
Total segment selling, general and administrative expenses										10,968	10,455	9,801
Total net segment profit										43,023	55,833	46,838
Reportable Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues										324,129	459,611	516,909
Total segment direct expenses	[1]									344,640	411,757	411,679
Total segment selling, general and administrative expenses										6,739	6,511	4,615
Total net segment profit										(27,250)	41,343	100,615
Reportable Operating Segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues										28,101	31,842	19,149
Total segment direct expenses										19,882	29,112	14,851
Total segment selling, general and administrative expenses										1,101	805	157
Total net segment profit										7,118	1,925	4,141
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Other, net	[2]									6,214	1,872	(10,539)
Interest expense										(30,644)	(29,066)	(29,510)
Corporate [Member]
Segment Reporting Information [Line Items]
Unallocated selling, general and administrative costs										$ (25,610)	$ (28,651)	$ (28,597)

[1] Includes equity in gain/loss of unconsolidated affiliate.

[2] Includes gains on disposition of property and equipment, asset impairments, and other income.