Segment Information - Schedule of Financial Information Concerning Reportable Operating Segments (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Total operating revenues, net		$ 158,093	$ 214,733	$ 489,245	$ 617,477
Total direct expenses		144,938	182,064	449,909	520,099
Total segment selling, general and administrative expenses		13,381	11,575	36,832	34,859
Total		(509)	21,184	6,084	62,508
Interest expense		(7,719)	(7,366)	(22,792)	(21,691)
(Loss) earnings before income taxes		(7,766)	14,290	(15,137)	42,318
Reportable Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net		158,093	214,733	489,245	617,477
Total direct expenses	[1]	145,136	182,139	450,183	520,348
Total segment selling, general and administrative expenses		5,027	3,929	13,894	11,841
Total segment expenses		150,163	186,068	464,077	532,189
Total		7,930	28,665	25,168	85,288
Reportable Operating Segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net		74,482	85,516	220,089	239,543
Total direct expenses	[1]	56,562	65,474	172,603	189,089
Total segment selling, general and administrative expenses		3,056	2,302	8,293	7,458
Total		14,864	17,740	39,193	42,996
Reportable Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net		77,551	121,190	249,173	354,425
Total direct expenses	[1],[2]	82,832	109,500	262,148	310,093
Total segment selling, general and administrative expenses		1,705	1,397	4,838	3,831
Total		(6,986)	10,293	(17,813)	40,501
Reportable Operating Segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net		6,060	8,027	19,983	23,509
Total direct expenses	[1]	5,742	7,165	15,432	21,166
Total segment selling, general and administrative expenses		266	230	763	552
Total		52	632	3,788	1,791
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Other, net	[3]	377	637	5,425	1,739
Interest expense		(7,719)	(7,366)	(22,792)	(21,691)
Unallocated Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Unallocated selling, general and administrative costs	[1]	$ (8,354)	$ (7,646)	$ (22,938)	$ (23,018)

[1] Included in direct expenses and unallocated selling, general, and administrative costs are the depreciation and amortization expense amounts below: Depreciation and Amortization Expense Quarter Ended Nine Months Ended September 30, September 30, 2016 2015 2016 2015 Segment Direct Expense: Oil and Gas $ 10,616 $ 11,194 $ 30,558 $ 32,797 Air Medical 5,267 4,100 14,654 12,948 Technical Services 141 130 426 390 Total $ 16,024 $ 15,424 $ 45,638 $ 46,135 Unallocated SG&A $ 2,269 $ 2,376 $ 7,416 $ 8,177

[2] Includes Equity in loss of unconsolidated affiliate.

[3] Consists of gains on disposition of property and equipment, and other income.