Segment Information - Schedule of Financial Information Concerning Reportable Operating Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Total operating revenues	$ 204,197		$ 197,071
Total segment selling, general and administrative expenses	11,237		9,328
Total net segment profit	23,692		27,976
Interest expense	(7,170)		(7,364)
Loss on debt extinguishment			(29,216)
Earnings (loss) before income taxes	16,984		(8,513)
Reportable Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating revenues	204,197		197,071
Total segment direct expenses	169,275	[1]	158,694	[1]
Total segment selling, general and administrative expenses	3,902		3,189
Total direct and selling, general and administrative expenses	173,177		161,883
Total net segment profit	31,020		35,188
Reportable Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues	120,396		125,975
Total segment direct expenses	100,331	[1],[2]	97,374	[1],[2]
Total segment selling, general and administrative expenses	1,159		1,034
Total net segment profit	18,906		27,567
Reportable Operating Segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues	72,385		67,952
Total segment direct expenses	60,039	[1]	59,379	[1]
Total segment selling, general and administrative expenses	2,629		2,153
Total net segment profit	9,717		6,420
Reportable Operating Segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues	11,416		3,144
Total segment direct expenses	8,905	[1]	1,941	[1]
Total segment selling, general and administrative expenses	114		2
Total net segment profit	2,397		1,201
Other, net [Member]
Segment Reporting Information [Line Items]
Other, net	469	[3]	(982)	[3]
Unallocated Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Unallocated selling, general and administrative costs	$ (7,335)	[1]	$ (6,139)	[1]

[1] Included in segment direct expenses and unallocated selling, general, and administrative costs are the depreciation and amortization expense amounts below:

[2] Includes Equity in loss of unconsolidated affiliate.

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