Business Segments and Geographic Areas - Schedule of Profit or Loss and Assets of Each of Company's Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Total operating revenues	$ 210,760	$ 216,294	$ 212,145	$ 197,071	$ 281,227	$ 200,762	$ 195,543	$ 178,968	$ 836,270		$ 856,500		$ 646,686
Total segment selling, general and administrative expenses									43,171		38,820		39,051
Total net segment profit (loss)									111,640		119,284		62,931
Interest expense									(29,510)		(29,756)		(29,533)
Loss on debt extinguishment									(29,833)
Earnings before income taxes	11,651	28,277	21,700	(8,513)	18,674	24,212	32,525	14,730	53,115		90,141		34,049
Reportable Operating Segments [Member]
Segment Reporting Information [Line Items]
Total operating revenues									836,270		856,500		646,686
Total segment direct expenses									670,103		713,352		544,387
Total segment selling, general and administrative expenses									14,573		12,935		11,036
Total segment expenses									684,676		726,287		555,423
Total net segment profit (loss)									151,594		130,213		91,263
Reportable Operating Segments [Member] | Oil and Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues									516,909		489,055		424,514
Total segment direct expenses									411,679	[1]	393,251	[1]	360,400	[1]
Total segment selling, general and administrative expenses									4,615		4,059		3,736
Total net segment profit (loss)									100,615		91,745		60,378
Reportable Operating Segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues									300,212		277,884		211,148
Total segment direct expenses									243,573		231,880		175,944
Total segment selling, general and administrative expenses									9,801	[2]	8,875	[2]	7,300	[2]
Total net segment profit (loss)									46,838		37,129		27,904
Interest expense											(300)
Reportable Operating Segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues									19,149		89,561		11,024
Total segment direct expenses									14,851		88,221		8,043
Total segment selling, general and administrative expenses									157		1
Total net segment profit (loss)									4,141		1,339		2,981
Other, net [Member]
Segment Reporting Information [Line Items]
Other, net									(10,539)	[3]	15,569	[3]	334	[3]
Corporate [Member]
Segment Reporting Information [Line Items]
Unallocated selling, general and administrative costs									$ (28,597)		$ (26,207)		$ (28,015)

[1] Includes equity in loss of unconsolidated affiliate.

[2] Includes interest expense $0.3 million for the year ended December 31, 2013.

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