Segment Information - Schedule of Profit or Loss and Assets of Each of the Company's Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Total operating revenues, net	$ 200,762	$ 170,857	$ 575,273	$ 469,462
Total direct expenses	160,731	141,706	468,428	394,496
Total segment selling, general and administrative expenses	9,785	9,784	28,075	28,292
Total direct and selling, general and administrative expenses	164,056	144,406	478,525	402,380
Total net segment profit (loss)	31,817	18,666	93,513	46,663
Interest expense	(7,768)	(7,488)	(22,434)	(22,128)
Earnings before income taxes	24,212	11,440	71,467	25,160
Reportable operating segments [Member]
Segment Reporting Information [Line Items]
Total segment selling, general and administrative expenses	3,497	2,700	9,186	7,884
Total net segment profit (loss)	36,706	26,451	96,748	67,082
Reportable operating segments [Member] | Oil And Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	125,931	114,949	359,732	312,322
Total direct expenses	99,919	94,563	290,616	263,829
Total segment selling, general and administrative expenses	1,036	1,002	2,976	2,810
Total net segment profit (loss)	24,976	19,384	66,140	45,683
Reportable operating segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	73,188	54,004	209,434	150,557
Total direct expenses	58,924	45,308	173,296	125,311
Total segment selling, general and administrative expenses	2,461	1,698	6,210	5,073
Total net segment profit (loss)	11,803	6,998	29,928	20,173
Reportable operating segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	1,643	1,904	6,107	6,583
Total direct expenses	1,716	1,835	5,427	5,356
Total segment selling, general and administrative expenses				1
Total net segment profit (loss)	(73)	69	680	1,226
Other, net [Member]
Segment Reporting Information [Line Items]
Total net segment profit (loss)	1,561	(439)	16,041	614
Unallocated S,G & A [Member]
Segment Reporting Information [Line Items]
Total net segment profit (loss)	$ (6,424)	$ (7,084)	$ (19,025)	$ (20,408)