Segment Information - Schedule of Profit or Loss and Assets of Each of Company's Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Total operating revenues, net	$ 212,145	$ 195,543	$ 409,216	$ 374,511
Total segment selling, general and administrative expenses	11,660	10,024	20,988	18,290
Total net segment profit (loss)	29,821	39,709	57,797	61,696
Interest expense	(7,673)	(7,257)	(15,037)	(14,666)
Loss on debt extinguishment	(617)		(29,833)
Earnings before income taxes	21,700	32,525	13,187	47,255
Reportable operating segments [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	212,145	195,543	409,216	374,511
Total direct expenses	170,422	160,090	329,116	308,780
Total segment selling, general and administrative expenses	4,426	2,936	7,615	5,689
Total segment expenses	174,848	163,026	336,731	314,469
Total net segment profit (loss)	37,297	32,517	72,485	60,042
Reportable operating segments [Member] | Oil And Gas [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	128,044	120,970	254,019	233,801
Total direct expenses	103,450	97,824	200,824	190,697
Total segment selling, general and administrative expenses	1,489	1,027	2,523	1,940
Total net segment profit (loss)	23,105	22,119	50,672	41,164
Reportable operating segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	79,427	72,859	147,379	136,246
Total direct expenses	62,726	60,376	122,105	114,372
Total segment selling, general and administrative expenses	2,936	1,909	5,089	3,749
Total net segment profit (loss)	13,765	10,574	20,185	18,125
Reportable operating segments [Member] | Technical Services [Member]
Segment Reporting Information [Line Items]
Total operating revenues, net	4,674	1,714	7,818	4,464
Total direct expenses	4,246	1,890	6,187	3,711
Total segment selling, general and administrative expenses	1		3
Total net segment profit (loss)	427	(176)	1,628	753
Other, net [Member]
Segment Reporting Information [Line Items]
Total net segment profit (loss)	(73)	14,353	(1,055)	14,480
Unallocated Selling, General and Administrative Expenses [Member]
Segment Reporting Information [Line Items]
Total net segment profit (loss)	$ (7,234)	$ (7,088)	$ (13,373)	$ (12,601)