Business Segments and Geographic Areas (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment operating revenues
Total operating revenues									$ 646,686	$ 539,626	$ 516,935
Segment direct expenses
Total direct expenses									543,524	469,740	443,702
Segment selling, general and administrative expenses
Total selling, general and administrative expenses									11,036	8,757	9,612
Total direct and selling, general and administrative expenses									555,423	478,497	453,314
Net segment profit
Total	177,224	170,857	160,554	138,051	138,434	145,576	135,976	119,640	62,931	35,215	43,325
Other, net									334	543	417
Interest expense									(29,533)	(27,974)	(19,389)
Loss on debt restructuring											(9,521)
Earnings before income taxes	8,889	11,440	10,090	3,630	5,363	5,969	1,206	(4,452)	34,049	8,086	14,593
Oil and Gas [Member]
Segment operating revenues
Total operating revenues									424,514	355,406	345,402
Segment direct expenses
Total direct expenses									360,400	310,281	290,106
Segment selling, general and administrative expenses
Total selling, general and administrative expenses									3,736	3,506	4,594
Net segment profit
Total									60,378	41,619	50,702
Air Medical [Member]
Segment operating revenues
Total operating revenues									211,148	171,669	160,517
Segment direct expenses
Total direct expenses									175,944	151,503	145,356
Segment selling, general and administrative expenses
Total selling, general and administrative expenses									7,300	5,198	4,987
Net segment profit
Total									27,904	14,968	10,174
Technical Services [Member]
Segment operating revenues
Total operating revenues									11,024	12,551	11,016
Segment direct expenses
Total direct expenses									8,043	7,956	8,240
Segment selling, general and administrative expenses
Total selling, general and administrative expenses										53	31
Net segment profit
Total									2,981	4,542	2,745
Unallocated [Member]
Segment selling, general and administrative expenses
Total selling, general and administrative expenses									$ (28,015)	$ (25,612)	$ (20,535)