Business Segments and Geographic Areas (Tables)

12 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Schedule of Accounts Receivable and Revenue by Major Customers by Reporting Segments

The customers, individually or considered as a group under common ownership, which accounted for greater than 10% of accounts receivable or 10% of operating revenues during the periods reflected were as follows:

	Accounts Receivable						Operating Revenues
	December 31,						Years Ended December 31,
	2016			2015			2016			2015			2014
Oil and Gas segment:
Customer A		8	%		6	%		14	%		15	%		17	%
Customer B		8	%		9	%		10	%		11	%		13	%
Air Medical &
Technical Services segments:
Customer C		13	%		15	%		5	%		9	%		10	%

Schedule of Profit or Loss and Assets of Each of Company's Reportable Segments

The following table shows information about the profit or loss and assets of each of the Company’s reportable segments for the years ended December 31, 2016, 2015, and 2014.

	Year Ended December 31,
	2016			2015			2014
	(Thousands of dollars)
Segment operating revenues
Oil and Gas	$	324,129		$	459,611		$	516,909
Air Medical		281,868			312,775			300,212
Technical Services		28,101			31,842			19,149
Total operating revenues		634,098			804,228			836,270
Segment direct expenses
Oil and Gas(1)		344,640			411,757			411,679
Air Medical		227,877			246,487			243,573
Technical Services		19,882			29,112			14,851
Total segment direct expenses		592,399			687,356			670,103
Segment selling, general and administrative expenses
Oil and Gas		6,739			6,511			4,615
Air Medical		10,968			10,455			9,801
Technical Services		1,101			805			157
Total segment selling, general and administrative expenses		18,808			17,771			14,573
Total segment expenses		611,207			705,127			684,676
Net segment (loss) profit
Oil and Gas		(27,250	)		41,343			100,615
Air Medical		43,023			55,833			46,838
Technical Services		7,118			1,925			4,141
Total net segment profit		22,891			99,101			151,594
Other, net (2)		6,214			1,872			(10,539	)
Unallocated selling, general and administrative expenses		(25,610	)		(28,651	)		(28,597	)
Interest expense		(30,644	)		(29,066	)		(29,510	)
Loss on debt extinguishment		—			—			(29,833	)
(Loss) earnings before income taxes	$	(27,149	)	$	43,256		$	53,115

(1) Includes equity in gain/loss of unconsolidated affiliate.

(2) Includes gain/loss on disposition of property and equipment, asset impairments, and other income.

Summary of Gains on Disposition of Property and Equipment and Other Income

	Year Ended December 31,
	2016		2015		2014
	(Thousands of dollars)
Expenditures for Long-Lived Assets
Oil and Gas	$	59,278	$	32,501	$	119,235
Air Medical		22,429		22,685		37,317
Corporate		1,164		1,389		1,153
Total	$	82,871	$	56,575	$	157,705

	Year Ended December 31,
	2016		2015		2014
	(Thousands of dollars)
Depreciation and Amortization
Oil and Gas	$	40,170	$	42,709	$	29,635
Air Medical		19,716		18,177		13,067
Technical Services		564		518		493
Corporate		5,293		10,214		7,653
Total	$	65,743	$	71,618	$	50,848
Assets
Oil and Gas	$	674,788	$	704,472
Air Medical		368,474		329,484
Technical Services		9,568		7,345
Corporate		395,610		385,032
Total	$	1,448,440	$	1,426,333

Summary of Company's Revenues from External Customers and Long-Lived Assets, by Geographical Areas

The following table presents the Company’s revenues from external customers attributed to operations in the United States and foreign areas and long-lived assets in the United States and foreign areas.

	As of or for Year Ended December 31,
	2016		2015		2014
	(Thousands of dollars)
Operating Revenues:
United States	$	579,300	$	722,339	$	747,063
International		54,798		81,889		89,207
Total	$	634,098	$	804,228	$	836,270
Long-Lived Assets:
United States	$	751,290	$	773,939
International		152,687		109,590
Total	$	903,977	$	883,529