Segment Information - Additional Information (Detail) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016 USD ($) Employees Pilot	Sep. 30, 2015	Sep. 30, 2016 Aircraft Segment Location States Entity	Sep. 30, 2015
Segment Reporting Information [Line Items]
Number of reportable segments | Segment				3
Hospitals Contracts [Member]
Segment Reporting Information [Line Items]
Segment revenue	27.00%		34.00%	29.00%	37.00%
Voluntary Employee Retirement Package [Member]
Segment Reporting Information [Line Items]
Qualifying age				64 years
Number of employees accepted VERP | Employees		15
Severance costs | $		$ 1.6
Voluntary Furlough Program to Oil and Gas Pilots [Member]
Segment Reporting Information [Line Items]
Severance costs | $		$ 0.4
Number of employees accepted furlough program | Pilot		26
Guaranteed period to recall under program		12 months
Oil and Gas [Member]
Segment Reporting Information [Line Items]
Number of aircraft available for use				139
Segment revenue	49.00%		56.00%	51.00%	57.00%
Oil and Gas [Member] | Minimum [Member] | Major Customer [Member]
Segment Reporting Information [Line Items]
Working period with major customers				30 years
Oil and Gas [Member] | Minimum [Member] | ENI Petroleum [Member]
Segment Reporting Information [Line Items]
Working period with major customers				15 years
Technical Services [Member]
Segment Reporting Information [Line Items]
Segment revenue	4.00%		4.00%	4.00%	4.00%
Air Medical [Member]
Segment Reporting Information [Line Items]
Segment revenue	47.00%		40.00%	45.00%	37.00%
Number of aircraft assigned				104
Number of aircraft operated				97
Number of states in which company operates aircrafts | States				18
Locations in which company operates Aircrafts | Location				72
Fixed revenue streams | Entity				0
Air Medical [Member] | Middle East [Member]
Segment Reporting Information [Line Items]
Number of aircraft operated				8
Locations in which company operates Aircrafts | Location				3
Number of revenue generating aircrafts				4