Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 Aircraft Segment Location States	Mar. 31, 2016
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	3
National Science Foundation [Member]
Segment Reporting Information [Line Items]
Number of aircraft assigned	6
Hospitals Contracts [Member]
Segment Reporting Information [Line Items]
Segment revenue	19.00%	31.00%
Fixed Term Customer Contract [Member]
Segment Reporting Information [Line Items]
Segment revenue	90.00%	93.00%
Contracted Customers [Member]
Segment Reporting Information [Line Items]
Segment revenue	10.00%	7.00%
Minimum [Member]
Segment Reporting Information [Line Items]
Term of contract	1 year
Maximum [Member]
Segment Reporting Information [Line Items]
Term of contract	7 years
Oil and Gas [Member]
Segment Reporting Information [Line Items]
Number of aircraft available for use	131
Segment revenue	53.00%	54.00%
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	6.00%	3.00%
Air Medical [Member]
Segment Reporting Information [Line Items]
Segment revenue	41.00%	43.00%
Number of aircraft assigned	104
Number of states in which company operates aircrafts | States	18
Locations in which company operates Aircrafts | Location	72