Operating Segments (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Operating segments
Number of operating segments | segment			2
Revenue:
Lease rent revenue	$ 33,474	$ 31,270	$ 95,045	$ 88,727
Maintenance reserve revenue	20,370	14,229	64,212	45,562
Spare parts and equipment sales	9,294	4,160	41,273	10,465
Gain on sale of leased equipment	174	180	4,684	3,430
Other revenue	2,549	1,622	6,439	3,614
Total revenue	65,861	51,461	211,653	151,798
Expenses:
Depreciation and amortization expense	16,142	16,628	48,786	49,235
Cost of spare parts and equipment sales	6,416	3,066	29,546	7,785
Write-down of equipment	6,958	1,995	22,243	5,924
General and administrative	14,308	12,257	40,574	34,694
Technical expense	2,605	1,414	7,345	4,913
Net finance costs	14,220	10,230	36,398	30,772
Other expense		3,409		10,837
Total expenses	60,649	45,590	184,892	133,323
Earnings from operations	5,212	5,871	26,761	18,475
Total assets	1,435,899		1,435,899		$ 1,337,887
Operating Segments [Member] | Leasing and Related Operations
Revenue:
Lease rent revenue	33,474	31,270	95,045	88,727
Maintenance reserve revenue	20,370	14,229	64,212	45,562
Spare parts and equipment sales		900	19,300	1,800
Gain on sale of leased equipment	174	180	4,684	3,430
Other revenue	2,538	1,487	6,314	3,392
Total revenue	56,556	48,066	189,555	142,911
Expenses:
Depreciation and amortization expense	16,056	16,541	48,526	48,981
Cost of spare parts and equipment sales		640	14,623	1,288
Write-down of equipment	6,226		19,668
General and administrative	13,387	11,500	38,008	32,438
Technical expense	2,605		7,345
Net finance costs	14,220	10,116	36,398	30,443
Other expense		2,934		10,362
Total expenses	52,494	41,731	164,568	123,512
Earnings from operations	4,062	6,335	24,987	19,399
Total assets	1,417,166		1,417,166		1,307,460
Operating Segments [Member] | Spare Parts Sales
Revenue:
Spare parts and equipment sales	9,294	3,260	21,973	8,665
Other revenue	247	786	697	1,734
Total revenue	9,541	4,046	22,670	10,399
Expenses:
Depreciation and amortization expense	86	87	260	254
Cost of spare parts and equipment sales	6,416	2,426	14,923	6,497
Write-down of equipment	732		2,575
General and administrative	921	757	2,566	2,256
Net finance costs		114		329
Other expense		475		475
Total expenses	8,155	3,859	20,324	9,811
Earnings from operations	1,386	187	2,346	588
Total assets	18,733		18,733		$ 30,427
Intersegment Eliminations [Member]
Revenue:
Other revenue	(236)	(651)	(572)	(1,512)
Total revenue	(236)	(651)	(572)	(1,512)
Expenses:
Earnings from operations	$ (236)	$ (651)	$ (572)	$ (1,512)