Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
REVENUE
Lease rent revenue													$ 130,369	$ 119,895	$ 108,046
Maintenance reserve revenue													80,189	57,091	53,396
Spare parts and equipment sales													51,423	17,783	25,582
Gain on sale of leased equipment													4,929	3,482	8,320
Other revenue													7,930	9,023	2,718
Total revenue	$ 63,189	$ 65,861	$ 67,844	$ 77,946	$ 55,476	$ 51,461	$ 49,618	$ 50,719	$ 55,186	$ 57,730	$ 43,810	$ 41,336	274,840	207,274	198,062
EXPENSES
Depreciation and amortization expense													66,023	66,280	69,424
Cost of spare parts and equipment sales													40,848	13,293	17,849
Write-down of equipment													24,930	9,514	9,181
General and administrative													55,737	47,780	42,744
Technical expense													9,729	6,993	9,403
Net finance costs:
Interest expense													48,720	41,144	39,012
Loss (gain) on debt extinguishment														(137)	1,151
Total net finance costs													48,720	41,281	37,861
Total expenses													245,987	185,141	186,462
Earnings from operations													28,853	22,133	11,600
Earnings from joint ventures													7,158	1,813	1,175
Income before income taxes													36,011	23,946	12,775
Income tax (benefit) expense													(26,147)	9,877	6,315
Net income													62,158	14,069	6,460
Preferred stock dividends													1,813	281
Accretion of preferred stock issuance costs													46	8
Net income attributable to common shareholders	$ 41,864	$ 4,939	$ 5,657	$ 7,839	$ 2,418	$ 3,985	$ 3,366	$ 4,011	$ 3,037	$ 2,551	$ (486)	$ 1,358	$ 60,299	$ 13,780	$ 6,460
Basic earnings per common share: (in dollars per share)	$ 6.87	$ 0.82	$ 0.94	$ 1.28	$ 0.40	$ 0.63	$ 0.50	$ 0.57	$ 0.39	$ 0.33	$ (0.06)	$ 0.17	$ 9.93	$ 2.10	$ 0.83
Diluted earnings per common share: (in dollars per share)	$ 6.75	$ 0.80	$ 0.92	$ 1.25	$ 0.39	$ 0.62	$ 0.49	$ 0.55	$ 0.38	$ 0.32	$ (0.06)	$ 0.17	$ 9.69	$ 2.05	$ 0.81
Basic weighted average common shares outstanding	6,090	6,055	6,036	6,114	6,149	6,307	6,685	7,149	7,739	7,839	7,841	7,848	6,074	6,570	7,817
Diluted average common shares outstanding (in shares)	6,201	6,173	6,142	6,240	6,275	6,448	6,819	7,272	7,872	7,963	7,841	8,044	6,220	6,714	7,987