SCHEDULE I - Parent Company Information - Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	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, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
REVENUE
Lease rent revenue													$ 119,895	$ 108,046	$ 101,431
Maintenance reserve revenue													57,091	53,396	53,322
Spare parts and equipment sales													17,783	25,582	8,917
Gain on sale of leased equipment													3,482	8,320	5,882
Other revenue													9,023	2,718	4,506
Total revenue	$ 55,476	$ 51,461	$ 49,618	$ 50,719	$ 55,186	$ 57,730	$ 43,810	$ 41,336	$ 41,205	$ 45,519	$ 43,994	$ 43,340	207,274	198,062	174,058
EXPENSES
Cost Of Spare Parts and Equipment Sales													13,293	17,849	7,474
Write-down of equipment													9,514	9,181	5,602
General and administrative													47,780	42,744	35,859
Technical expense													6,993	9,403	12,336
Net finance costs:
Interest expense													41,144	39,012	37,062
Total net finance costs													41,281	37,861	37,062
Total expenses													185,141	186,462	163,647
Earnings from operations													22,133	11,600	10,411
Earnings from joint ventures													1,813	1,175	1,329
Income before income taxes													23,946	12,775	11,740
Income tax (expense) benefit													(9,877)	(6,315)	(4,560)
Net income													14,069	6,460	7,180
Preferred stock dividends													281
Accretion of preferred stock issuance costs													8
Net income attributable to common shareholders	$ 2,418	$ 3,985	$ 3,366	$ 4,011	$ 3,037	$ 2,551	$ (486)	$ 1,358	$ (491)	$ 1,000	$ 2,319	$ 4,352	13,780	6,460	7,180
Parent Company
REVENUE
Lease rent revenue													76,283	63,443	50,492
Maintenance reserve revenue													30,742	29,937	22,229
Spare parts and equipment sales													8,404	20,210	7,588
Gain on sale of leased equipment													3,322	2,420	2,276
Other revenue													10,660	7,017	5,227
Total revenue													129,411	123,027	87,812
EXPENSES
Depreciation expense													43,451	40,623	29,276
Cost Of Spare Parts and Equipment Sales													6,591	13,559	6,354
Write-down of equipment													5,989	6,764	4,681
General and administrative													39,201	35,898	29,479
Technical expense													4,637	6,805	4,455
Net finance costs:
Interest expense													23,358	18,448	13,500
Total expenses													123,227	122,097	87,745
Earnings from operations													6,184	930	67
Earnings from joint ventures													1,813	1,175	1,329
Income before income taxes													7,997	2,105	1,396
Income tax (expense) benefit													4,710	2,277	1,346
Equity in income of subsidiaries, net of tax of $199, $3,357, and $8,749 at December 31, 2013, 2012 and 2011, respectively													10,782	6,632	7,130
Net income													14,069	6,460	7,180
Preferred stock dividends													281
Accretion of preferred stock issuance costs													8
Net income attributable to common shareholders													$ 13,780	$ 6,460	$ 7,180