Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Revenue:
Lease rent revenue	$ 28,139	$ 25,097
Maintenance reserve revenue	15,819	14,148
Spare parts sales	2,609	2,151
Gain on sale of leased equipment	2,989	662
Other revenue	1,000	756
Total revenue	50,556	42,814
Expenses:
Depreciation and amortization expense	16,644	17,705
Cost Of Spare Parts and Equipment Sales	1,915	1,480
General and administrative	11,752	9,972
Net finance costs	10,008	8,416
Other expense	3,732	1,856
Total expenses	44,051	39,429
Interest expense	10,008	9,567
Earnings from operations	6,505	3,385
Total assets	1,277,460		$ 1,295,982
Operating Segments [Member] | Leasing and Related Operations
Revenue:
Lease rent revenue	28,139	25,097
Maintenance reserve revenue	15,819	14,148
Gain on sale of leased equipment	2,989	662
Other revenue	933	617
Total revenue	47,880	40,524
Expenses:
Depreciation and amortization expense	16,562	17,633
General and administrative	10,980	9,337
Net finance costs	9,913	8,326
Other expense	3,732	1,856
Total expenses	41,187	37,152
Earnings from operations	6,693	3,372
Total assets	1,252,992		1,269,396
Operating Segments [Member] | Spare Parts Sales
Revenue:
Spare parts sales	2,609	2,151
Other revenue	358	295
Total revenue	2,967	2,446
Expenses:
Depreciation and amortization expense	82	72
Cost Of Spare Parts and Equipment Sales	1,915	1,480
General and administrative	772	635
Net finance costs	95	90
Total expenses	2,864	2,277
Earnings from operations	103	169
Total assets	24,468		$ 26,586
Intersegment Eliminations [Member]
Revenue:
Other revenue	(291)	(156)
Total revenue	(291)	(156)
Expenses:
Earnings from operations	$ (291)	$ (156)