Operating Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 item	Sep. 30, 2013	Dec. 31, 2013
Operating segments
Number of operating segments			2
Revenue:
Lease rent revenue	$ 25,165	$ 25,779	$ 76,865	$ 75,016
Maintenance reserve revenue	13,066	8,891	41,657	29,908
Spare parts sales	1,854		2,470
Gain on sale of leased equipment	1,891	2,022	3,713	3,556
Other revenue	769	1,260	3,800	2,729
Total revenue	42,745	37,952	128,505	111,209
Expenses:
Depreciation and amortization expense	16,714	15,762	48,159	43,563
Cost of spare parts sales	1,444		1,953
General and administrative	9,107	6,792	28,055	24,265
Net finance costs	9,181	9,905	27,935	28,984
Other expense	4,305		10,671
Total expenses	40,751	41,275	116,773	113,503
Earnings (loss) from operations	1,994	(3,323)	11,732	(2,294)
Total assets	1,187,056		1,187,056		1,199,229
Operating Segments [Member] | Leasing and Related Operations Segment [Member]
Revenue:
Lease rent revenue	25,165		76,865
Maintenance reserve revenue	13,066		41,657
Gain on sale of leased equipment	1,891		3,713
Other revenue	673		2,908
Total revenue	40,795		125,143
Expenses:
Depreciation and amortization expense	16,643		47,943
General and administrative	8,405		26,072
Net finance costs	9,111		27,807
Other expense	4,305		10,671
Total expenses	38,464		112,493
Earnings (loss) from operations	2,331		12,650
Total assets	1,170,847		1,170,847		1,194,800
Operating Segments [Member] | Spare Parts Sales Segment [Member]
Revenue:
Spare parts sales	1,854		2,470
Other revenue	862		2,295
Total revenue	2,716		4,765
Expenses:
Depreciation and amortization expense	71		216
Cost of spare parts sales	1,444		1,953
General and administrative	702		1,983
Net finance costs	70		128
Total expenses	2,287		4,280
Earnings (loss) from operations	429		485
Total assets	16,209		16,209		4,429
Intersegment Eliminations [Member]
Revenue:
Other revenue	(766)		(1,403)
Total revenue	(766)		(1,403)
Expenses:
Earnings (loss) from operations	$ (766)		$ (1,403)