Operating Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2013 item	Dec. 31, 2012	Dec. 31, 2011
Operating Segments
Number of operating segments													2
Revenue:
Lease rent revenue													$ 101,737	$ 94,591	$ 104,663
Maintenance reserve revenue													46,694	41,387	39,161
Spare parts sales													88
Gain on sale of leased equipment													5,675	5,499	11,110
Other revenue													4,306	6,613	1,719
Total revenue	47,203	37,952	37,953	35,304	39,692	37,506	35,153	35,739	37,669	39,480	38,692	40,812	158,412	148,090	156,653
Expenses:
Depreciation and amortization expense													58,727	52,591	51,250
General and administrative													33,868	34,551	35,701
Interest expense													38,719	31,749	35,201
Other expense													19,324
Total expenses													150,638	147,153	134,063
Earnings from operations													7,774	937	22,590
Total assets	1,199,229				1,078,715								1,199,229	1,078,715
Leasing and Related Operations
Revenue:
Lease rent revenue													101,737
Maintenance reserve revenue													46,694
Gain on sale of leased equipment													5,675
Other revenue													3,365
Total revenue													157,471
Expenses:
Depreciation and amortization expense													58,684
General and administrative													33,490
Interest expense													38,719
Other expense													19,312
Total expenses													150,205
Earnings from operations													7,266
Total assets	1,194,800												1,194,800
Spare Parts Sales
Revenue:
Spare parts sales													88
Other revenue													853
Total revenue													941
Expenses:
Depreciation and amortization expense													43
General and administrative													378
Other expense													12
Total expenses													433
Earnings from operations													508
Total assets	$ 4,429												$ 4,429