Segment Information (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 ft Segment		Mar. 31, 2012	Dec. 31, 2012
Segment Information [Abstract]
Number of operating industry segments	1
Number of reportable segments	2
Inter-segment revenues	$ 0
Size of containers (in foots)	20
Segment Reporting Information [Line Items]
Total revenue	50,959,000		39,407,000
Total operating expenses	23,111,000		16,515,000
Operating income	27,848,000		22,892,000
Net interest expense	9,509,000		5,931,000
Net income before income taxes and non-controlling interest	18,339,000		16,961,000
Total assets	1,535,680,000	[1]	1,014,740,000	1,387,941,000	[1]
Geographic Data [Abstract]
Net book value	1,786,000			1,847,000
Railcar Equipment [Member]
Geographic Data [Abstract]
Net book value	52,500,000
Equipment Leasing [Member]
Segment Reporting Information [Line Items]
Total revenue	48,729,000		33,950,000
Total operating expenses	21,734,000		14,320,000
Operating income	26,995,000		19,630,000
Net interest expense	9,512,000		5,936,000
Net income before income taxes and non-controlling interest	17,483,000		13,694,000
Total assets	1,522,856,000		994,743,000
Equipment Management [Member]
Segment Reporting Information [Line Items]
Total revenue	2,230,000		5,457,000
Total operating expenses	1,377,000		2,195,000
Operating income	853,000		3,262,000
Net interest expense	0		0
Net income before income taxes and non-controlling interest	853,000		3,262,000
Total assets	12,824,000		19,997,000
Unallocated [Member]
Segment Reporting Information [Line Items]
Total revenue	0		0
Total operating expenses	0		0
Operating income	0		0
Net interest expense	(3,000)		(5,000)
Net income before income taxes and non-controlling interest	3,000		5,000
Total assets	$ 0		$ 0

[1] Total assets at March 31, 2013 and December 31, 2012, include the following assets of certain variable interest entities (VIEs) that can only be used to settle the liabilities of those VIEs: Cash, $6,441 and $3,695; and Rental equipment net of accumulated depreciation, $79,402 and $62,286, respectively.