Segment Information (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012	Jun. 30, 2013 Segment ft		Jun. 30, 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	52,987,000		39,725,000	103,946,000		79,132,000
Total operating expenses	25,144,000		15,363,000	48,255,000		31,878,000
Operating income	27,843,000		24,362,000	55,691,000		47,254,000
Net interest expense	8,954,000		6,318,000	18,463,000		12,249,000
Net income before income taxes and non-controlling interest	18,889,000		18,044,000	37,228,000		35,005,000
Total assets	1,615,982,000	[1]	1,171,957,000	1,615,982,000	[1]	1,171,957,000	1,387,941,000	[1]
Geographic Data [Abstract]
Net book value	1,657,000			1,657,000			1,847,000
Railcar Equipment [Member]
Geographic Data [Abstract]
Net book value	53,400,000			53,400,000
Equipment Leasing [Member]
Segment Reporting Information [Line Items]
Total revenue	50,693,000		36,719,000	99,422,000		70,669,000
Total operating expenses	23,799,000		13,394,000	45,532,000		27,714,000
Operating income	26,894,000		23,325,000	53,890,000		42,955,000
Net interest expense	8,955,000		6,320,000	18,467,000		12,256,000
Net income before income taxes and non-controlling interest	17,939,000		17,005,000	35,423,000		30,699,000
Total assets	1,606,728,000		1,149,676,000	1,606,728,000		1,149,676,000
Equipment Management [Member]
Segment Reporting Information [Line Items]
Total revenue	2,294,000		3,006,000	4,524,000		8,463,000
Total operating expenses	1,345,000		1,969,000	2,723,000		4,164,000
Operating income	949,000		1,037,000	1,801,000		4,299,000
Net interest expense	0		0	0		0
Net income before income taxes and non-controlling interest	949,000		1,037,000	1,801,000		4,299,000
Total assets	9,254,000		22,281,000	9,254,000		22,281,000
Unallocated [Member]
Segment Reporting Information [Line Items]
Total revenue	0		0	0		0
Total operating expenses	0		0	0		0
Operating income	0		0	0		0
Net interest expense	(1,000)		(2,000)	(4,000)		(7,000)
Net income before income taxes and non-controlling interest	1,000		2,000	4,000		7,000
Total assets	$ 0		$ 0	$ 0		$ 0

[1] Total assets at June 30, 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, $10,198 and $3,695; Net investment in direct finance leases, $96 and $0; and Rental equipment net of accumulated depreciation, $78,626 and $62,286, respectively.