Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	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, 2012	Dec. 31, 2011	Dec. 31, 2010
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]
Rental revenue									152,982	106,694	64,892
Management fee revenue									12,094	12,957	10,348
Gain on sale of container portfolios									1,256	2,345	614
Finance lease income									7,593	3,710	2,045
Total revenue	49,854	44,939	39,725	39,407	36,243	32,962	28,759	27,742	173,925	125,706	77,899
Depreciation of rental equipment									48,352	33,633	20,807
Amortization of intangible assets									902	1,254	1,377
Gain on disposition of used rental equipment									(12,445)	(13,374)	(9,112)
Storage, handling and other expenses									9,402	5,513	6,170
Marketing, general and administrative expense									24,658	21,009	21,218
Loss (gain) on foreign exchange									170	(354)	513
Total Operating expenses	20,268	18,893	15,363	16,515	15,342	11,274	11,839	9,226	71,039	47,681	40,973
Operating income	29,586	26,046	24,362	22,892	20,901	21,688	16,920	18,516	102,886	78,025	36,926
Interest expense									28,796	16,139	5,278
Interest income									(9)	(12)	(109)
Net interest expense									28,787	16,127	5,169
Net income before income taxes and non-controlling interest									74,099	61,898	31,757
Total assets	1,387,941				953,368				1,387,941	953,368
Geographic Data [Abstract]
Net book value	1,847				2,095				1,847	2,095
Railcar Equipment [Member]
Geographic Data [Abstract]
Net book value	52,800								52,800
Equipment Leasing [Member]
Segment Reporting Information [Line Items]
Rental revenue									152,982	106,694	64,892
Management fee revenue									0	0	0
Gain on sale of container portfolios									0	0	0
Finance lease income									7,593	3,710	2,045
Total revenue									160,575	110,404	66,937
Depreciation of rental equipment									48,352	33,633	20,807
Amortization of intangible assets									487	625	752
Gain on disposition of used rental equipment									(12,445)	(13,374)	(9,112)
Storage, handling and other expenses									9,402	5,513	6,170
Marketing, general and administrative expense									18,320	14,412	15,807
Loss (gain) on foreign exchange									170	(354)	513
Total Operating expenses									64,286	40,455	34,937
Operating income									96,289	69,949	32,000
Interest expense									28,796	16,139	5,278
Interest income									0	0	0
Net interest expense									28,796	16,139	5,278
Net income before income taxes and non-controlling interest									67,493	53,810	26,722
Total assets	1,368,236				933,094				1,368,236	933,094
Container Management [Member]
Segment Reporting Information [Line Items]
Rental revenue									0	0	0
Management fee revenue									12,094	12,957	10,348
Gain on sale of container portfolios									1,256	2,345	614
Finance lease income									0	0	0
Total revenue									13,350	15,302	10,962
Depreciation of rental equipment									0	0	0
Amortization of intangible assets									415	629	625
Gain on disposition of used rental equipment									0	0	0
Storage, handling and other expenses									0	0	0
Marketing, general and administrative expense									6,338	6,597	5,411
Loss (gain) on foreign exchange									0	0	0
Total Operating expenses									6,753	7,226	6,036
Operating income									6,597	8,076	4,926
Interest expense									0	0	0
Interest income									0	0	0
Net interest expense									0	0	0
Net income before income taxes and non-controlling interest									6,597	8,076	4,926
Total assets	19,705				20,274				19,705	20,274
Unallocated [Member]
Segment Reporting Information [Line Items]
Rental revenue									0	0	0
Management fee revenue									0	0	0
Gain on sale of container portfolios									0	0	0
Finance lease income									0	0	0
Total revenue									0	0	0
Depreciation of rental equipment									0	0	0
Amortization of intangible assets									0	0	0
Gain on disposition of used rental equipment									0	0	0
Storage, handling and other expenses									0	0	0
Marketing, general and administrative expense									0	0	0
Loss (gain) on foreign exchange									0	0	0
Total Operating expenses									0	0	0
Operating income									0	0	0
Interest expense									0	0	0
Interest income									(9)	(12)	(109)
Net interest expense									(9)	(12)	(109)
Net income before income taxes and non-controlling interest									9	12	109
Total assets	$ 0				$ 0				$ 0	$ 0