Operating Segments and Sales, Geographic and Credit Concentrations (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, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Revenues and Earnings (Loss) from Operations
External: Revenues									$ 750,592	$ 711,723	$ 519,385
Total revenues	197,179	198,899	159,404	195,110	207,680	168,230	154,214	181,599	750,592	711,723	519,385
External: Earnings (Loss) from Operations									150,907	121,420	32,749
Earnings from operations									150,907	121,420	32,749
Capital Expenditures									184,093	205,880	35,646
Depreciation & Amortization									27,712	24,810	22,866
Total Segment assets	825,609				809,758				825,609	809,758	703,770
Manufacturing [Member]
Segment Revenues and Earnings (Loss) from Operations
External: Revenues									646,100	633,547	453,092
Intersegment: Revenues									217,922	219,499	35,658
Total revenues									864,022	853,046	488,750
External: Earnings (Loss) from Operations									135,454	120,623	36,075
Intersegment: Earnings (Loss) from Operations									54,621	35,362	4,860
Earnings from operations									190,075	155,985	40,935
Capital Expenditures									12,168	16,856	2,743
Depreciation & Amortization									14,504	15,239	17,660
Total Segment assets	298,951				329,346				298,951	329,346	311,656
Railcar Leasing [Member]
Segment Revenues and Earnings (Loss) from Operations
External: Revenues									31,871	13,444	1,075
Total revenues									31,871	13,444	1,075
External: Earnings (Loss) from Operations									14,836	7,371	239
Intersegment: Earnings (Loss) from Operations									40	29	20
Earnings from operations									14,876	7,400	259
Capital Expenditures									162,068	185,918	29,444
Depreciation & Amortization									9,799	4,424	505
Total Segment assets	478,000				263,228				478,000	263,228	46,073
Railcar Services [Member]
Segment Revenues and Earnings (Loss) from Operations
External: Revenues									72,621	64,732	65,218
Intersegment: Revenues									233	495	285
Total revenues									72,854	65,227	65,503
External: Earnings (Loss) from Operations									14,372	10,718	12,476
Intersegment: Earnings (Loss) from Operations									(47)	(99)	19
Earnings from operations									14,325	10,619	12,495
Capital Expenditures									5,925	965	987
Depreciation & Amortization									2,506	2,903	2,851
Total Segment assets	52,150				49,060				52,150	49,060	47,408
Corporate [Member]
Segment Revenues and Earnings (Loss) from Operations
External: Earnings (Loss) from Operations									(13,755)	(17,292)	(16,041)
Earnings from operations									(13,755)	(17,292)	(16,041)
Capital Expenditures									3,932	2,141	2,472
Depreciation & Amortization									903	2,244	1,850
Eliminations [Member]
Segment Revenues and Earnings (Loss) from Operations
Intersegment: Revenues									(218,155)	(219,994)	(35,943)
Total revenues									(218,155)	(219,994)	(35,943)
Intersegment: Earnings (Loss) from Operations									(54,614)	(35,292)	(4,899)
Earnings from operations									(54,614)	(35,292)	(4,899)
Corporate And Eliminations [Member]
Segment Revenues and Earnings (Loss) from Operations
Total Segment assets	$ (3,492)				$ 168,124				$ (3,492)	$ 168,124	$ 298,633