Operating Segments and Sales, Geographic and Credit Concentrations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Revenues and Earnings (Loss) from Operations
Total revenues	$ 260,895	$ 172,667	$ 191,998	$ 263,776	$ 150,540	$ 162,842	$ 237,509	$ 182,115	$ 889,336	$ 733,006	$ 750,592
Earnings from operations									226,706	170,058	150,907
Payments to Acquire Productive Assets									248,260	327,750	184,093
Depreciation & Amortization									45,729	34,212	27,712
Total Segment assets	1,530,155				1,192,409				1,530,155	1,192,409	825,609
Manufacturing [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									1,019,460	1,019,621	864,022
Earnings from operations									240,891	262,937	190,075
Payments to Acquire Productive Assets									21,589	13,298	12,168
Depreciation & Amortization									15,024	14,472	14,504
Total Segment assets	272,721				318,157				272,721	318,157	264,689
Railcar Leasing [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									116,714	65,108	31,871
Earnings from operations									70,319	36,090	14,876
Payments to Acquire Productive Assets									211,646	307,820	162,068
Depreciation & Amortization									26,163	16,454	9,799
Total Segment assets	1,195,261				908,010				1,195,261	908,010	478,000
Railcar Services [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									74,497	67,842	72,854
Earnings from operations									13,898	10,366	14,325
Payments to Acquire Productive Assets									8,865	4,672	5,925
Depreciation & Amortization									2,818	2,609	2,506
Total Segment assets	$ 56,880				$ 52,639				56,880	52,639	52,150
Corporate [Member]
Segment Revenues and Earnings (Loss) from Operations
Earnings from operations									(18,779)	(18,339)	(17,085)
Payments to Acquire Productive Assets									6,160	1,960	3,932
Depreciation & Amortization									1,724	677	903
Eliminations [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									(321,335)	(419,565)	(218,155)
Earnings from operations									(79,623)	(120,996)	(51,284)
Operating Segments [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									889,336	733,006	750,592
Operating Segments [Member] | Manufacturing [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									700,061	600,326	646,100
Operating Segments [Member] | Railcar Leasing [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									116,714	65,108	31,871
Operating Segments [Member] | Railcar Services [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									72,561	67,572	72,621
Eliminations [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									0	0	0
Eliminations [Member] | Manufacturing [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									319,399	419,295	217,922
Eliminations [Member] | Railcar Leasing [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									0	0	0
Eliminations [Member] | Railcar Services [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									1,936	270	233
Eliminations [Member] | Eliminations [Member]
Segment Revenues and Earnings (Loss) from Operations
Total revenues									$ (321,335)	$ (419,565)	$ (218,155)
Foreign Operations [Member]
Segment Reporting Information [Line Items]
Sales Revenue Net Percentage									4.90%	4.20%	2.00%