Operating Segment and Sales and Credit Concentrations (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment			3
Total revenues	$ 150,484	$ 191,998	$ 326,664	$ 455,774
Earnings from operations	35,974	55,264	76,671	115,279
Total Assets	1,432,600		1,432,600		$ 1,525,074
Corporate/Eliminations [Member]
Segment Reporting Information [Line Items]
Total Assets	(86,069)		(86,069)		5,293
Manufacturing [Member]
Segment Reporting Information [Line Items]
Total revenues	106,814	268,174	254,237	573,716
Earnings from operations	15,538	69,941	38,224	140,379
Total Assets	260,088		260,088		272,721
Railcar Leasing [Member]
Segment Reporting Information [Line Items]
Total revenues	33,209	28,216	65,977	52,801
Earnings from operations	20,237	16,976	39,912	31,740
Total Assets	1,199,291		1,199,291		1,190,180
Railcar Services [Member]
Segment Reporting Information [Line Items]
Total revenues	20,336	19,395	40,915	36,877
Earnings from operations	3,059	3,880	6,567	6,747
Total Assets	59,290		59,290		$ 56,880
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Earnings from operations	(4,441)	(2,463)	(8,949)	(6,813)
Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	(9,875)	(123,787)	(34,465)	(207,620)
Earnings from operations	1,581	(33,070)	917	(56,774)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	150,484	191,998	326,664	455,774
Operating Segments [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Total revenues	97,548	144,481	221,340	366,292
Operating Segments [Member] | Railcar Leasing [Member]
Segment Reporting Information [Line Items]
Total revenues	33,209	28,216	65,977	52,801
Operating Segments [Member] | Railcar Services [Member]
Segment Reporting Information [Line Items]
Total revenues	19,727	19,301	39,347	36,681
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Intersegment Eliminations [Member] | Manufacturing [Member]
Segment Reporting Information [Line Items]
Total revenues	9,266	123,693	32,897	207,424
Intersegment Eliminations [Member] | Railcar Leasing [Member]
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Intersegment Eliminations [Member] | Railcar Services [Member]
Segment Reporting Information [Line Items]
Total revenues	609	94	1,568	196
Intersegment Eliminations [Member] | Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	$ (9,875)	$ (123,787)	$ (34,465)	$ (207,620)