Operating Segment and Sales and Credit Concentrations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 segment	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of Reportable Segments			3
External: Revenues	$ 159,404	$ 154,214	$ 354,514	$ 335,813
Intersegment: Revenues	0	0	0	0
Total revenues	159,404	154,214	354,514	335,813
External: Earnings (Loss) from Operations	39,869	25,960	71,098	49,765
Intersegment: Earnings (Loss) from Operations	0	0	0	0
Earnings from operations	39,869	25,960	71,098	49,765
Total Assets	758,673		758,673		809,758
Manufacturing [Member]
Segment Reporting Information [Line Items]
External: Revenues	132,242	134,748	305,217	299,061
Intersegment: Revenues	45,083	84,540	100,491	132,089
Total revenues	177,325	219,288	405,708	431,150
External: Earnings (Loss) from Operations	32,780	26,334	66,759	51,486
Intersegment: Earnings (Loss) from Operations	10,126	14,346	19,908	23,268
Earnings from operations	42,906	40,680	86,667	74,754
Total Assets	318,352		318,352		329,346
Railcar Leasing [Member]
Segment Reporting Information [Line Items]
External: Revenues	7,527	2,668	14,070	4,048
Intersegment: Revenues	0	0	0	0
Total revenues	7,527	2,668	14,070	4,048
External: Earnings (Loss) from Operations	3,645	1,021	5,808	1,617
Intersegment: Earnings (Loss) from Operations	8	7	12	13
Earnings from operations	3,653	1,028	5,820	1,630
Total Assets	362,352		362,352		263,228
Railcar Services [Member]
Segment Reporting Information [Line Items]
External: Revenues	19,635	16,798	35,227	32,704
Intersegment: Revenues	46	191	95	220
Total revenues	19,681	16,989	35,322	32,924
External: Earnings (Loss) from Operations	4,083	3,396	6,388	5,739
Intersegment: Earnings (Loss) from Operations	(41)	(44)	2	(50)
Earnings from operations	4,042	3,352	6,390	5,689
Total Assets	46,163		46,163		49,060
Corporate and Eliminations [Member]
Segment Reporting Information [Line Items]
External: Revenues	0	0	0	0
Intersegment: Revenues	(45,129)	(84,731)	(100,586)	(132,309)
Total revenues	(45,129)	(84,731)	(100,586)	(132,309)
External: Earnings (Loss) from Operations	(639)	(4,791)	(7,857)	(9,077)
Intersegment: Earnings (Loss) from Operations	(10,093)	(14,309)	(19,922)	(23,231)
Earnings from operations	(10,732)	(19,100)	(27,779)	(32,308)
Total Assets	$ 31,806		$ 31,806		$ 168,124