Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 segment	Mar. 31, 2012	Sep. 30, 2012
Segment Reporting
Number of business segments			3
Segment reporting
Segment revenue	$ 140,988	$ 129,632	$ 290,561	$ 267,059
Depreciation and amortization	(13,146)	(13,014)	(25,582)	(26,196)
Operating income (loss)	(1,116)	(1,798)	4,916	2,615
Net interest expense	(11,139)	(13,527)	(21,611)	(25,983)
Other income (expense), net	202	(173)	238	(4,310)
Income tax benefit (provision)	1,770	(2,730)	2,300	(3,830)
Loss from continuing operations	(10,283)	(18,228)	(14,157)	(31,508)
(Income) Loss from discontinued operations, net of income taxes	2,023	(2,330)	25	(12,798)
Net loss	(8,260)	(20,558)	(14,132)	(44,306)
Capital expenditures	7,854	5,213	14,407	11,832
Segment assets	696,437	659,923	696,437	659,923	680,937
Light Building Products
Segment reporting
Segment revenue	84,778	74,311	161,466	147,645
Depreciation and amortization	(9,418)	(8,908)	(18,093)	(17,972)
Operating income (loss)	1,335	2,108	4,462	2,881
Capital expenditures	5,846	4,272	10,891	8,873
Segment assets	304,711	273,122	304,711	273,122
Heavy Construction Materials
Segment reporting
Segment revenue	54,014	51,239	122,172	114,377
Depreciation and amortization	(3,131)	(3,493)	(6,271)	(7,024)
Operating income (loss)	3,666	2,870	11,273	11,624
Capital expenditures	1,377	640	2,060	1,424
Segment assets	278,115	295,323	278,115	295,323
Energy Technology
Segment reporting
Segment revenue	2,196	4,082	6,923	5,037
Depreciation and amortization	(519)	(572)	(1,085)	(1,144)
Operating income (loss)	(1,205)	(706)	(1,123)	(2,707)
Capital expenditures	117	112	269	1,328
Segment assets	66,697	46,868	66,697	46,868
Corporate
Segment reporting
Segment revenue	0	0	0	0
Depreciation and amortization	(78)	(41)	(133)	(56)
Operating income (loss)	(4,912)	(6,070)	(9,696)	(9,183)
Capital expenditures	514	189	1,187	207
Segment assets	$ 46,914	$ 44,610	$ 46,914	$ 44,610