Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 segment	Mar. 31, 2013	Sep. 30, 2013
Segment Reporting
Number of business segments			3
Segment reporting
Segment revenue	$ 156,512	$ 140,988	$ 322,127	$ 290,561
Depreciation and amortization	(13,413)	(13,146)	(26,460)	(25,582)
Operating income (loss)	549	(1,116)	8,109	4,916
Net interest expense	(12,234)	(11,139)	(22,290)	(21,611)
Other income (expense), net	(32)	202	(20)	238
Income tax benefit	2,210	1,770	2,560	2,300
Loss from continuing operations	(9,507)	(10,283)	(11,641)	(14,157)
Loss from discontinued operations, net of income taxes	(575)	2,023	125	25
Net loss	(10,082)	(8,260)	(11,516)	(14,132)
Capital expenditures	9,056	7,854	15,944	14,407
Segment assets	855,198	724,009	855,198	724,009	724,009
Operating Segments | Light Building Products
Segment reporting
Segment revenue	94,139	84,778	187,151	161,466
Depreciation and amortization	(9,546)	(9,418)	(18,758)	(18,093)
Operating income (loss)	1,907	1,335	6,993	4,462
Capital expenditures	6,864	5,846	11,316	10,891
Segment assets	371,456	306,686	371,456	306,686
Operating Segments | Heavy Construction Materials
Segment reporting
Segment revenue	59,093	54,014	130,614	122,172
Depreciation and amortization	(3,319)	(3,131)	(6,605)	(6,271)
Operating income (loss)	5,228	3,666	15,161	11,273
Capital expenditures	1,377	1,377	2,562	2,060
Segment assets	354,677	358,684	354,677	358,684
Operating Segments | Energy Technology
Segment reporting
Segment revenue	3,280	2,196	4,362	6,923
Depreciation and amortization	(479)	(519)	(967)	(1,085)
Operating income (loss)	(821)	(1,205)	(3,107)	(1,123)
Capital expenditures	75	117	305	269
Segment assets	32,286	34,509	32,286	34,509
Corporate
Segment reporting
Segment revenue	0	0	0	0
Depreciation and amortization	(69)	(78)	(130)	(133)
Operating income (loss)	(5,765)	(4,912)	(10,938)	(9,696)
Capital expenditures	740	514	1,761	1,187
Segment assets	$ 96,779	$ 24,130	$ 96,779	$ 24,130