Condensed Consolidating Financial Information (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Revenue:
Light building products	$ 84,778	$ 74,311	$ 161,466	$ 147,645
Heavy construction materials	54,014	51,239	122,172	114,377
Energy technology	2,196	4,082	6,923	5,037
Total revenue	140,988	129,632	290,561	267,059
Cost of revenue:
Light building products	64,126	54,613	120,627	109,943
Heavy construction materials	43,396	41,380	96,980	88,478
Energy technology	1,055	2,074	3,298	2,631
Total cost of revenue	108,577	98,067	220,905	201,052
Gross profit	32,411	31,565	69,656	66,007
Operating expenses:
Amortization	5,288	5,298	10,224	10,803
Research and development	1,817	1,616	3,423	3,470
Selling, general and administrative	26,422	25,692	51,093	46,974
Restructuring costs	0	757	0	2,145
Total operating expenses	33,527	33,363	64,740	63,392
Operating income (loss)	(1,116)	(1,798)	4,916	2,615
Other income (expense):
Net interest expense	(11,139)	(13,527)	(21,611)	(25,983)
Other, net	202	(173)	238	(4,310)
Total other income (expense), net	(10,937)	(13,700)	(21,373)	(30,293)
Income (loss) from continuing operations before income taxes	(12,053)	(15,498)	(16,457)	(27,678)
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)
Guarantor Subsidiaries
Revenue:
Light building products	84,778	74,311	161,466	147,645
Heavy construction materials	54,014	51,239	122,172	114,377
Energy technology	2,196	4,082	6,923	5,037
Total revenue	140,988	129,632	290,561	267,059
Cost of revenue:
Light building products	64,126	54,613	120,627	109,943
Heavy construction materials	43,396	41,380	96,980	88,478
Energy technology	1,055	2,074	3,298	2,631
Total cost of revenue	108,577	98,067	220,905	201,052
Gross profit	32,411	31,565	69,656	66,007
Operating expenses:
Amortization	5,288	5,298	10,224	10,803
Research and development	1,817	1,616	3,423	3,470
Selling, general and administrative	21,510	19,622	41,397	37,791
Restructuring costs		757		2,145
Total operating expenses	28,615	27,293	55,044	54,209
Operating income (loss)	3,796	4,272	14,612	11,798
Other income (expense):
Net interest expense	(44)	(18)	(58)	(37)
Other, net	167	(173)	203	(6,335)
Total other income (expense), net	123	(191)	145	(6,372)
Income (loss) from continuing operations before income taxes	3,919	4,081	14,757	5,426
Income tax benefit (provision)	(770)	678	(2,070)	867
Loss from continuing operations	3,149	4,759	12,687	6,293
Income (loss) from discontinued operations, net of income taxes	2,023	(2,330)	25	(12,798)
Net loss	5,172	2,429	12,712	(6,505)
Parent Company
Operating expenses:
Selling, general and administrative	4,912	6,070	9,696	9,183
Total operating expenses	4,912	6,070	9,696	9,183
Operating income (loss)	(4,912)	(6,070)	(9,696)	(9,183)
Other income (expense):
Net interest expense	(11,095)	(13,509)	(21,553)	(25,946)
Other, net	35		35	2,025
Total other income (expense), net	(11,060)	(13,509)	(21,518)	(23,921)
Income (loss) from continuing operations before income taxes	(15,972)	(19,579)	(31,214)	(33,104)
Income tax benefit (provision)	2,540	(3,408)	4,370	(4,697)
Loss from continuing operations	(13,432)	(22,987)	(26,844)	(37,801)
Net loss	$ (13,432)	$ (22,987)	$ (26,844)	$ (37,801)