Segment Reporting (Details) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2016 USD ($) segment	Mar. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Segment Reporting
Number of business segments \| segment			3
Segment revenue	$ 202,332	$ 179,725	$ 420,750	$ 379,322
Depreciation and amortization	(14,115)	(12,946)	(27,897)	(25,856)
Operating income (loss)	12,180	8,230	37,003	27,402
Net interest expense	(8,056)	(35,965)	(16,273)	(47,917)
Other income (expense), net	(12)	(33)	(81)	(302)
Income tax benefit (provision)	(1,500)	2,780	(5,100)	2,980
Income (loss) from continuing operations	2,612	(24,988)	15,549	(17,837)
Loss from discontinued operations, net of income taxes	(228)	(210)	(444)	(277)
Net income (loss)	2,384	(25,198)	15,105	(18,114)
Capital expenditures	13,197	8,703	20,882	17,474
Segment assets	970,654	979,019	970,654	979,019	$ 979,019
Building products
Segment Reporting
Segment revenue	129,195	106,406	261,040	223,940
Construction materials
Segment Reporting
Segment revenue	71,755	67,498	157,753	148,902
Energy technology
Segment Reporting
Segment revenue	1,382	5,821	1,957	6,480
Operating Segments \| Building products
Segment Reporting
Segment revenue	129,195	106,406	261,040	223,940
Depreciation and amortization	(9,691)	(8,702)	(19,157)	(17,415)
Operating income (loss)	10,820	4,679	25,905	16,627
Capital expenditures	11,144	6,131	17,148	12,152
Segment assets	461,565	412,867	461,565	412,867
Operating Segments \| Construction materials
Segment Reporting
Segment revenue	71,755	67,498	157,753	148,902
Depreciation and amortization	(3,949)	(3,799)	(7,783)	(7,535)
Operating income (loss)	9,215	8,175	26,168	21,663
Capital expenditures	1,197	1,026	1,976	2,374
Segment assets	311,693	294,057	311,693	294,057
Operating Segments \| Energy technology
Segment Reporting
Segment revenue	1,382	5,821	1,957	6,480
Depreciation and amortization	(324)	(341)	(647)	(694)
Operating income (loss)	(1,163)	1,473	(2,884)	(138)
Capital expenditures	0	61	0	229
Segment assets	39,529	45,671	39,529	45,671
Corporate, Non-Segment
Segment Reporting
Segment revenue	0	0	0	0
Depreciation and amortization	(151)	(104)	(310)	(212)
Operating income (loss)	(6,692)	(6,097)	(12,186)	(10,750)
Capital expenditures	856	1,485	1,758	2,719
Segment assets	$ 157,867	$ 226,424	$ 157,867	$ 226,424

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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