Segment Reporting (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Sep. 30, 2016 USD ($)
Segment Reporting
Number of business segments | segment	3
Segment revenue	$ 255,575	$ 218,418
Depreciation and amortization	(17,842)	(13,782)
Operating income (loss)	19,340	24,823
Net interest expense	(8,919)	(8,217)
Other income (expense), net	154	(69)
Income tax provision	(3,900)	(3,600)
Income from continuing operations	6,675	12,937
Income (loss) from discontinued operations, net of income taxes	153	(216)
Net income	6,828	12,721
Capital expenditures	15,540	7,685
Segment assets	1,220,195	1,238,443	$ 1,238,443
Building products
Segment Reporting
Segment revenue	135,041	101,595
Construction materials
Segment Reporting
Segment revenue	119,991	116,248
Energy technology
Segment Reporting
Segment revenue	543	575
Operating Segments | Building products
Segment Reporting
Segment revenue	135,041	101,595
Depreciation and amortization	(11,715)	(8,860)
Operating income (loss)	11,400	11,675
Capital expenditures	11,400	4,401
Segment assets	683,538	676,012
Operating Segments | Construction materials
Segment Reporting
Segment revenue	119,991	116,248
Depreciation and amortization	(5,265)	(4,440)
Operating income (loss)	18,598	20,363
Capital expenditures	3,278	2,382
Segment assets	366,830	385,595
Operating Segments | Energy technology
Segment Reporting
Segment revenue	543	575
Depreciation and amortization	(155)	(323)
Operating income (loss)	(1,813)	(1,721)
Capital expenditures	20	0
Segment assets	39,929	43,412
Corporate, Non-Segment
Segment Reporting
Segment revenue	0	0
Depreciation and amortization	(707)	(159)
Operating income (loss)	(8,845)	(5,494)
Capital expenditures	842	902
Segment assets	$ 129,898	$ 133,424