Condensed Consolidating Financial Information - Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Revenue:
Revenue	$ 218,418	$ 199,597
Cost of revenue:
Total cost of revenue	154,147	143,910
Gross profit	64,271	55,687
Operating expenses:
Selling, general and administrative	34,882	32,029
Amortization	4,566	4,486
Total operating expenses	39,448	36,515
Operating income (loss)	24,823	19,172
Other income (expense):
Net interest expense	(8,217)	(11,952)
Equity in earnings of subsidiaries	0	0
Other, net	(69)	(269)
Total other income (expense), net	(8,286)	(12,221)
Income from continuing operations before income taxes	16,537	6,951
Income tax benefit (provision)	(3,600)	200
Income from continuing operations	12,937	7,151
Loss from discontinued operations, net of income taxes	(216)	(67)
Net income	12,721	7,084
Net income attributable to non-controlling interest	(296)	(245)
Net income attributable to Headwaters Incorporated	12,425	6,839
Building products
Revenue:
Revenue	131,845	117,534
Cost of revenue:
Total cost of revenue	93,159	84,192
Construction materials
Revenue:
Revenue	85,998	81,404
Cost of revenue:
Total cost of revenue	60,670	59,511
Energy technology
Revenue:
Revenue	575	659
Cost of revenue:
Total cost of revenue	318	207
Consolidation, Eliminations
Other income (expense):
Equity in earnings of subsidiaries	(18,626)	(21,800)
Total other income (expense), net	(18,626)	(21,800)
Income from continuing operations before income taxes	(18,626)	(21,800)
Income from continuing operations	(18,626)	(21,800)
Net income	(18,626)	(21,800)
Net income attributable to Headwaters Incorporated	(18,626)	(21,800)
Guarantor Subsidiaries
Revenue:
Revenue	206,218	188,456
Cost of revenue:
Total cost of revenue	145,582	136,236
Gross profit	60,636	52,220
Operating expenses:
Selling, general and administrative	27,694	25,802
Amortization	4,198	4,118
Total operating expenses	31,892	29,920
Operating income (loss)	28,744	22,300
Other income (expense):
Net interest expense	(100)	(44)
Other, net	(43)	(80)
Total other income (expense), net	(143)	(124)
Income from continuing operations before income taxes	28,601	22,176
Income tax benefit (provision)	(10,410)	(1,270)
Income from continuing operations	18,191	20,906
Loss from discontinued operations, net of income taxes		(67)
Net income	18,191	20,839
Net income attributable to Headwaters Incorporated	18,191	20,839
Guarantor Subsidiaries | Building products
Revenue:
Revenue	119,645	106,393
Cost of revenue:
Total cost of revenue	84,594	76,518
Guarantor Subsidiaries | Construction materials
Revenue:
Revenue	85,998	81,404
Cost of revenue:
Total cost of revenue	60,670	59,511
Guarantor Subsidiaries | Energy technology
Revenue:
Revenue	575	659
Cost of revenue:
Total cost of revenue	318	207
Non-Guarantor Subsidiaries
Revenue:
Revenue	12,200	11,141
Cost of revenue:
Total cost of revenue	8,565	7,674
Gross profit	3,635	3,467
Operating expenses:
Selling, general and administrative	1,694	1,574
Amortization	368	368
Total operating expenses	2,062	1,942
Operating income (loss)	1,573	1,525
Other income (expense):
Other, net	(26)	(189)
Total other income (expense), net	(26)	(189)
Income from continuing operations before income taxes	1,547	1,336
Income tax benefit (provision)	(600)	(130)
Income from continuing operations	947	1,206
Loss from discontinued operations, net of income taxes	(216)
Net income	731	1,206
Net income attributable to non-controlling interest	(296)	(245)
Net income attributable to Headwaters Incorporated	435	961
Non-Guarantor Subsidiaries | Building products
Revenue:
Revenue	12,200	11,141
Cost of revenue:
Total cost of revenue	8,565	7,674
Parent Company
Operating expenses:
Selling, general and administrative	5,494	4,653
Total operating expenses	5,494	4,653
Operating income (loss)	(5,494)	(4,653)
Other income (expense):
Net interest expense	(8,117)	(11,908)
Equity in earnings of subsidiaries	18,626	21,800
Total other income (expense), net	10,509	9,892
Income from continuing operations before income taxes	5,015	5,239
Income tax benefit (provision)	7,410	1,600
Income from continuing operations	12,425	6,839
Net income	12,425	6,839
Net income attributable to Headwaters Incorporated	$ 12,425	$ 6,839