Condensed Consolidating Financial Information - Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Revenue:
Revenue	$ 202,332	$ 179,725	$ 420,750	$ 379,322
Cost of revenue:
Total cost of revenue	147,455	132,584	301,602	276,494
Gross profit	54,877	47,141	119,148	102,828
Operating expenses:
Selling, general and administrative	37,882	34,351	72,764	66,380
Amortization	4,815	4,560	9,381	9,046
Total operating expenses	42,697	38,911	82,145	75,426
Operating income (loss)	12,180	8,230	37,003	27,402
Other income (expense):
Net interest expense	(8,056)	(35,965)	(16,273)	(47,917)
Equity in earnings of subsidiaries			0	0
Other, net	(12)	(33)	(81)	(302)
Total other income (expense), net	(8,068)	(35,998)	(16,354)	(48,219)
Income (loss) from continuing operations before income taxes	4,112	(27,768)	20,649	(20,817)
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)
Net income attributable to non-controlling interest	(283)	(259)	(579)	(504)
Net income (loss) attributable to Headwaters Incorporated	2,101	(25,457)	14,526	(18,618)
Building products
Revenue:
Revenue	129,195	106,406	261,040	223,940
Cost of revenue:
Total cost of revenue	93,174	79,481	186,333	163,673
Construction materials
Revenue:
Revenue	71,755	67,498	157,753	148,902
Cost of revenue:
Total cost of revenue	53,812	50,738	114,482	110,249
Energy technology
Revenue:
Revenue	1,382	5,821	1,957	6,480
Cost of revenue:
Total cost of revenue	469	2,365	787	2,572
Consolidation, Eliminations
Other income (expense):
Equity in earnings of subsidiaries	(11,021)	(12,325)	(29,647)	(34,125)
Total other income (expense), net	(11,021)	(12,325)	(29,647)	(34,125)
Income (loss) from continuing operations before income taxes	(11,021)	(12,325)	(29,647)	(34,125)
Income (loss) from continuing operations	(11,021)	(12,325)	(29,647)	(34,125)
Net income (loss)	(11,021)	(12,325)	(29,647)	(34,125)
Net income (loss) attributable to Headwaters Incorporated	(11,021)	(12,325)	(29,647)	(34,125)
Guarantor Subsidiaries
Revenue:
Revenue	189,919	169,254	396,137	357,710
Cost of revenue:
Total cost of revenue	138,763	125,519	284,345	261,755
Gross profit	51,156	43,735	111,792	95,955
Operating expenses:
Selling, general and administrative	29,331	26,636	57,025	52,438
Amortization	4,446	4,191	8,644	8,309
Total operating expenses	33,777	30,827	65,669	60,747
Operating income (loss)	17,379	12,908	46,123	35,208
Other income (expense):
Net interest expense	5	(60)	(95)	(104)
Other, net	(82)	(62)	(125)	(142)
Total other income (expense), net	(77)	(122)	(220)	(246)
Income (loss) from continuing operations before income taxes	17,302	12,786	45,903	34,962
Income tax benefit (provision)	(6,720)	(1,300)	(17,130)	(2,570)
Income (loss) from continuing operations	10,582	11,486	28,773	32,392
Loss from discontinued operations, net of income taxes				(67)
Net income (loss)	10,582	11,486	28,773	32,325
Net income (loss) attributable to Headwaters Incorporated	10,582	11,486	28,773	32,325
Guarantor Subsidiaries | Building products
Revenue:
Revenue	116,782	95,935	236,427	202,328
Cost of revenue:
Total cost of revenue	84,482	72,416	169,076	148,934
Guarantor Subsidiaries | Construction materials
Revenue:
Revenue	71,755	67,498	157,753	148,902
Cost of revenue:
Total cost of revenue	53,812	50,738	114,482	110,249
Guarantor Subsidiaries | Energy technology
Revenue:
Revenue	1,382	5,821	1,957	6,480
Cost of revenue:
Total cost of revenue	469	2,365	787	2,572
Non-Guarantor Subsidiaries
Revenue:
Revenue	12,413	10,471	24,613	21,612
Cost of revenue:
Total cost of revenue	8,692	7,065	17,257	14,739
Gross profit	3,721	3,406	7,356	6,873
Operating expenses:
Selling, general and administrative	1,859	1,618	3,553	3,192
Amortization	369	369	737	737
Total operating expenses	2,228	1,987	4,290	3,929
Operating income (loss)	1,493	1,419	3,066	2,944
Other income (expense):
Net interest expense	(3)		(3)
Other, net	70	29	44	(160)
Total other income (expense), net	67	29	41	(160)
Income (loss) from continuing operations before income taxes	1,560	1,448	3,107	2,784
Income tax benefit (provision)	(610)	(140)	(1,210)	(270)
Income (loss) from continuing operations	950	1,308	1,897	2,514
Loss from discontinued operations, net of income taxes	(228)	(210)	(444)	(210)
Net income (loss)	722	1,098	1,453	2,304
Net income attributable to non-controlling interest	(283)	(259)	(579)	(504)
Net income (loss) attributable to Headwaters Incorporated	439	839	874	1,800
Non-Guarantor Subsidiaries | Building products
Revenue:
Revenue	12,413	10,471	24,613	21,612
Cost of revenue:
Total cost of revenue	8,692	7,065	17,257	14,739
Parent Company
Operating expenses:
Selling, general and administrative	6,692	6,097	12,186	10,750
Total operating expenses	6,692	6,097	12,186	10,750
Operating income (loss)	(6,692)	(6,097)	(12,186)	(10,750)
Other income (expense):
Net interest expense	(8,058)	(35,905)	(16,175)	(47,813)
Equity in earnings of subsidiaries	11,021	12,325	29,647	34,125
Total other income (expense), net	2,963	(23,580)	13,472	(13,688)
Income (loss) from continuing operations before income taxes	(3,729)	(29,677)	1,286	(24,438)
Income tax benefit (provision)	5,830	4,220	13,240	5,820
Income (loss) from continuing operations	2,101	(25,457)	14,526	(18,618)
Net income (loss)	2,101	(25,457)	14,526	(18,618)
Net income (loss) attributable to Headwaters Incorporated	$ 2,101	$ (25,457)	$ 14,526	$ (18,618)