Condensed Consolidating Financial Information (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Revenue:
Light building products									$ 472,434	$ 394,324	$ 339,632
Heavy construction materials									309,337	293,000	281,672
Energy technology									9,676	15,252	11,483
Total revenue	245,921	223,399	156,512	165,615	214,985	197,030	140,988	149,573	791,447	702,576	632,787
Cost of revenue:
Light building products									336,283	283,128	241,669
Heavy construction materials									224,888	219,996	210,158
Energy technology									4,583	6,970	5,893
Total cost of revenue									565,754	510,094	457,720
Gross profit	78,577	67,672	38,551	40,893	64,321	58,505	32,411	37,245	225,693	192,482	175,067
Operating expenses:
Amortization									21,319	20,230	20,675
Selling, general and administrative									137,650	117,841	119,989
Total operating expenses									158,969	138,071	140,664
Operating income (loss)									66,724	54,411	34,403
Other income (expense):
Net interest expense									(46,329)	(42,566)	(52,678)
Equity in earnings (loss) of subsidiaries									0	0	0
Other, net									(348)	364	(7,493)
Total other income (expense), net									(46,677)	(42,202)	(60,171)
Income (loss) from continuing operations before income taxes									20,047	12,209	(25,768)
Income tax benefit (provision)									(3,574)	(3,924)	(661)
Income (loss) from continuing operations									16,473	8,285	(26,429)
Loss from discontinued operations, net of income taxes									(415)	(1,148)	(35,819)
Net income (loss)	16,681	10,893	(10,082)	(1,434)	10,253	11,016	(8,260)	(5,872)	16,058	7,137	(62,248)
Net income attributable to non-controlling interest									(774)	0	0
Net income (loss) attributable to Headwaters Incorporated									15,284	7,137	(62,248)
Consolidation, Eliminations
Other income (expense):
Equity in earnings (loss) of subsidiaries									(62,719)	(47,117)	13,536
Total other income (expense), net									(62,719)	(47,117)	13,536
Income (loss) from continuing operations before income taxes									(62,719)	(47,117)	13,536
Income (loss) from continuing operations									(62,719)	(47,117)	13,536
Net income (loss)									(62,719)	(47,117)	13,536
Net income (loss) attributable to Headwaters Incorporated									(62,719)	(47,117)	13,536
Guarantor Subsidiaries | Reportable Legal Entities
Revenue:
Light building products									438,473	394,324	339,632
Heavy construction materials									309,337	293,000	281,672
Energy technology									9,676	15,252	11,483
Total revenue									757,486	702,576	632,787
Cost of revenue:
Light building products									312,220	283,128	241,669
Heavy construction materials									224,888	219,996	210,158
Energy technology									4,583	6,970	5,893
Total cost of revenue									541,691	510,094	457,720
Gross profit									215,795	192,482	175,067
Operating expenses:
Amortization									20,231	20,230	20,675
Selling, general and administrative									108,602	96,478	94,630
Total operating expenses									128,833	116,708	115,305
Operating income (loss)									86,962	75,774	59,762
Other income (expense):
Net interest expense									(349)	(54)	(80)
Intercompany interest income (expense)									(22,737)	(23,434)	(25,945)
Other, net									(24)	329	(9,972)
Total other income (expense), net									(23,110)	(23,159)	(35,997)
Income (loss) from continuing operations before income taxes									63,852	52,615	23,765
Income tax benefit (provision)									(3,296)	(4,350)	(1,482)
Income (loss) from continuing operations									60,556	48,265	22,283
Loss from discontinued operations, net of income taxes									(415)	(1,148)	(35,819)
Net income (loss)									60,141	47,117	(13,536)
Net income (loss) attributable to Headwaters Incorporated									60,141	47,117	(13,536)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenue:
Light building products									33,961
Total revenue									33,961
Cost of revenue:
Light building products									24,063
Total cost of revenue									24,063
Gross profit									9,898
Operating expenses:
Amortization									1,088
Selling, general and administrative									4,209
Total operating expenses									5,297
Operating income (loss)									4,601
Other income (expense):
Net interest expense									(2)
Other, net									(324)
Total other income (expense), net									(326)
Income (loss) from continuing operations before income taxes									4,275
Income tax benefit (provision)									(923)
Income (loss) from continuing operations									3,352
Net income (loss)									3,352
Net income attributable to non-controlling interest									(774)
Net income (loss) attributable to Headwaters Incorporated									2,578
Parent Company | Reportable Legal Entities
Operating expenses:
Selling, general and administrative									24,839	21,363	25,359
Total operating expenses									24,839	21,363	25,359
Operating income (loss)									(24,839)	(21,363)	(25,359)
Other income (expense):
Net interest expense									(45,978)	(42,512)	(52,598)
Intercompany interest income (expense)									22,737	23,434	25,945
Equity in earnings (loss) of subsidiaries									62,719	47,117	(13,536)
Other, net										35	2,479
Total other income (expense), net									39,478	28,074	(37,710)
Income (loss) from continuing operations before income taxes									14,639	6,711	(63,069)
Income tax benefit (provision)									645	426	821
Income (loss) from continuing operations									15,284	7,137	(62,248)
Net income (loss)									15,284	7,137	(62,248)
Net income (loss) attributable to Headwaters Incorporated									$ 15,284	$ 7,137	$ (62,248)