Condensed Consolidating Financial Information - Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Revenue:
Revenue	$ 255,575	$ 218,418
Cost of revenue:
Total cost of revenue	184,956	154,147
Gross profit	70,619	64,271
Operating expenses:
Selling, general and administrative	44,981	34,882
Amortization	6,298	4,566
Total operating expenses	51,279	39,448
Operating income	19,340	24,823
Other income (expense):
Net interest expense	(8,919)	(8,217)
Equity in earnings of subsidiaries	0
Other, net	154	(69)
Total other income (expense), net	(8,765)	(8,286)
Income from continuing operations before income taxes	10,575	16,537
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
Net income attributable to non-controlling interest	(161)	(296)
Net income attributable to Headwaters Incorporated	6,667	12,425
Building products
Revenue:
Revenue	135,041	101,595
Cost of revenue:
Total cost of revenue	96,529	69,552
Construction materials
Revenue:
Revenue	119,991	116,248
Cost of revenue:
Total cost of revenue	88,264	84,277
Energy technology
Revenue:
Revenue	543	575
Cost of revenue:
Total cost of revenue	163	318
Consolidation, Eliminations
Other income (expense):
Equity in earnings of subsidiaries	(17,565)	(18,626)
Total other income (expense), net	(17,565)	(18,626)
Income from continuing operations before income taxes	(17,565)	(18,626)
Income from continuing operations	(17,565)	(18,626)
Net income	(17,565)	(18,626)
Net income attributable to Headwaters Incorporated	(17,565)	(18,626)
Guarantor Subsidiaries
Revenue:
Revenue	240,613	206,218
Cost of revenue:
Total cost of revenue	173,205	145,582
Gross profit	67,408	60,636
Operating expenses:
Selling, general and administrative	34,012	27,694
Amortization	5,394	4,198
Total operating expenses	39,406	31,892
Operating income	28,002	28,744
Other income (expense):
Net interest expense	(124)	(100)
Other, net	(74)	(43)
Total other income (expense), net	(198)	(143)
Income from continuing operations before income taxes	27,804	28,601
Income tax provision	(10,480)	(10,410)
Income from continuing operations	17,324	18,191
Net income	17,324	18,191
Net income attributable to Headwaters Incorporated	17,324	18,191
Guarantor Subsidiaries | Building products
Revenue:
Revenue	120,079	89,395
Cost of revenue:
Total cost of revenue	84,778	60,987
Guarantor Subsidiaries | Construction materials
Revenue:
Revenue	119,991	116,248
Cost of revenue:
Total cost of revenue	88,264	84,277
Guarantor Subsidiaries | Energy technology
Revenue:
Revenue	543	575
Cost of revenue:
Total cost of revenue	163	318
Non-Guarantor Subsidiaries
Revenue:
Revenue	14,962	12,200
Cost of revenue:
Total cost of revenue	11,751	8,565
Gross profit	3,211	3,635
Operating expenses:
Selling, general and administrative	2,124	1,694
Amortization	904	368
Total operating expenses	3,028	2,062
Operating income	183	1,573
Other income (expense):
Net interest expense	(2)
Other, net	228	(26)
Total other income (expense), net	226	(26)
Income from continuing operations before income taxes	409	1,547
Income tax provision	(160)	(600)
Income from continuing operations	249	947
Income (loss) from discontinued operations, net of income taxes	153	(216)
Net income	402	731
Net income attributable to non-controlling interest	(161)	(296)
Net income attributable to Headwaters Incorporated	241	435
Non-Guarantor Subsidiaries | Building products
Revenue:
Revenue	14,962	12,200
Cost of revenue:
Total cost of revenue	11,751	8,565
Parent
Operating expenses:
Selling, general and administrative	8,845	5,494
Total operating expenses	8,845	5,494
Operating income	(8,845)	(5,494)
Other income (expense):
Net interest expense	(8,793)	(8,117)
Equity in earnings of subsidiaries	17,565	18,626
Total other income (expense), net	8,772	10,509
Income from continuing operations before income taxes	(73)	5,015
Income tax provision	6,740	7,410
Income from continuing operations	6,667	12,425
Net income	6,667	12,425
Net income attributable to Headwaters Incorporated	$ 6,667	$ 12,425