Earnings Per Share - Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Income from continuing operations	$ 5,126	$ 2,612	$ 11,801	$ 15,549
Income from continuing operations attributable to non-controlling interest	(591)	(283)	(752)	(579)
Numerator for basic and diluted earnings per share from continuing operations — income from continuing operations attributable to Headwaters Incorporated	4,535	2,329	11,049	14,970
Numerator for basic and diluted earnings per share from discontinued operations - income (loss) from discontinued operations, net of income taxes	6	(228)	159	(444)
Numerator for basic and diluted earnings per share — net income attributable to Headwaters Incorporated	$ 4,541	$ 2,101	$ 11,208	$ 14,526
Denominator:
Denominator for basic earnings per share - weighted-average shares outstanding	74,835	73,818	74,536	73,804
Effect of dilutive securities - shares issuable upon exercise of options and SARs and vesting of restricted stock	1,147	1,523	1,291	1,549
Denominator for diluted earnings per share - weighted-average shares outstanding after assumed exercises and vesting	75,982	75,341	75,827	75,353
Basic income (loss) per share attributable to Headwaters Incorporated:
From continuing operations (in dollars per share)	$ 0.06	$ 0.03	$ 0.15	$ 0.21
From discontinued operations (in dollars per share)	0.00	0.00	0.00	(0.01)
Basic income per share (in dollars per share)	0.06	0.03	0.15	0.20
Diluted income (loss) per share attributable to Headwaters Incorporated:
From continuing operations (in dollars per share)	0.06	0.03	0.15	0.20
From discontinued operations (in dollars per share)	0.00	0.00	0.00	(0.01)
Diluted income per share (in dollars per share)	$ 0.06	$ 0.03	$ 0.15	$ 0.19