Acquisitions (Details) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended	6 Months Ended		3 Months Ended	0 Months Ended	6 Months Ended		6 Months Ended	3 Months Ended			6 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013	Dec. 31, 2012 Kleer Lumber, Inc.	Mar. 31, 2014 Kleer Lumber, Inc.	Dec. 31, 2012 Kleer Lumber, Inc. Trade name	Dec. 31, 2012 Kleer Lumber, Inc. Customer relationships	Dec. 12, 2013 Roof Tile, Inc.	Mar. 31, 2014 Roof Tile, Inc.	Mar. 31, 2014 Roof Tile, Inc. Trade name	Mar. 31, 2014 Roof Tile, Inc. Customer relationships	Mar. 31, 2014 Other	Mar. 31, 2014 2014 acquisitions	Mar. 31, 2013 2014 acquisitions	Mar. 31, 2014 2014 acquisitions	Mar. 31, 2013 2014 acquisitions	Sep. 30, 2013 2014 acquisitions
Acquisition
Total cash consideration of acquisition						$ 43,300,000				$ 57,500,000				$ 3,100,000
Fees for advisory, legal and other professional services						900,000					300,000				400,000		400,000
Estimated fair values of assets acquired and liabilities assumed
Current assets						5,818,000					8,186,000
Current liabilities						(3,093,000)					(3,422,000)
Property, plant and equipment						4,098,000					10,589,000
Goodwill	168,489,000		168,489,000		137,198,000	20,527,000					30,112,000
Net assets acquired						43,250,000					70,665,000
Less non-controlling interest											(13,146,000)
Net assets attributable to Headwaters											57,519,000
Intangible assets acquired:
Finite lived intangible assets									11,100,000				18,600,000
Indefinite lived intangible assets								4,800,000				6,600,000
Estimated useful lives									15 years				15 years
Period over which goodwill is expected to be deductible for tax purpose							15 years				15 years
Percentage of equity interests acquired										80.00%
Noncontrolling equity interest (as a percent)											20.00%
Minimum period following the acquisition date after which remaining noncontrolling equity interest may be acquired											5 years
Minimum period following the acquisition date after which the noncontrolling owners may require remaining noncontrolling equity interests to be acquired											18 months
Revenue	156,512,000	140,988,000	322,127,000	290,561,000											9,000,000		11,000,000		0
Net loss	(10,318,000)	(8,260,000)	(11,746,000)	(14,132,000)											1,000,000		1,000,000		0
Pro forma consolidated revenue and net income (loss)
Revenue															156,715,000	148,701,000	330,730,000	305,919,000
Net loss															(10,332,000)	(6,906,000)	(9,695,000)	(12,714,000)
Nonrecurring expense related to the fair value adjustment to acquisition-date inventory															500,000		500,000
Non-controlling interest in consolidated subsidiary
Estimated fair value as of acquisition date											13,146,000
Net income attributable to non-controlling interest	236,000	0	230,000	0							230,000
Non-controlling interest	$ 13,376,000		$ 13,376,000		$ 0						$ 13,376,000