Acquisitions (Details) (USD $)	3 Months Ended		9 Months Ended			0 Months Ended	9 Months Ended			3 Months Ended			9 Months Ended		12 Months Ended	0 Months Ended	9 Months Ended			9 Months Ended			0 Months Ended			3 Months Ended	1 Months Ended
	Jun. 30, 2014 item	Jun. 30, 2013	Jun. 30, 2014 item	Jun. 30, 2013	Sep. 30, 2013	Dec. 31, 2012 Kleer Lumber Inc [Member]	Jun. 30, 2014 Kleer Lumber Inc [Member]	Dec. 31, 2012 Kleer Lumber Inc [Member]	Dec. 31, 2012 Kleer Lumber Inc [Member] Trade Names [Member]	Dec. 31, 2012 Kleer Lumber Inc [Member] Customer Relationships [Member]	Jun. 30, 2014 Acquisitions2014 [Member]	Jun. 30, 2013 Acquisitions2014 [Member]	Jun. 30, 2014 Acquisitions2014 [Member]	Jun. 30, 2013 Acquisitions2014 [Member]	Sep. 30, 2013 Acquisitions2014 [Member]	Dec. 12, 2013 Entegra [Member]	Jun. 30, 2014 Entegra [Member]	Dec. 12, 2013 Entegra [Member]	Dec. 12, 2013 Entegra [Member] Trade Names [Member]	Jun. 30, 2014 Entegra [Member] Customer Relationships [Member]	Dec. 12, 2013 Entegra [Member] Customer Relationships [Member]	Dec. 12, 2013 Roof Tile Inc [Member]	May 16, 2014 Gerard [Member]	Jun. 30, 2014 Gerard [Member] item	May 16, 2014 Gerard [Member]	Mar. 31, 2014 Other Business Acquisitions [Member]	Jul. 31, 2014 Other Business Acquisitions [Member] Subsequent Event [Member]
Acquisition
Total cash consideration of acquisition						$ 43,300,000										$ 57,500,000							$ 28,000,000			$ 3,100,000	$ 7,400,000
Fees for advisory, legal and other professional services								900,000			600,000		600,000				400,000							200,000
Number of primary metal profiles sold																								7
Number of product categories in niche roofing	3		3
Estimated fair values of assets acquired and liabilities assumed
Current assets								5,818,000										8,260,000							9,358,000
Current liabilities								(3,093,000)										(3,422,000)							(5,637,000)
Property, plant and equipment								4,098,000										10,589,000							6,617,000
Goodwill	186,040,000		186,040,000		137,198,000			20,527,000										30,089,000
Goodwill and intangible assets																									17,664,000
Net assets acquired								43,250,000										70,716,000							28,002,000
Less non-controlling interest																	(13,239,000)	(13,239,000)
Net assets attributable to Headwaters																		57,477,000
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	223,399,000	197,030,000	545,526,000	487,591,000							15,200,000		26,000,000		0
Net income (loss)	10,893,000	11,016,000	(623,000)	(3,116,000)							1,700,000		2,600,000		0
Pro forma consolidated revenue and net income (loss)
Revenue											227,360,000	212,890,000	572,310,000	531,472,000
Net loss											11,309,000	11,728,000	1,945,000	(1,440,000)
Nonrecurring expense related to the fair value adjustment to acquisition-date inventory											1,200,000		1,200,000
Non-controlling interest in consolidated subsidiary
Estimated fair value as of acquisition date																	13,239,000	13,239,000
Net income attributable to non-controlling interest	389,000	0	619,000	0													619,000
Dividend																	(318,000)
Fair value adjustment	158,000	0	158,000	0													158,000
Balance	$ 13,698,000		$ 13,698,000		$ 0												$ 13,698,000