DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Number of Operating Segments	3
Number of companies	2
Cash In Non U.S. Bank Accounts	$ 21,400	$ 15,900
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Fair Value Of Insurance Contracts	3,789	4,183
Trading Securities	1,194	697
Derivative, Number of Instruments Held	0
Contracts Revenue	750
Contracts Weighted Average Rate Price (in Dollars per share)	$ 1.07
Foreign Currency Transaction Gain (Loss), Realized	46
Defined Benefit Plan, Fair Value of Plan Assets	153,731	160,833
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	20,113	23,202
Contract Period	1 year
Customer Program Reserves And Cash Discounts Netted Against Accounts Receivable	6,556	8,653
Depreciation, Depletion and Amortization, Nonproduction	62,911	58,216	52,844
Accumulated Capitalized Interest Costs	4,030	2,975	2,250
Original Cost Of Fully Depreciated Property Plant And Equipment	216,000
Description of Fair Value Calculation	Griffon used five year projections and a 3.0% terminal value to which discount rates between 9% and 11.25% were applied to calculate each unit's fair value.
Fair Value Projections	5 years
Fair Value Terminal Value	3.00%
Goodwill, Impairment Loss	0	0	0
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	0	0	0
Unrecognized Tax Benefits	10,520	11,876	12,910
Research and Development Arrangement, Contract to Perform for Others, Costs Incurred, Gross	22,400	23,600	23,900
Shipping, Handling and Transportation Costs	39,600	40,200	41,600
Advertising Revenue Cost	23,000	22,000	23,000
General And Product Liability Claims Maximum Amount Of Per Occurrence	350
Workers Compensation And Automobile Liability Claims Maximum Amount Of Per Occurrence	250
Health Related Claims Amount Of Per Participant, Per Year	300
U S Government [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Percentage of Consolidated Accounts Receivable	19.00%
P And G [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Percentage of Consolidated Accounts Receivable	12.00%
Home Depot [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Percentage of Consolidated Accounts Receivable	10.00%
Building and Building Improvements [Member] | Maximum [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Building and Building Improvements [Member] | Minimum [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Machinery and Equipment [Member] | Maximum [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Machinery and Equipment [Member] | Minimum [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Other Income [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	81
Senior Notes [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			7.125%
Long-term Debt, Fair Value	583,000
Convertible Debt 2017 [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Long-term Debt, Fair Value	$ 112,600
Maximum [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Maturity Period of Highly Liquid Investments	3 months
Contracts Expiration Days	90 days
Fair Value Discount Rates	11.25%
Finite-Lived Intangible Asset, Useful Life	25 years
Minimum [Member]
DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) [Line Items]
Contracts Expiration Days	15 days
Fair Value Discount Rates	9.00%
Finite-Lived Intangible Asset, Useful Life	8 years