LONG-TERM DEBT (Detail)	3 Months Ended			9 Months Ended			6 Months Ended	12 Months Ended					3 Months Ended				9 Months Ended				12 Months Ended	3 Months Ended				9 Months Ended				12 Months Ended		3 Months Ended				9 Months Ended				12 Months Ended		3 Months Ended				9 Months Ended				12 Months Ended			3 Months Ended				9 Months Ended				12 Months Ended	3 Months Ended				9 Months Ended					3 Months Ended				9 Months Ended				12 Months Ended			3 Months Ended				6 Months Ended	9 Months Ended									9 Months Ended								12 Months Ended
	Jun. 30, 2012 USD ($)	Jun. 30, 2011 USD ($)	Mar. 31, 2011 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2011 USD ($)	Jun. 30, 2012 Subsequent Event [Member] Convertible Debt 2017 [Member]	Mar. 31, 2012 Brazilian CDI [Member] Foreign Term Loan [Member]	Sep. 30, 2011 Multicurrency Subfacility [Member] Revolver Due 2016 [Member] USD ($)	Sep. 30, 2011 Subfacility With Limit [Member] Revolver Due 2016 [Member] USD ($)	Sep. 30, 2011 Swingline Subfacility [Member] Revolver Due 2016 [Member] USD ($)	Sep. 30, 2011 Margin Rate [Member] Revolver Due 2016 [Member]	Sep. 30, 2011 LIBOR Rate [Member]	Jun. 30, 2012 Senior Notes [Member]		Jun. 30, 2011 Senior Notes [Member]		Jun. 30, 2012 Senior Notes [Member]		Jun. 30, 2011 Senior Notes [Member]		Sep. 30, 2011 Senior Notes [Member] USD ($)	Jun. 30, 2012 Convertible Debt 2017 [Member] USD ($)		Jun. 30, 2011 Convertible Debt 2017 [Member]		Jun. 30, 2012 Convertible Debt 2017 [Member] USD ($)		Jun. 30, 2011 Convertible Debt 2017 [Member]		Sep. 30, 2010 Convertible Debt 2017 [Member] USD ($)	Sep. 30, 2011 Convertible Debt 2017 [Member] USD ($)	Jun. 30, 2012 Real Estate Mortgages Loan [Member]		Jun. 30, 2011 Real Estate Mortgages Loan [Member]		Jun. 30, 2012 Real Estate Mortgages Loan [Member]		Jun. 30, 2011 Real Estate Mortgages Loan [Member]		Sep. 30, 2011 Real Estate Mortgages Loan [Member] USD ($)	Sep. 30, 2011 Other Real Estate Mortgages Loan [Member]	Jun. 30, 2012 Employee Stock Ownership Plan Loan [Member] USD ($)		Jun. 30, 2011 Employee Stock Ownership Plan Loan [Member]		Jun. 30, 2012 Employee Stock Ownership Plan Loan [Member] USD ($)		Jun. 30, 2011 Employee Stock Ownership Plan Loan [Member]		Sep. 30, 2011 Employee Stock Ownership Plan Loan [Member] USD ($)	Sep. 30, 2009 Employee Stock Ownership Plan Loan [Member]	Jun. 30, 2012 Employee Stock Ownership Plan Additional Loan Agreement [Member] USD ($)	Jun. 30, 2012 Capital Lease Obligations [Member]		Jun. 30, 2011 Capital Lease Obligations [Member]		Jun. 30, 2012 Capital Lease Obligations [Member]		Jun. 30, 2011 Capital Lease Obligations [Member]		Sep. 30, 2007 Capital Lease Obligations [Member] USD ($)	Jun. 30, 2012 Convertible Debt 2023 [Member] USD ($)		Jun. 30, 2011 Convertible Debt 2023 [Member]		Jun. 30, 2012 Convertible Debt 2023 [Member] USD ($)		Jun. 30, 2011 Convertible Debt 2023 [Member]		Sep. 30, 2011 Convertible Debt 2023 [Member] USD ($)	Jun. 30, 2012 Revolver Due 2012 [Member]		Jun. 30, 2011 Revolver Due 2012 [Member]		Jun. 30, 2012 Revolver Due 2012 [Member]		Jun. 30, 2011 Revolver Due 2012 [Member]		Sep. 30, 2011 Revolver Due 2012 [Member] EUR (€)	Sep. 30, 2011 Term Loan [Member] EUR (€)	Jun. 30, 2012 Term Loan [Member] EUR (€)	Jun. 30, 2012 Foreign Term Loan [Member] USD ($)		Jun. 30, 2011 Foreign Term Loan [Member]		Mar. 31, 2012 Foreign Term Loan [Member] USD ($)	Jun. 30, 2012 Foreign Term Loan [Member] USD ($)		Jun. 30, 2011 Foreign Term Loan [Member]		Jun. 30, 2012 Term Loan 2016 [Member] USD ($)		Jun. 30, 2011 Term Loan 2016 [Member]		Sep. 30, 2011 Term Loan 2016 [Member] USD ($)	Jun. 30, 2012 Asset Based Loan [Member] USD ($)		Jun. 30, 2011 Asset Based Loan [Member]		Jun. 30, 2012 Revolver Due 2013 [Member]		Jun. 30, 2011 Revolver Due 2013 [Member]		Sep. 30, 2008 Revolver Due 2013 [Member] USD ($)	Sep. 30, 2011 Revolver Due 2016 [Member] USD ($)	Jun. 30, 2012 Revolver Due 2016 [Member] USD ($)
Proceeds from Issuance of Long-term Debt				$ 4,000,000	$ 640,963,000																$ 550,000,000									$ 100,000,000										$ 11,834,000										$ 20,000,000											$ 14,290,000																									$ 4,000,000					$ 375,000,000					$ 125,000,000
Debt Instrument Redemption Price Description																					The Senior Notes can be redeemed prior to April 1, 2014 at a price of 100% of principal plus a make-whole premium and accrued interest; on or after April 1, 2014, the Senior Notes can be redeemed at a certain price (declining from 105.344% of principal on or after April 1, 2014 to 100% of principal on or after April 1, 2017), plus accrued interest.
Proceeds from Lines of Credit								50,000,000	50,000,000	30,000,000																																																																																															200,000,000
Line of Credit Facility, Interest Rate During Period											1.75%	2.75%
Line of Credit Facility, Amount Outstanding																																																																																	1,000	1,346,000					1,346,000																			21,516,000
Line of Credit Facility, Current Borrowing Capacity																																																																																	9,000																									178,484,000
Debt Conversion, Converted Instrument, Shares Issued (in Shares)																														67.0799																				1,874,737
Debt Conversion, Converted Instrument, Amount																														1,000,000																				19,973,000
Debt Instrument, Convertible, Conversion Price (in Dollars per share)																														$ 14.91
Debt Instrument Coversion Premium																														23.00%
Closing Price Per Share Of Common Stock (in Dollars per share)																														$ 12.12
Debt Instrument, Convertible, Terms of Conversion Feature																														When a cash dividend is declared that would result in an adjustment to the conversion ratio of less than 1%, any adjustment to the conversion ratio is deferred until the first to occur of (i) actual conversion, (ii) the 42nd trading day prior to maturity of the notes, and (iii) such time as the cumulative adjustment equals or exceeds 1%.																																				An adjustment to the conversion rate will be required as the result of payment of a cash dividend only if such adjustment would be greater than 1% (or at such time as the cumulative impact on the conversion rate reaches 1% in the aggregate).
Aggregate Dividends Per Share (in Dollars per share)																						$ 0.08				$ 0.08
Debt Instrument Convertible Conversion Rate						0.90%																																																								0.90%				0.90%
Nonconvertible Debt Borrowing Rate To Discount																														8.75%
Debt Component																						75,437,000				75,437,000
Discount Of Debt Component																						24,563,000				24,563,000
Capital In Excess Of Par Component Net Of Tax																						15,720,000				15,720,000					15,720,000
Debt Instrument, Description of Variable Rate Basis																																								The loans bear interest at a rate of LIBOR plus 3% with the option to swap to a fixed rate. Griffon has other real estate mortgages, collateralized by real property, which bear interest at 6.3% and mature in 2016.										The loan bears interest at a) LIBOR plus 2.5% or b) the lender's prime rate, at Griffon's option.																													The facility accrues interest at Euribor plus 2.1% per annum	the term loan accrues interest at Euribor plus 2.2% per annum.
Debt Instrument, Interest Rate During Period							104.50%						7.40%	[1]	7.10%	[1]	7.40%	[1]	7.50%	[1]		9.20%	[2]	9.20%	[2]	9.20%	[2]	9.30%	[2]			5.60%	[3]	5.20%	[3]	5.60%	[3]	5.60%	[3]		6.30%	3.00%	[4]	2.90%	[4]	3.00%	[4]	2.50%	[4]				5.30%	[5]	5.30%	[5]	5.30%	[5]	5.40%	[5]		4.00%	[6]	4.00%	[6]	4.00%	[6]	4.00%	[6]			[7]		[7]		[7]		[7]				10.90%	[8]		[8]		10.60%	[8]		[8]		[9]	9.50%	[9]			[9]	6.20%	[9]		[10]	1.60%	[10]
Debt Instrument, Periodic Payment, Principal																																														250,000
Debt Instrument Balloon Payment																																														15,223,000
Employee Stock Ownership Plan (ESOP), Debt Structure, Employer Loan Guarantee																																										19,223,000				19,223,000
Employee Stock Ownership Plan Debt Structure Required Quarterly Principal Payments																																										156,000
Employee Stock Ownership Plan Debt Structure Balance Of Loan For Interest																																										3,125,000				3,125,000						3,906,000
Stock Issued During Period, Shares, New Issues (in Shares)																																																			547,605
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate																																																													5.10%
Convertible Subordinated Debt																																																														532,000				532,000				532,000
Debt Instrument, Interest Rate, Stated Percentage																																																														4.00%				4.00%
Dividends Payable, Amount Per Share (in Dollars per share)	$ 0.02			$ 0.02																																																										$ 0.08				$ 0.08
Proceeds from Long-term Lines of Credit																																																																															10,000,000	20,000,000																								100,000,000
Percentage Of Guaranty By Plastics																																																																																						50.00%
Maintains Maximum Amount Of Line Of Credit																																																																																		1,700,000					1,700,000
Line of Credit Facility, Interest Rate Description																																																																																							6.0%
Derivative, Notional Amount																																																																																															200,000,000
Derivative, Fixed Interest Rate																																																																																															2.085%
Gains (Losses) on Extinguishment of Debt	0	0	(26,164,000)	0	(26,164,000)
Deferred Financing Charges And Original Issuer Discounts			21,617,000
Premium On Term Loan			3,703,000
Swap And Other Breakage Costs			$ 844,000

[1] On March 17, 2011, in an unregistered offering through a private placement under Rule 144A, Griffon issued, at par, $550,000 of 7.125% Senior Notes due in 2018; interest is payable semi-annually. On August 9, 2011, Griffon exchanged all of the Senior Notes for substantially identical Senior Notes registered under the Securities Act of 1933 ("Senior Notes"), via an exchange offer.The Senior Notes can be redeemed prior to April 1, 2014 at a price of 100% of principal plus a make-whole premium and accrued interest; on or after April 1, 2014, the Senior Notes can be redeemed at a certain price (declining from 105.344% of principal on or after April 1, 2014 to 100% of principal on or after April 1, 2017), plus accrued interest. Proceeds from the Senior Notes were used to pay down the outstanding borrowings under a senior secured term loan facility and two senior secured revolving credit facilities of certain of the Company's subsidiaries. The Senior Notes are senior unsecured obligations of Griffon guaranteed by certain domestic subsidiaries, and are subject to certain covenants, limitations and restrictions.On March 18, 2011, Griffon entered into a five-year $200,000 Revolving Credit Facility ("Credit Agreement"), which includes a letter of credit sub-facility with a limit of $50,000, a multi-currency sub-facility of $50,000 and a swingline sub-facility with a limit of $30,000. Borrowings under the Credit Agreement may be repaid and re-borrowed at any time, subject to final maturity of the facility or the occurrence of a default or event of default under the Credit Agreement. Interest is payable on borrowings at either a LIBOR or base rate benchmark rate plus an applicable margin, which will adjust based on financial performance. The margins are 1.75% for base rate loans and 2.75% for LIBOR loans, in each case without a floor. The Credit Agreement has certain financial maintenance tests including a maximum total leverage ratio, a maximum senior secured leverage ratio and a minimum interest coverage ratio as well as customary affirmative and negative covenants and events of default. The Credit Agreement also includes certain restrictions, such as limitations on the incurrence of indebtedness and liens and the making of restricted payments and investments. Borrowings under the Credit Agreement are guaranteed by certain domestic subsidiaries and are secured, on a first priority basis, by substantially all assets of the Company and the guarantors. At June 30, 2012, there were $21,516 of standby letters of credit outstanding under the Credit Agreement; $178,484 was available for borrowing at that date.

[2] On December 21, 2009, Griffon issued $100,000 principal of 4% convertible subordinated notes due 2017 (the "2017 Notes"). The initial conversion rate of the 2017 Notes was 67.0799 shares of Griffon's common stock per $1,000 principal amount of notes, corresponding to an initial conversion price of $14.91 per share, a 23% conversion premium over the $12.12 closing price on December 15, 2009. When a cash dividend is declared that would result in an adjustment to the conversion ratio of less than 1%, any adjustment to the conversion ratio is deferred until the first to occur of (i) actual conversion, (ii) the 42nd trading day prior to maturity of the notes, and (iii) such time as the cumulative adjustment equals or exceeds 1%. As of September 25, 2012, aggregate dividends of $0.08 per share would result in a cumulative change in the conversion rate of approximately 0.9%. Griffon used 8.75% as the nonconvertible debt-borrowing rate to discount the 2017 Notes and will amortize the debt discount through January 2017. At issuance, the debt component of the 2017 Notes was $75,437 and debt discount was $24,563. At June 30, 2012 and September 30, 2011, the 2017 Notes had a capital in excess of par component, net of tax, of $15,720.

[3] On December 20, 2010, Griffon entered into two second lien real estate mortgages to secure new loans totaling $11,834. The loans mature in February 2016, are collateralized by the related properties and are guaranteed by Griffon. The loans bear interest at a rate of LIBOR plus 3% with the option to swap to a fixed rate.Griffon has other real estate mortgages, collateralized by real property, which bear interest at 6.3% and mature in 2016. On October 3, 2011, the mortgage at Russia, Ohio was paid in full, on maturity.

[4] Griffon's Employee Stock Ownership Plan ("ESOP") entered into a loan agreement in August 2010 to borrow $20,000 over a one-year period. The proceeds were used to purchase 1,874,737 shares of Griffon common stock in the open market for $19,973. The loan bears interest at a) LIBOR plus 2.5% or b) the lender's prime rate, at Griffon's option. In November 2011, Griffon exercised an option to convert the outstanding loan to a five-year term loan; principal is payable in quarterly installments of $250, beginning December 2011, with a balloon payment of $15,223 due at maturity (November 2016). The loan is secured by shares purchased with the proceeds of the loan, and repayment is guaranteed by Griffon. At June 30, 2012, $19,223 was outstanding.In addition, the ESOP has a loan agreement, guaranteed by Griffon, which requires quarterly principal payments of $156 and interest through the extended expiration date of December 2013 at which time the $3,125 balance of the loan, and any outstanding interest, will be payable. The primary purpose of this loan was to purchase 547,605 shares of Griffon's common stock in October 2008. The loan is secured by shares purchased with the proceeds of the loan, and repayment is guaranteed by Griffon. The loan bears interest at rates based upon the prime rate or LIBOR. At June 30, 2012, $3,906 was outstanding.

[5] In October 2006, CBP entered into a capital lease totaling $14,290 for real estate in Troy, Ohio. The lease matures in 2021, bears interest at a fixed rate of 5.1%, is secured by a mortgage on the real estate and is guaranteed by Griffon.

[6] At June 30, 2012 and September 30, 2011, Griffon had $532 of 4% convertible subordinated notes due 2023 (the "2023 Notes") outstanding. Holders of the 2023 Notes may require Griffon to repurchase all or a portion of their 2023 Notes on July 18, 2013 and 2018, if Griffon's common stock price is below the conversion price of the 2023 Notes, as well as upon a change in control. An adjustment to the conversion rate will be required as the result of payment of a cash dividend only if such adjustment would be greater than 1% (or at such time as the cumulative impact on the conversion rate reaches 1% in the aggregate). As of September 25, 2012, aggregate dividends of $0.08 per share would result in a cumulative change in the conversion rate of approximately 0.9%. At June 30, 2012 and September 30, 2011, the 2023 Notes had no capital in excess of par value component as substantially all of these notes were put to Griffon at par and settled in July 2010.

[7] In November 2010, Clopay Europe GMBH ("Clopay Europe") entered into a €10,000 revolving credit facility and a €20,000 term loan. The facility accrues interest at Euribor plus 2.1% per annum, and the term loan accrues interest at Euribor plus 2.2% per annum. The revolving facility matures in November 2012, but is renewable upon mutual agreement with the bank. In July 2011, the full €20,000 was drawn on the Term Loan, with a portion of the proceeds used to repay borrowings under the revolving credit facility. The term loan is payable in ten equal quarterly installments which began in September 2011, with maturity in December 2013. Under the term loan, Clopay Europe is required to maintain a certain minimum equity to assets ratio and keep leverage below a certain level, defined as the ratio of total debt to EBITDA. At June 30, 2012, there was €1,000 borrowed on the revolving credit with €9,000 available for borrowing.

[8] In February 2012, Clopay do Brazil, a subsidiary of Plastics, borrowed $4,000 at a rate of 104.5% of Brazilian CDI. The loan was used to refinance existing loans and is collateralized by accounts receivable and a 50% guaranty by Plastics and is to be repaid in four equal, semi-annual installments of principal plus accrued interest beginning in August 2012. Clopay do Brazil also maintains a line of credit of approximately $1,700. Interest on borrowings accrue at a rate of Brazilian CDI plus 6.0%. At June 30, 2012 there was approximately $1,346 borrowed under the line.

[9] In connection with the ATT acquisition, Clopay Ames True Temper Holding Corp. ("Clopay Ames"), a subsidiary of Griffon, entered into a $375,000 secured term Loan ("Term Loan") and a $125,000 asset based lending agreement ("ABL").On November 30, 2010, Clopay Ames, as required under the Term Loan agreement, entered into an interest rate swap on a notional amount of $200,000 of the Term Loan. The agreement fixed the LIBOR component of the Term Loan interest rate at 2.085% for the notional amount of the swap.On March 17, 2011, the Term Loan and swap were terminated, and on March 18, 2011, the ABL was terminated, in connection with the issuance of the Senior Notes and Credit Agreement.

[10] In March 2008, Telephonics entered into a credit agreement with JPMorgan Chase Bank, N.A., as administrative agent, and the lenders party thereto, pursuant to which the lenders agreed to provide a five-year, revolving credit facility of $100,000 (the "TCA"). The TCA terminated in connection with the Credit Agreement.