NOTES PAYABLE, CAPITALIZED LEASES AND LONG-TERM DEBT (Details)	0 Months Ended	1 Months Ended				3 Months Ended	12 Months Ended										0 Months Ended				12 Months Ended					1 Months Ended	12 Months Ended								0 Months Ended		12 Months Ended											0 Months Ended	12 Months Ended							12 Months Ended							1 Months Ended	12 Months Ended				1 Months Ended							1 Months Ended	12 Months Ended							1 Months Ended		1 Months Ended		1 Months Ended		3 Months Ended
	Feb. 14, 2014	Jul. 31, 2014 USD ($)	Dec. 31, 2013 USD ($) loan	Nov. 30, 2012	Oct. 31, 2006 USD ($)	Mar. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2012 USD ($)	Oct. 21, 2013 property	Sep. 30, 2014 Northcote Holdings Pty. Ltd [Member] USD ($) line_of_credit	May 31, 2014 Northcote Holdings Pty. Ltd [Member] loan	Sep. 30, 2014 Revolver due 2019 [Member] USD ($)	Sep. 30, 2014 Letter Of Credit Subfacility [Member] Revolver due 2019 [Member] USD ($)	Feb. 14, 2014 Letter Of Credit Subfacility [Member] Revolver due 2019 [Member] USD ($)	Feb. 14, 2014 Multicurrency Subfacility [Member] Revolver due 2019 [Member] USD ($)	Feb. 14, 2014 Swingline Subfacility [Member] Revolver due 2019 [Member] USD ($)	Feb. 14, 2014 Margin Rate [Member] Revolver due 2019 [Member]	Feb. 14, 2014 LIBOR Rate [Member]	Dec. 21, 2009 Convert. debt due 2017 [Member]	Sep. 30, 2014 Convert. debt due 2017 [Member] USD ($)	Sep. 30, 2013 Convert. debt due 2017 [Member] USD ($)	Dec. 21, 2009 Convert. debt due 2017 [Member] USD ($)	Sep. 30, 2014 Convert. debt due 2017 [Member] Level 1 [Member] USD ($)	Sep. 30, 2014 ESOP Loans [Member] USD ($)	Oct. 31, 2006 Capital lease - real estate [Member] USD ($)	Sep. 30, 2014 Capital lease - real estate [Member] USD ($)		Sep. 30, 2013 Capital lease - real estate [Member] USD ($)		Sep. 30, 2012 Capital lease - real estate [Member]		Sep. 30, 2014 Senior notes [Member] Level 1 [Member] USD ($)	Feb. 27, 2014 Senior notes [Member] Senior note due 2022 [Member] USD ($)	Feb. 27, 2014 Senior notes [Member] Senior note due 2022 [Member] Senior notes due 2018 [Member] USD ($)	Feb. 27, 2014 Senior notes [Member] Senior note due 2022 [Member] Senior notes due 2018 [Member] USD ($)	Sep. 30, 2014 Senior notes due 2018 [Member] USD ($)		Sep. 30, 2013 Senior notes due 2018 [Member] USD ($)		Sep. 30, 2012 Senior notes due 2018 [Member]		Sep. 30, 2014 Revolver due 2019 [Member] USD ($)		Feb. 14, 2014 Revolver due 2019 [Member] USD ($)	Sep. 30, 2013 Revolver due 2019 [Member] USD ($)		Oct. 21, 2013 Real estate mortgages [Member]	Sep. 30, 2014 Real estate mortgages [Member] USD ($)		Sep. 30, 2013 Real estate mortgages [Member] USD ($)		Sep. 30, 2012 Real estate mortgages [Member]		Oct. 21, 2013 Real estate mortgages [Member] USD ($)	Sep. 30, 2014 ESOP Loans [Member] USD ($)		Sep. 30, 2013 ESOP Loans [Member] USD ($)		Sep. 30, 2012 ESOP Loans [Member]		Sep. 30, 2010 ESOP Loans [Member]	Nov. 30, 2010 Revolver due 2013 [Member] EUR (€)	Sep. 30, 2013 Revolver due 2013 [Member]		Sep. 30, 2012 Revolver due 2013 [Member]	Sep. 30, 2014 Revolver due 2013 [Member] USD ($)	Nov. 30, 2010 Term Loan [Member] EUR (€)	Dec. 31, 2013 Term Loan [Member] Northcote Holdings Pty. Ltd [Member] AUD	Sep. 30, 2014 Non U.S. term loans [Member] USD ($)		Sep. 30, 2013 Non U.S. term loans [Member] USD ($)		Sep. 30, 2014 Non U.S. term loans [Member] Brazilian CDI [Member]	Nov. 30, 2012 Non U.S. lines of credit [Member] CAD	Sep. 30, 2014 Non U.S. lines of credit [Member] CAD	Sep. 30, 2014 Non U.S. lines of credit [Member] USD ($)		Sep. 30, 2013 Non U.S. lines of credit [Member] USD ($)		Sep. 30, 2014 Non U.S. lines of credit [Member] LIBOR Rate [Member]	Sep. 30, 2014 Non U.S. lines of credit [Member] Bankers Acceptance Rate [Member]	Dec. 31, 2013 Non U.S. lines of credit [Member] Line of Credit One [Member] Northcote Holdings Pty. Ltd [Member]	Sep. 30, 2014 Non U.S. lines of credit [Member] Line of Credit One [Member] Northcote Holdings Pty. Ltd [Member] AUD	May 31, 2014 Non U.S. lines of credit [Member] Line of Credit Two [Member] Northcote Holdings Pty. Ltd [Member]	Sep. 30, 2014 Non U.S. lines of credit [Member] Line of Credit Two [Member] Northcote Holdings Pty. Ltd [Member] AUD	May 31, 2014 Term Loan May 2014 [Member] Northcote Holdings Pty. Ltd [Member] USD ($)	May 31, 2014 Term Loan May 2014 [Member] Northcote Holdings Pty. Ltd [Member] AUD	Dec. 31, 2013 Term Loan December 2013 and May 2014 [Member] Northcote Holdings Pty. Ltd [Member]	Sep. 30, 2014 Term Loan December 2013 and May 2014 [Member] Northcote Holdings Pty. Ltd [Member] USD ($)	Sep. 30, 2012 Convertible Debt 2023 [Member] USD ($)
NOTES PAYABLE, CAPITALIZED LEASES AND LONG-TERM DEBT (Details) [Line Items]
Debt instrument exercised period							5 years
Minimum payments under capital leases for 2015							$ 1,905,000
Minimum payments under capital leases for 2016							1,878,000
Minimum payments under capital leases for 2017							1,646,000
Minimum payments under capital leases for 2018							1,514,000
Minimum payments under capital leases for 2019							1,424,000
Minimum payments under capital leases thereafter							3,063,000
Capital leased assets, gross							16,446,000	15,304,000
Capital leases, lessee balance sheet, assets by major class, accumulated depreciation							6,755,000	5,460,000
Deferred interest charges							181,000	207,000
Capitalized leases interest rate minimum							5.00%
Capitalized leases interest rate maximum							10.00%
Capitalized leases maturity description							2015 through 2022
Amortization							1,579,000	1,605,000	1,598,000
Proceeds from issuance of debt							691,943,000	303,000	4,000,000																	14,290,000
Payments to acquire buildings					10,000,000
Capital lease maturity year					2022
Long-term debt, percentage bearing fixed interest, percentage rate					5.00%
Minimum payments under debt agreements for 2015							7,886,000
Minimum payments under debt agreements for 2016							33,332,000
Minimum payments under debt agreements for 2017							4,531,000
Minimum payments under debt agreements for 2018							104,442,000
Minimum payments under debt agreements for 2019							57,402,000
Minimum payments under debt agreements thereafter							614,978,000
Debt instrument, face amount			21,098,000																				100,000,000											600,000,000		550,000,000																			17,175,000														12,500,000																			20,000,000
Debt instrument, interest rate, stated percentage								4.00%	4.00%														4.00%											5.25%		7.125%	7.125%
Payment of tender offer premium							31,530,000																												31,530,000
Debt instrument, periodic payment, interest																																			16,716,000
Notes payable, fair value disclosure																								110,188,000									570,000,000
Underwriting fees and other expense capitalized							10,313,000
Loss from debt extinguishment						24,964,000	38,890,000	0	0																												38,890,000
Write off of deferred debt issuance cost							6,574,000
Prepaid interest on defeased note on extinguishment of debt							786,000
Line of credit facility, current borrowing capacity															60,000,000	50,000,000																													225,000,000																																							3,000,000		5,000,000
Proceeds from lines of credit																	30,000,000
Line of credit facility, interest rate during period																		1.25%	2.25%
Maximum percentage of equity interest of subsidiaries borrowings guaranteed	65.00%
Line of credit facility, amount outstanding							0				0		25,000,000	18,929,000																																																					0			3,306,000																				28,470,000
Line of credit facility, remaining borrowing capacity													181,071,000
Debt instrument, convertible, conversion ratio																					68.4571
Debt conversion, converted instrument, amount																					1,000
Debt instrument, convertible, conversion price (in Dollars per share)																					$ 14.61
Debt instrument, convertible, threshold percentage of stock price trigger																				1.00%
Last conversion price adjustment (in Dollars per share)																					$ 0.06
Potential conversion rate adjustment																					0.52%
Debt instrument, convertible, if-converted value in excess of principal																					15,720,000	15,720,000
Number of properties refinanced										2
Debt instrument, maturity date																																																Oct. 31, 2018
Debt instrument, description of variable rate basis																																																	LIBOR plus 2.75%													The loan bears interest at a) LIBOR plus 2.38% or b) the lender’s prime rate, at Griffon’s option.				The revolving credit facility accrues interest at EURIBOR plus 2.20% per annum.
Debt instrument, basis spread on variable rate				1.30%																																												2.75%								2.38%							2.20%																				2.25%		2.50%				2.80%
Long-term debt, gross							822,571,000	702,501,000																	38,946,000		8,551,000	[1]	9,529,000	[2]									550,000,000	[3]			25,000,000	[4]		0	[3]		16,388,000	[5]	13,212,000	[6]				38,946,000	[2]	21,098,000	[5]											28,470,000	[7]	3,115,000	[1]				3,306,000	[1]	4,606,000	[1]
Number of refinanced ESOP loan			2
Number of new term loan refinance from ESOP loans			1
Amount of line note available to purchase common stock in open market			10,000,000
Share based compensation arrangement by share based payment award shares purchased for award value		10,000,000
Debt instrument, periodic payment, principal																																																								506,000																															625,000
Debt instrument balloon payment																																																								30,137,000
Stock issued during period, shares, ESOP							1,591,117
Stock issued during period, value, ESOP							20,000,000
ESOP, weighted average purchase price of shares purchased (in Dollars per share)							$ 12.57
Proceeds from long-term lines of credit (in Euro)																																																															10,000,000					20,000,000							15,000,000	15,000,000
Maintains maximum amount of line of credit																																																																						5,200,000
Debt instrument, interest rate during period							6.00%																				5.30%	[2]	5.30%	[2]	5.30%	[2]					7.40%	[3]	7.40%	[3]	7.40%	[3]							3.90%	[6]	4.90%	[6]	4.00%	[6]		2.80%	[5]	2.90%	[5]	3.00%	[5]			0.50%	[1]
Line of credit facility, interest rate at period end																																																																										17.00%							1.53%	2.52%
Line of credit facility, interest rate description																																																																											The facility accrues interest at LIBOR (USD) or the Bankers Acceptance Rate (CDN) plus 1.3% per annum.
Debt instrument, number of loans											2	2
Debt instrument, interest rate at period end																											5.00%	[1]	5.00%	[2]									7.10%	[3]																																																		5.50%
Debt instrument, interest rate, effective percentage																																																																																				4.95%		5.20%
Convertible subordinated debt																																																																																											$ 532,000

[1] In November 2010, Clopay Europe GMBH (“Clopay Europe”) entered into a €10,000 revolving credit facility and a €20,000 term loan. The term loan was paid off in December 2013 and the revolver had no borrowings outstanding at September 30, 2014. The revolving facility matures in November 2014, but is renewable upon mutual agreement with the bank. The revolving credit facility accrues interest at EURIBOR plus 2.20% per annum. 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. Clopay do Brasil maintains lines of credit of approximately $5,200. Interest on borrowings accrues at a rate of Brazilian CDI plus 6.0% (17.00% at September 30, 2014). At September 30, 2014 there was approximately $3,306 borrowed under the lines. Clopay Plastic Products Company, Inc. guarantees the loan and lines.In November 2012, Garant G.P. (“Garant”) entered into a CAD $15,000 revolving credit facility. The facility accrues interest at LIBOR (USD) or the Bankers Acceptance Rate (CDN) plus 1.3% per annum (1.53% LIBOR USD and 2.52% Bankers Acceptance Rate CDN as of September 30, 2014). The revolving facility matures in November 2015. Garant is required to maintain a certain minimum equity. At September 30, 2014, there were no borrowings under the revolving credit facility with CAD $15,000 available for borrowing.

[2] In October 2006, CBP entered into a capital lease totaling $14,290 for real estate in Troy, Ohio. The lease matures in 2022, bears interest at a fixed rate of 5.0%, is secured by a mortgage on the real estate and is guaranteed by Griffon.

[3] On February 27, 2014, in an unregistered offering through a private placement under Rule 144A, Griffon issued, at par, $600,000 of 5.25% Senior Notes due in 2022 (“Senior Notes”); interest is payable semi-annually on March 1 and September 1, starting September 1, 2014. Proceeds from the Senior Notes were used to redeem $550,000 of 7.125% senior notes due 2018, to pay a call and tender offer premium of $31,530 and to make interest payments of $16,716, with the balance used to pay a portion of the related transaction fees and expenses. In connection with the issuance of the Senior Notes, all obligations under the $550,000 of 7.125% senior notes due in 2018 were discharged. The Senior Notes are senior unsecured obligations of Griffon guaranteed by certain domestic subsidiaries, and subject to certain covenants, limitations and restrictions. On June 18, 2014, Griffon exchanged all of the Senior Notes for substantially identical Senior Notes registered under the Securities Act of 1933 via an exchange offer. The fair value of Senior Notes approximated $570,000 on September 30, 2014 based upon quoted market prices (level 1 inputs).In connection with these transactions, Griffon capitalized $10,313 of underwriting fees and other expenses incurred related to the issuance and exchange of the Senior Notes, which will amortize over the term of such notes. Griffon recognized a loss on the early extinguishment of debt on the 7.125% senior notes aggregating $38,890, comprised of the $31,530 tender offer premium, the write-off of $6,574 of remaining deferred financing fees and $786 of prepaid interest on defeased notes. On February 14, 2014, Griffon amended its $225,000 Revolving Credit Facility (“Credit Agreement”) to extend its maturity from March 18, 2018 to March 28, 2019, and to amend certain financial maintenance and negative covenants to improve Griffon's financial and operating flexibility. The facility includes a letter of credit sub-facility with a limit of $60,000, 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, in each case without a floor, plus an applicable margin, which adjusts based on financial performance. Current margins are 1.25% for base rate loans and 2.25% for LIBOR loans. 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 negative covenants place limits on Griffon's ability to, among other things, incur indebtedness, incur liens and make restricted payments and investments. Borrowings under the Credit Agreement are guaranteed by Griffon’s material domestic subsidiaries and are secured, on a first priority basis, by substantially all domestic assets of the Company and the guarantors and a pledge of not greater than 65% of the equity interest in each of Griffon’s material, first-tier foreign subsidiaries (except that a lien on the assets of Griffon’s material domestic subsidiaries securing a limited amount of the debt under the credit agreement relating to Griffon's Employee Stock Ownership Plan ranks pari passu with the lien granted on such assets under the Credit Agreement; see footnote (d) below). At September 30, 2014, there were $18,929 of standby letters of credit outstanding under the Credit Agreement and $25,000 in outstanding borrowings; $181,071 was available for borrowing at that date.

[4] On December 21, 2009, Griffon issued $100,000 principal of 4% convertible subordinated notes due 2017 (the “2017 Notes”). The current conversion rate of the 2017 Notes is 68.4571 shares of Griffon’s common stock per $1 principal amount of notes, corresponding to a conversion price of $14.61 per share. 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 30, 2014, aggregate dividends since the last conversion price adjustment of $0.06 per share would have resulted in an adjustment to the conversion ratio of approximately 0.52%. At both September 30, 2014 and 2013, the 2017 Notes had a capital in excess of par component, net of tax, of $15,720. The fair value of the 2017 Notes approximated $110,188 on September 30, 2014 based upon quoted market prices (level 1 inputs).

[5] In December 2013, Griffon’s Employee Stock Ownership Plan (“ESOP”) entered into an agreement that refinanced the two existing ESOP loans into one new Term Loan in the amount of $21,098 (the "Agreement"). The Agreement also provided for a Line Note with $10,000 available to purchase shares of Griffon common stock in the open market. In July 2014, Griffon's ESOP entered into an amendment of the existing Agreement which provided an additional $10,000 Line Note available to purchase shares in the open market. During 2014, the Line Notes were combined with the Term Loan to form one new Term Loan. The Term Loan bears interest at LIBOR plus 2.38% or the lender’s prime rate, at Griffon’s option. The Term Loan requires quarterly principal payments of $506, with a balloon payment of approximately $30,137 due at maturity on December 31, 2018. During 2014, 1,591,117 shares of Griffon common stock, for a total of $20,000, or $12.57 per share, were purchased with proceeds from the Line Notes. At September 30, 2014, $38,946 was outstanding under the Term Loan. The Term Loan is secured by shares purchased with the proceeds of the loan and with a lien on a specific amount of Griffon assets (which lien ranks pari passu with the lien granted on such assets under the Credit Agreement) and is guaranteed by Griffon.

[6] On October 21, 2013, Griffon refinanced two real estate mortgages to secure loans totaling $17,175. The loans mature in October 2018, are collateralized by the related properties and are guaranteed by Griffon. The loans bear interest at a rate of LIBOR plus 2.75%. At September 30, 2014, $16,388 was outstanding.

[7] In December 2013 and May 2014, Northcote Holdings Pty Ltd entered into two unsecured term loans in the outstanding amounts of AUD $12,500 and AUD $20,000, respectively. The AUD $12,500 term loan requires quarterly interest payments with principal due upon maturity in December 2016. The AUD $20,000 term loan requires quarterly principal payments of $625 beginning in August 2015 with a balloon payment due upon maturity in May 2017. The loans accrue interest at Bank Bill Swap Bid Rate “BBSY” plus 2.8% per annum (5.5% at September 30, 2014 for each loan). As of September 30, 2014, Griffon had an outstanding combined balance of $28,470 on the term loans. Subsidiaries of Northcote Holdings Pty Ltd also maintain two lines of credit of AUD $3,000 and AUD $5,000 which accrue interest at BBSY plus 2.25% per annum (4.95% at September 30, 2014) and 2.50% per annum (5.20% at September 30, 2014), respectively. At September 30, 2014, there were no outstanding borrowings under the lines. Griffon Corporation guarantees the term loans and the AUD $3,000 line of credit; the assets of a subsidiary of Northcote Holdings Pty Ltd secures the AUD $5,000 line of credit.