SHAREHOLDERS' EQUITY (Detail) (USD $)	3 Months Ended					9 Months Ended		12 Months Ended
	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2011
Common Stock, Dividends, Per Share, Cash Paid (in Dollars per share)	$ 0.02	$ 0.02	$ 0.02
Retained Earnings For Dividend Distributions	$ 1,190,000					$ 3,564,000
Dividends Payable, Amount Per Share (in Dollars per share)	$ 0.02					$ 0.02
Share-based Compensation Arrangement by Share-based Payment Award, Description						Options granted under the Incentive Plan may be either "incentive stock options" or nonqualified stock options, generally expire ten years after the date of grant and must be granted at an exercise price of not less than 100% of the fair market value at the date of grant.
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)	1,770,509					1,770,509
Unamortized Portion Of Original Fair Value Of Stock Vested					6,400,000
Share-based Compensation	2,691,000			2,120,000		7,599,000	6,767,000
Stock Repurchase Program, Authorized Amount								50,000,000
Stock Repurchased During Period, Shares (in Shares)			283,400
Stock Repurchased During Period, Value			2,351,000
Stock Repurchased During Period Per Share (in Dollars per share)	$ 7.95		$ 8.29
Stock Repurchased Shares Total (in Shares)	417,667					866,446
Stock Repurchased Value Total	3,320,000					6,980
Stock Repurchase Program Shares Repurchase Price Per Share (in Dollars per share)						$ 8.06
Stock Repurchase Program, Remaining Authorized Repurchase Amount						43,020,000
Subsequent Event [Member]
Stock Repurchased During Period, Shares (in Shares)	66,199
Stock Repurchased During Period, Value	560,000
Stock Repurchased During Period Per Share (in Dollars per share)	$ 8.47
Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)	3,000,000					3,000,000
Incentive Stock Options [Member]
Stock Issued During Period, Shares, New Issues (in Shares)						600,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)	2,000	110,000	309,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	19,000	1,119,000	2,881,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)	$ 9.33	$ 9.83	$ 9.31
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period One (in Shares)		82,500
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Two (in Shares)		27,500
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)		37,500	191,000		590,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value					$ 7,346,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)					$ 12.45
Description Of Performance Shares Vested					Prior to the change in the terms of the grant, the performance shares had a fair value of $7,346, or a weighted average fair value of $12.45 per share, and cliff vested when either Griffon's common stock closed at or above $16 per share for twenty consecutive trading days or 7 years from the date of grant, whichever came first. In January 2012, the terms of the grant were modified such that the price of Griffon common stock must close at or above $16 per share for thirty consecutive trading days on or prior to January 10, 2016 in order for the shares to vest; otherwise, the shares will be forfeited