SHAREHOLDERS' EQUITY	9 Months Ended
Jun. 30, 2018
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY During 2018, the Company paid a quarterly cash dividend of $0.07 per share in each quarter and a special cash dividend of $1.00 paid in the third quarter, totaling $1.21 per share for the nine months ended June 30, 2018. During 2017, the Company paid quarterly cash dividends of $0.06 per share, totaling $0.24 per share for the year. Dividends paid on shares in the ESOP were used to offset ESOP loan payments and recorded as a reduction of debt service payments and compensation expense. A dividend payable was established for the holders of restricted shares; such dividends will be released upon vesting of the underlying restricted shares. On August 1, 2018, the Board of Directors declared a quarterly cash dividend of $0.07 per share, payable on September 20, 2018 to shareholders of record as of the close of business on August 23, 2018. Compensation expense for restricted stock is recognized ratably over the required service period based on the fair value of the grant, calculated as the number of shares granted multiplied by the stock price on the date of grant and, for performance shares, the likelihood of achieving the performance criteria. Compensation cost related to stock-based awards with graded vesting, generally over a period of three to four years, is recognized using the straight-line attribution method and recorded within SG&A expenses. On January 29, 2016, shareholders approved the Griffon Corporation 2016 Equity Incentive Plan ("Incentive Plan") under which awards of performance shares, performance units, stock options, stock appreciation rights, restricted shares, restricted stock units, deferred shares and other stock-based awards may be granted. On January 31, 2018, shareholders approved Amendment No. 1 to the Incentive Plan pursuant to which, among other things, 1,000,000 shares were added to the Incentive Plan. 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 are granted at an exercise price of not less than 100% of the fair market value at the date of grant. The maximum number of shares of common stock available for award under the Incentive Plan is 3,350,000 (600,000 of which may be issued as incentive stock options), plus (i) any shares reserved for issuance under the 2011 Equity Incentive Plan as of the effective date of the Incentive Plan, and (ii) any shares underlying awards outstanding on such effective date under the 2011 Incentive Plan that are canceled or forfeited. As of June 30, 2018, there were 1,200,755 shares available for grant. All grants outstanding under former equity plans will continue under their terms; no additional awards will be granted under such plans. During the first quarter of 2018, Griffon granted 1,008,756 shares of restricted stock and restricted stock units. This included 480,756 shares of restricted stock and restricted stock units, subject to certain performance conditions, with vesting periods of three years, with a total fair value of $9,980, or a weighted average fair value of $20.76 per share. This also included 528,000 shares of restricted stock granted to two senior executives with a vesting period of four years and a two year post-vesting holding period, subject to the achievement of certain absolute and relative performance conditions relating to the price of Griffon's common stock. So long as the minimum performance condition is attained, the amount of shares that can vest will range from 384,000 to 528,000. The total fair value of these restricted shares is approximately $7,008, or a weighted average fair value of $13.27. Also, during the second quarter, Griffon granted 250,170 shares with a vesting period of three years and a fair value of $4,739, or a weighted average fair value of $18.94 per share. During the third quarter of 2018, no grants were issued. For the quarters ended June 30, 2018 and 2017, stock based compensation expense totaled $2,452 and $2,405, respectively. For the nine months ended June 30, 2018 and 2017, such expense totaled $7,372 and $7,200, respectively. During the quarter and nine months ended June 30, 2018, 1,592 shares, with a market value of $33 or $20.85 per share, and 199,044 shares, with a market value of $4,478 or $22.50 per share, respectively, were withheld to settle employee taxes due to the vesting of restricted stock, and were added to treasury. On December 21, 2009, Griffon issued $100,000 principal amount of 4% convertible subordinated notes due 2017 (the “2017 Notes”). On July 14, 2016, Griffon announced that it would settle, upon conversion, up to $125,000 of the conversion value of the 2017 Notes in cash, with amounts in excess of $125,000, if any, to be settled in shares of Griffon common stock. On January 17, 2017, Griffon settled the convertible debt for $173,855 with $125,000 in cash, utilizing borrowing under the Credit Agreement, and $48,858, or 1,954,993 shares of common stock issued from treasury. On August 3, 2016, Griffon’s Board of Directors authorized the repurchase of up to $50,000 of Griffon’s outstanding common stock. Under this share repurchase program, the Company may purchase shares in the open market, including pursuant to a 10b5-1 plan, or in privately negotiated transactions. During the quarter and nine months ended June 30, 2018, Griffon purchased 650,500 and 2,088,739 shares, respectively, of common stock under the August 2016 program, for a total of $12,694 and $41,110, respectively, or $19.51 and $19.68, respectively. As of June 30, 2018, $8,327 remains under the August 3, 2016 Board authorization. On August 1, 2018, Griffon's Board of Directors authorized the repurchase of an additional $50,000 of Griffon's outstanding common stock. From August 2011 through June 30, 2018, Griffon repurchased 22,518,037 shares of its common stock, for a total of $302,730 or $13.44 per share. This included the repurchase of 18,073,593 shares on the open market under Griffon's Board of Directors authorized repurchase programs for a total of $252,730 or $13.98 per shares, as well as the December 10, 2013 repurchase of 4,444,444 shares from GS Direct for $50,000, or $11.25 per share. On June 19, 2018, GS Direct completed an underwritten secondary offering to sell 5,583,375 shares of Griffon’s common stock, inclusive of the underwriters’ 30-day option to purchase additional shares. Following the closing of the offering, GS Direct no longer owns any shares of Griffon. GS Direct's initial 10,000,000 share investment was in 2008.

SHAREHOLDERS’ EQUITY

During 2018, the Company paid a quarterly cash dividend of $0.07 per share in each quarter and a special cash dividend of $1.00 paid in the third quarter, totaling $1.21 per share for the nine months ended June 30, 2018. During 2017, the Company paid quarterly cash dividends of $0.06 per share, totaling $0.24 per share for the year. Dividends paid on shares in the ESOP were used to offset ESOP loan payments and recorded as a reduction of debt service payments and compensation expense. A dividend payable was established for the holders of restricted shares; such dividends will be released upon vesting of the underlying restricted shares.

On August 1, 2018, the Board of Directors declared a quarterly cash dividend of $0.07 per share, payable on September 20, 2018 to shareholders of record as of the close of business on August 23, 2018.

Compensation expense for restricted stock is recognized ratably over the required service period based on the fair value of the grant, calculated as the number of shares granted multiplied by the stock price on the date of grant and, for performance shares, the likelihood of achieving the performance criteria. Compensation cost related to stock-based awards with graded vesting, generally over a period of three to four years, is recognized using the straight-line attribution method and recorded within SG&A expenses.

On January 29, 2016, shareholders approved the Griffon Corporation 2016 Equity Incentive Plan ("Incentive Plan") under which awards of performance shares, performance units, stock options, stock appreciation rights, restricted shares, restricted stock units, deferred shares and other stock-based awards may be granted. On January 31, 2018, shareholders approved Amendment No. 1 to the Incentive Plan pursuant to which, among other things, 1,000,000 shares were added to the Incentive Plan. 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 are granted at an exercise price of not less than 100% of the fair market value at the date of grant. The maximum number of shares of common stock available for award under the Incentive Plan is 3,350,000 (600,000 of which may be issued as incentive stock options), plus (i) any shares reserved for issuance under the 2011 Equity Incentive Plan as of the effective date of the Incentive Plan, and (ii) any shares underlying awards outstanding on such effective date under the 2011 Incentive Plan that are canceled or forfeited. As of June 30, 2018, there were 1,200,755 shares available for grant.

All grants outstanding under former equity plans will continue under their terms; no additional awards will be granted under such plans.

During the first quarter of 2018, Griffon granted 1,008,756 shares of restricted stock and restricted stock units. This included 480,756 shares of restricted stock and restricted stock units, subject to certain performance conditions, with vesting periods of three years, with a total fair value of $9,980, or a weighted average fair value of $20.76 per share. This also included 528,000 shares of restricted stock granted to two senior executives with a vesting period of four years and a two year post-vesting holding period, subject to the achievement of certain absolute and relative performance conditions relating to the price of Griffon's common stock. So long as the minimum performance condition is attained, the amount of shares that can vest will range from 384,000 to 528,000. The total fair value of these restricted shares is approximately $7,008, or a weighted average fair value of $13.27. Also, during the second quarter, Griffon granted 250,170 shares with a vesting period of three years and a fair value of $4,739, or a weighted average fair value of $18.94 per share. During the third quarter of 2018, no grants were issued.

For the quarters ended June 30, 2018 and 2017, stock based compensation expense totaled $2,452 and $2,405, respectively. For the nine months ended June 30, 2018 and 2017, such expense totaled $7,372 and $7,200, respectively.

During the quarter and nine months ended June 30, 2018, 1,592 shares, with a market value of $33 or $20.85 per share, and 199,044 shares, with a market value of $4,478 or $22.50 per share, respectively, were withheld to settle employee taxes due to the vesting of restricted stock, and were added to treasury.

On December 21, 2009, Griffon issued $100,000 principal amount of 4% convertible subordinated notes due 2017 (the “2017 Notes”). On July 14, 2016, Griffon announced that it would settle, upon conversion, up to $125,000 of the conversion value of the 2017 Notes in cash, with amounts in excess of $125,000, if any, to be settled in shares of Griffon common stock. On January 17, 2017, Griffon settled the convertible debt for $173,855 with $125,000 in cash, utilizing borrowing under the Credit Agreement, and $48,858, or 1,954,993 shares of common stock issued from treasury.

On August 3, 2016, Griffon’s Board of Directors authorized the repurchase of up to $50,000 of Griffon’s outstanding common stock. Under this share repurchase program, the Company may purchase shares in the open market, including pursuant to a 10b5-1 plan, or in privately negotiated transactions. During the quarter and nine months ended June 30, 2018, Griffon purchased 650,500 and 2,088,739 shares, respectively, of common stock under the August 2016 program, for a total of $12,694 and $41,110, respectively, or $19.51 and $19.68, respectively. As of June 30, 2018, $8,327 remains under the August 3, 2016 Board authorization. On August 1, 2018, Griffon's Board of Directors authorized the repurchase of an additional $50,000 of Griffon's outstanding common stock.

From August 2011 through June 30, 2018, Griffon repurchased 22,518,037 shares of its common stock, for a total of $302,730 or $13.44 per share. This included the repurchase of 18,073,593 shares on the open market under Griffon's Board of Directors authorized repurchase programs for a total of $252,730 or $13.98 per shares, as well as the December 10, 2013 repurchase of 4,444,444 shares from GS Direct for $50,000, or $11.25 per share.

On June 19, 2018, GS Direct completed an underwritten secondary offering to sell 5,583,375 shares of Griffon’s common stock, inclusive of the underwriters’ 30-day option to purchase additional shares. Following the closing of the offering, GS Direct no longer owns any shares of Griffon. GS Direct's initial 10,000,000 share investment was in 2008.