EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Sep. 30, 2021

Retirement Benefits [Abstract]

Schedule of Net Benefit Costs

Net periodic costs (benefits) were as follows:

	Defined Benefits for the Years Ended  September 30,						Supplemental Benefits for the Years  Ended September 30,
	2021		2020		2019		2021		2020		2019
Net periodic (benefits) costs:
Interest cost	$	2,816	$	4,267	$	5,778	$	162	$	335	$	503
Expected return on plan assets	(10,177)		(10,343)		(10,331)		—		—		—
Amortization of:
Prior service costs	—		—		—		—		14		14
Actuarial loss	5,776		3,769		630		516		399		258
Total net periodic (benefits) costs	$	(1,585)	$	(2,307)	$	(3,923)	$	678	$	748	$	775

Schedule of Assumptions Used

The weighted-average assumptions used in determining the net periodic (benefits) costs were as follows:

	Defined Benefits for the Years Ended  September 30,						Supplemental Benefits for the Years  Ended September 30,
	2021		2020		2019		2021		2020		2019
Discount rate	2.30	%	2.92	%	4.10	%	1.69	%	2.64	%	3.99	%
Expected return on assets	6.75	%	7.00	%	7.00	%	—	%	—	%	—	%

Schedule of Plan Assets and Benefit Obligation of Defined Benefit Plan

Plan assets and benefit obligation of the defined and supplemental benefit plans were as follows:

	Defined Benefits at September 30,				Supplemental Benefits at September 30,
	2021		2020		2021		2020
Change in benefit obligation:
Benefit obligation at beginning of fiscal year	$	183,003	$	177,797	$	16,070	$	16,180
Interest cost	2,816		4,267		162		335
Benefits paid	(10,743)		(10,747)		(1,936)		(1,939)
Actuarial (gain) loss	(4,571)		11,686		479		1,494
Benefit obligation at end of fiscal year	170,505		183,003		14,775		16,070
Change in plan assets:
Fair value of plan assets at beginning of fiscal year	147,145		145,610		—		—
Actual return on plan assets	23,199		4,261		—		—
Company contributions	922		8,021		1,936		1,939
Benefits paid	(10,743)		(10,747)		(1,936)		(1,939)
Fair value of plan assets at end of fiscal year	160,523		147,145		—		—
Projected benefit obligation in excess of plan assets	$	(9,982)	$	(35,858)	$	(14,775)	$	(16,070)
Amounts recognized in the statement of financial position consist of:
Accrued liabilities	$	—	$	—	$	(1,884)	$	(1,891)
Other liabilities (long-term)	(9,982)		(35,858)		(12,890)		(14,179)
Total Liabilities	(9,982)		(35,858)		(14,774)		(16,070)
Net actuarial losses	38,296		61,666		7,662		7,700
Prior service cost	—		—		—		—
Deferred taxes	(8,042)		(12,950)		(1,609)		(1,617)
Total Accumulated other comprehensive loss, net of tax	30,254		48,716		6,053		6,083
Net amount recognized at September 30,	$	20,272	$	12,858	$	(8,721)	$	(9,987)
Accumulated benefit obligations	$	170,505	$	183,003	$	14,775	$	16,070
Information for plans with accumulated benefit obligations in excess of plan assets:
ABO	$	170,505	$	183,003	$	14,775	$	16,070
PBO	170,505		183,003		14,775		16,070
Fair value of plan assets	160,523		147,145		—		—

Schedule of Weighted Average Assumptions Used in Defined and Supplemental Benefit Obligations

The weighted-average assumptions used in determining the benefit obligations were as follows:

	Defined Benefits at  September 30,				Supplemental Benefits at  September 30,
	2021		2020		2021		2020
Weighted average discount rate	2.58	%	2.30	%	1.94	%	1.69	%

Schedule of Expected Benefit Payments

Estimated future benefit payments to retirees, which reflect expected future service, are as follows:

For the years ending September 30,	Defined Benefits		Supplemental Benefits
2022	$	10,909	$	1,884
2023	10,902		1,765
2024	10,876		1,641
2025	10,803		1,513
2026	10,789		1,383
2027 through 2031	51,669		4,965

Schedule of Actual and Weighted Average Assets Allocation for Qualified Benefit Plans

The actual and weighted-average asset allocation for qualified benefit plans were as follows:

	At September 30,
	2021		2020		Target
Cash and equivalents	1.2	%	0.4	%	—	%
Equity securities	52.5	%	48.5	%	63.0	%
Fixed income	26.9	%	31.9	%	37.0	%
Other	19.4	%	19.2	%	—	%
Total	100.0	%	100.0	%	100.0	%

Schedule of Fair Value of Pension and Postretirement Plan Assets by Asset Category

The following table presents the fair values of Griffon’s pension and post-retirement plan assets by asset category:

At September 30, 2021	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Cash and equivalents	$	1,867	$	—	$	—	$	1,867
Government agency securities	32,217		4,608		—		36,825
Debt instruments	1,063		2,706		—		3,769
Equity securities	84,129		—		—		84,129
Commingled funds	—		—		11,286		11,286
Limited partnerships and hedge fund investments	—		19,823		—		19,823
Other Securities	2,379		160		—		2,539
Subtotal	$	121,655	$	27,297	$	11,286	$	160,238
Accrued income and plan receivables							285
Total							$	160,523

At September 30, 2020	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Cash and equivalents	$	600	$	—	$	—	$	600
Government and agency securities	33,675		6,136		—		39,811
Debt instruments	179		2,722		—		2,901
Equity securities	68,987		—		—		68,987
Commingled funds	—		—		9,362		9,362
Limited partnerships and hedge fund investments	—		17,867		—		17,867
Other Securities	2,488		163		—		2,651
Subtotal	$	105,929	$	26,888	$	9,362	$	142,179
Accrued income and plan receivables							4,966
Total							$	147,145

The following table represents level 3 significant unobservable inputs for the years ended September 30, 2021 and 2020:

	Significant Unobservable Inputs (Level 3)
As of October 1, 2020	$	8,776
Purchases, issuances and settlements	—
Gains and losses	586
As of September 30, 2020	9,362
Purchases, issuances and settlements	—
Gains and losses	1,924
As of September 30, 2021	$	11,286

Employee Stock Ownership Plan (ESOP) Disclosures

The ESOP shares were as follows:

	At September 30,
	2021	2020
Allocated shares	3,322,355	3,301,448
Unallocated shares	1,852,492	2,058,187
Total	5,174,847	5,359,635