Griffon (GFF) 10-Q 30 Apr 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page	6 Months Ended
	Mar. 31, 2021shares
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-06620
Entity Registrant Name	GRIFFON CORPORATION
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	11-1893410
Entity Address, Address Line One	712 Fifth Ave, 18th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10019
City Area Code	212
Local Phone Number	957-5000
Title of 12(b) Security	Common Stock, $0.25 par value
Trading Symbol	GFF
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	56,683,519
Current Fiscal Year End Date	--09-30
Amendment Flag	false
Entity Central Index Key	0000050725
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
CURRENT ASSETS
Cash and equivalents	$ 175,564	$ 218,089
Accounts receivable, net of allowances of $9,594 and $8,505	399,193	340,546
Contract assets, net of progress payments of $20,449 and $24,175	75,000	84,426
Inventories	484,753	413,825
Prepaid and other current assets	55,705	46,897
Assets of discontinued operations	1,525	2,091
Total Current Assets	1,191,740	1,105,874
PROPERTY, PLANT AND EQUIPMENT, net	341,005	343,964
OPERATING LEASE RIGHT-OF-USE ASSETS	154,929	161,627
GOODWILL	446,365	442,643
INTANGIBLE ASSETS, net	357,506	355,028
OTHER ASSETS	27,440	32,897
ASSETS OF DISCONTINUED OPERATIONS	5,295	6,406
Total Assets	2,524,280	2,448,439
CURRENT LIABILITIES
Notes payable and current portion of long-term debt	14,913	9,922
Accounts payable	257,286	232,107
Accrued liabilities	151,091	163,994
Current portion of operating lease liabilities	30,685	31,848
Liabilities of discontinued operations	4,600	3,797
Total Current Liabilities	458,575	441,668
LONG-TERM DEBT, net	1,043,859	1,037,042
LONG-TERM OPERATING LEASE LIABILITIES	128,714	136,054
OTHER LIABILITIES	122,286	126,510
LIABILITIES OF DISCONTINUED OPERATIONS	6,415	7,014
Total Liabilities	1,759,849	1,748,288
COMMITMENTS AND CONTINGENCIES - See Note 22
SHAREHOLDERS’ EQUITY
Total Shareholders’ Equity	764,431	700,151
Total Liabilities and Shareholders’ Equity	$ 2,524,280	$ 2,448,439

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Statement of Financial Position [Abstract]
Accounts receivable, net allowances	$ 9,594	$ 8,505
Contract costs, net of progress payments	$ 20,449	$ 24,175

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	COMMON STOCK	CAPITAL IN EXCESS OF PAR VALUE	RETAINED EARNINGS	TREASURY SHARES	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	DEFERRED COMPENSATION
Balance (in shares) at Sep. 30, 2019		82,775			35,969
Balance at Sep. 30, 2019	$ 477,763	$ 20,694	$ 519,017	$ 568,516	$ (536,308)	$ (65,916)	$ (28,240)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	10,612			10,612
Dividend	(3,392)			(3,392)
Shares withheld on employee taxes on vested equity awards (in shares)					80
Shares withheld on employee taxes on vested equity awards	(1,758)				$ (1,758)
Amortization of deferred compensation	629						629
Equity awards granted, net (in shares)		182
Equity awards granted, net	0	$ 45	(45)
ESOP allocation of common stock	609		609
Stock-based compensation	3,150		3,150
Stock-based consideration	239		239
Other comprehensive income, net of tax	6,841					6,841
Balance (in shares) at Dec. 31, 2019		82,957			36,049
Balance at Dec. 31, 2019	494,693	$ 20,739	522,970	575,736	$ (538,066)	(59,075)	(27,611)
Balance (in shares) at Sep. 30, 2019		82,775			35,969
Balance at Sep. 30, 2019	477,763	$ 20,694	519,017	568,516	$ (536,308)	(65,916)	(28,240)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,507
Other comprehensive income, net of tax	(7,993)
Balance (in shares) at Mar. 31, 2020		83,741			36,310
Balance at Mar. 31, 2020	476,454	$ 20,935	526,988	573,209	$ (543,787)	(73,909)	(26,982)
Balance (in shares) at Dec. 31, 2019		82,957			36,049
Balance at Dec. 31, 2019	494,693	$ 20,739	522,970	575,736	$ (538,066)	(59,075)	(27,611)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	895			895
Dividend	(3,422)			(3,422)
Shares withheld on employee taxes on vested equity awards (in shares)					261
Shares withheld on employee taxes on vested equity awards	(5,721)				$ (5,721)
Amortization of deferred compensation	629						629
Equity awards granted, net (in shares)		784
Equity awards granted, net	0	$ 196	(196)
ESOP allocation of common stock	435		435
Stock-based compensation	3,662		3,662
Stock-based consideration	117		117
Other comprehensive income, net of tax	(14,834)					(14,834)
Balance (in shares) at Mar. 31, 2020		83,741			36,310
Balance at Mar. 31, 2020	476,454	$ 20,935	526,988	573,209	$ (543,787)	(73,909)	(26,982)
Balance (in shares) at Sep. 30, 2020		83,739			27,610
Balance at Sep. 30, 2020	700,151	$ 20,935	583,008	607,518	$ (413,493)	(72,092)	(25,725)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	29,500			29,500
Dividend	(4,469)			(4,469)
Shares withheld on employee taxes on vested equity awards (in shares)					133
Shares withheld on employee taxes on vested equity awards	(2,909)				$ (2,909)
Amortization of deferred compensation	609						609
Equity awards granted, net (in shares)		494
Equity awards granted, net	0	$ 123	(123)
ESOP allocation of common stock	596		596
Stock-based compensation	3,428		3,428
Other comprehensive income, net of tax	13,141					13,141
Balance (in shares) at Dec. 31, 2020		84,233			27,743
Balance at Dec. 31, 2020	740,047	$ 21,058	586,909	632,549	$ (416,402)	(58,951)	(25,116)
Balance (in shares) at Sep. 30, 2020		83,739			27,610
Balance at Sep. 30, 2020	700,151	$ 20,935	583,008	607,518	$ (413,493)	(72,092)	(25,725)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46,612
Other comprehensive income, net of tax	17,916
Balance (in shares) at Mar. 31, 2021		84,427			27,743
Balance at Mar. 31, 2021	764,431	$ 21,106	591,966	646,444	$ (416,402)	(54,176)	(24,507)
Balance (in shares) at Dec. 31, 2020		84,233			27,743
Balance at Dec. 31, 2020	740,047	$ 21,058	586,909	632,549	$ (416,402)	(58,951)	(25,116)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,112			17,112
Dividend	(3,217)			(3,217)
Amortization of deferred compensation	609						609
Equity awards granted, net (in shares)		194
Equity awards granted, net	0	$ 48	(48)
ESOP allocation of common stock	756		756
Stock-based compensation	4,349		4,349
Other comprehensive income, net of tax	4,775					4,775
Balance (in shares) at Mar. 31, 2021		84,427			27,743
Balance at Mar. 31, 2021	$ 764,431	$ 21,106	$ 591,966	$ 646,444	$ (416,402)	$ (54,176)	$ (24,507)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 634,832	$ 566,350	$ 1,244,123	$ 1,114,788
Cost of goods and services	464,516	414,318	903,635	812,835
Gross profit	170,316	152,032	340,488	301,953
Selling, general and administrative expenses	126,827	126,467	248,384	244,265
Income from operations	43,489	25,565	92,104	57,688
Other income (expense)
Interest expense	(15,831)	(16,871)	(31,521)	(33,082)
Interest income	304	310	349	571
Gain (adjustment) on sale of business	(949)	0	5,291	0
Loss from debt extinguishment, net	0	(6,690)	0	(6,690)
Other, net	847	615	806	1,393
Total other expense, net	(15,629)	(22,636)	(25,075)	(37,808)
Income before taxes	27,860	2,929	67,029	19,880
Provision for income taxes	10,748	2,034	20,417	8,373
Net income	$ 17,112	$ 895	$ 46,612	$ 11,507
Basic earnings per common share (in dollars per share)	$ 0.34	$ 0.02	$ 0.92	$ 0.28
Basic weighted-average shares outstanding (in shares)	50,838	41,565	50,717	41,369
Diluted earnings per common share (in dollars per share)	$ 0.32	$ 0.02	$ 0.88	$ 0.26
Diluted weighted-average shares outstanding (in shares)	53,264	43,734	53,211	43,826
Dividends paid per common share (in dollars per share)	$ 0.08	$ 0.075	$ 0.16	$ 0.15
Other comprehensive income (loss), net of taxes:
Foreign currency translation adjustments	$ 1,739	$ (16,471)	$ 13,862	$ (10,001)
Pension and other post retirement plans	1,245	669	2,951	1,341
Change in cash flow hedges	1,791	968	1,103	667
Total other comprehensive income (loss), net of taxes	4,775	(14,834)	17,916	(7,993)
Comprehensive income, net	$ 21,887	$ (13,939)	$ 64,528	$ 3,514

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 46,612	$ 11,507
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	31,149	31,544
Stock-based compensation	9,501	8,302
Asset impairment charges - restructuring	8,291	4,692
Provision for losses on accounts receivable	194	596
Amortization of debt discounts and issuance costs	1,349	2,267
Loss from debt extinguishment, net	0	6,690
Deferred income taxes	2,334	408
Loss (gain) on sale of assets and investments	151	(274)
Gain on sale of business	(5,291)	0
Change in assets and liabilities, net of assets and liabilities acquired:
Increase in accounts receivable and contract assets, net	(47,146)	(61,815)
Increase in inventories	(74,186)	(21,262)
(Increase) decrease in prepaid and other assets	271	(6,005)
Increase (decrease) in accounts payable, accrued liabilities, income taxes payable and operating lease liabilities	(1,470)	(38,053)
Other changes, net	2,400	560
Net cash used in operating activities	(25,841)	(60,843)
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of property, plant and equipment	(23,986)	(22,519)
Acquired businesses, net of cash acquired	(2,242)	(10,531)
Proceeds from sale of business, net	14,725	0
Investment purchases	(2,138)	0
Proceeds from the sale of property, plant and equipment	82	290
Other, net	27	0
Net cash used in investing activities	(13,532)	(32,760)
CASH FLOWS FROM FINANCING ACTIVITIES:
Dividends paid	(8,678)	(7,349)
Purchase of shares for treasury	(2,909)	(7,479)
Proceeds from long-term debt	14,029	1,061,343
Payments of long-term debt	(7,573)	(939,071)
Financing costs	(571)	(13,176)
Other, net	(214)	83
Net cash provided by (used in) financing activities	(5,916)	94,351
CASH FLOWS FROM DISCONTINUED OPERATIONS:
Net cash used in operating activities	(1,512)	(1,994)
Net cash provided by investing activities	2,749	0
Net cash provided by (used in) discontinued operations	1,237	(1,994)
Effect of exchange rate changes on cash and equivalents	1,527	(2,107)
NET DECREASE IN CASH AND EQUIVALENTS	(42,525)	(3,353)
CASH AND EQUIVALENTS AT BEGINNING OF PERIOD	218,089	72,377
CASH AND EQUIVALENTS AT END OF PERIOD	$ 175,564	$ 69,024

DESCRIPTION OF BUSINESS AND BAS

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	6 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION	DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION About Griffon Corporation Griffon Corporation (the “Company”, “Griffon”, "we" or "us") is a diversified management and holding company that conducts business through wholly-owned subsidiaries. Griffon oversees the operations of its subsidiaries, allocates resources among them and manages their capital structures. Griffon provides direction and assistance to its subsidiaries in connection with acquisition and growth opportunities as well as in connection with divestitures. In order to further diversify, Griffon also seeks out, evaluates and, when appropriate, will acquire additional businesses that offer potentially attractive returns on capital. The Company was founded in 1959, is a Delaware corporation headquartered in New York, N.Y. and is listed on the New York Stock Exchange (NYSE:GFF). Griffon currently conducts its operations through three reportable segments: • Consumer and Professional Products ("CPP") conducts its operations through The AMES Companies, Inc. ("AMES"). Founded in 1774, AMES is the leading North American manufacturer and a global provider of branded consumer and professional tools and products for home storage and organization, landscaping, and enhancing outdoor lifestyles. CPP sells products globally through a portfolio of leading brands including True Temper, AMES, and ClosetMaid. • Home and Building Products ("HBP") conducts its operations through Clopay Corporation ("Clopay"). Founded in 1964, Clopay is the largest manufacturer and marketer of garage doors and rolling steel doors in North America. Residential and commercial sectional garage doors are sold through professional dealers and leading home center retail chains throughout North America under the brands Clopay, Ideal, and Holmes. Rolling steel door and grille products designed for commercial, industrial, institutional, and retail use are sold under the CornellCookson brand. • Defense Electronics ("DE") conducts its operations through Telephonics Corporation ("Telephonics"), founded in 1933, a globally recognized leading provider of highly sophisticated intelligence, surveillance and communications solutions for defense, aerospace and commercial customers. In March 2020, the World Health Organization declared the outbreak of COVID-19 a pandemic, which continues to spread throughout the U.S. and the world. The impact from the rapidly changing U.S. and global market and economic conditions due to the COVID-19 outbreak is uncertain, with disruptions to the business of our customers and suppliers, which could impact our business and consolidated results of operations and financial condition in the future. While we have not incurred significant disruptions to our manufacturing or to our supply chain thus far from the COVID-19 outbreak, we are unable to accurately predict the impact COVID-19 will have due to numerous uncertainties, including the severity of the disease, the duration of the outbreak, actions that may be taken by governmental authorities, the impact to our customers’ and suppliers’ businesses and other factors identified in Part II, Item 1A “Risk Factors” in this Form 10-Q. We will continue to evaluate the nature and extent of the impact to our business, consolidated results of operations, and financial condition. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) for interim financial information, and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, these financial statements do not include all the information and footnotes required by US GAAP for complete financial statements. As such, they should be read together with Griffon’s Annual Report on Form 10-K for the year ended September 30, 2020, which provides a more complete explanation of Griffon’s accounting policies, financial position, operating results, business, properties and other matters. In the opinion of management, these financial statements reflect all adjustments considered necessary for a fair statement of interim results. Griffon’s CPP operations are seasonal; for this and other reasons, the financial results of the Company for any interim period are not necessarily indicative of the results for the full year. The condensed consolidated balance sheet information at September 30, 2020 was derived from the audited financial statements included in Griffon’s Annual Report on Form 10-K for the year ended September 30, 2020. The condensed consolidated financial statements include the accounts of Griffon and all subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting periods. These estimates may be adjusted due to changes in economic, industry or customer financial conditions, as well as changes in technology or demand. Significant estimates include allowances for doubtful accounts receivable and returns, net realizable value of inventories, restructuring reserves, valuation of goodwill and intangible assets, sales, profits and loss recognition for performance obligations satisfied over time, assumptions associated with pension benefit obligations and income or expenses, useful lives associated with depreciation and amortization of intangible and fixed assets, warranty reserves, sales incentive accruals, assumption associated with stock based compensation valuation, income taxes and tax valuation reserves, environmental reserves, legal reserves, insurance reserves, the valuation of assets and liabilities of discontinued operations, assumptions associated with valuation of acquired assets and assumed liabilities of acquired companies and the accompanying disclosures. These estimates are based on management’s best knowledge of current events and actions Griffon may undertake in the future. Actual results may ultimately differ from these estimates. Certain amounts in the prior year have been reclassified to conform to current year presentation.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The carrying values of cash and equivalents, accounts receivable, accounts and notes payable, and revolving credit and variable interest rate debt approximate fair value due to either the short-term nature of such instruments or the fact that the interest rate of the revolving credit and variable rate debt is based upon current market rates. Applicable accounting guidance establishes a fair value hierarchy requiring the Company to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the hierarchy is based on the lowest level of input that is significant to the fair value measurement. The accounting guidance establishes three levels of inputs that may be used to measure fair value, as follows: • Level 1 inputs are measured and recorded at fair value based upon quoted prices in active markets for identical assets. • Level 2 inputs include inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities. • Level 3 inputs are unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. The fair values of Griffon’s 2028 senior notes approximated $1,060,000 on March 31, 2021. Fair values were based upon quoted market prices (level 1 inputs). Insurance contracts with values of $3,821 at March 31, 2021 are measured and recorded at fair value based upon quoted prices in active markets for similar assets (level 2 inputs) and are included in Prepaid and other current assets on the Consolidated Balance Sheets. Items Measured at Fair Value on a Recurring Basis At March 31, 2021, trading securities, measured at fair value based on quoted prices in active markets for similar assets (level 2 inputs), with a fair value of $2,088 ($1,000 cost basis), were included in Prepaid and other current assets on the Consolidated Balance Sheets. Realized and unrealized gains and losses on trading securities are included in Other income in the Consolidated Statements of Operations and Comprehensive Income (Loss). In the normal course of business, Griffon’s operations are exposed to the effects of changes in foreign currency exchange rates. To manage these risks, Griffon may enter into various derivative contracts such as foreign currency exchange contracts, including forwards and options. As of March 31, 2021, Griffon entered into several such contracts in order to lock into a foreign currency rate for planned settlements of trade and inter-company liabilities payable in US dollars. At March 31, 2021, Griffon had $61,000 of Australian dollar contracts at a weighted average rate of $1.29 which qualified for hedge accounting (level 2 inputs). These hedges were all deemed effective as cash flow hedges with gains and losses related to changes in fair value deferred and recorded in Accumulated other comprehensive income (loss) ("AOCI") and Prepaid and other current assets, or Accrued liabilities, until settlement. Upon settlement, gains and losses are recognized in the Consolidated Statements of Operations and Comprehensive Income (Loss) in Cost of goods and services ("COGS"). AOCI included deferred losses of $831 ($582, net of tax) at March 31, 2021. Upon settlement, losses of $1,741 and $2,399 were recorded in COGS during the three and six months ended March 31, 2021, respectively. All contracts expire in 30 to 180 days. At March 31, 2021, Griffon had $7,935 of Canadian dollar contracts at a weighted average rate of $1.30. The contracts, which protect Canadian operations from currency fluctuations for US dollar based purchases, do not qualify for hedge accounting. For the three and six months ended March 31, 2021, fair value gains of $520 and $244, respectively, were recorded to Other liabilities and to Other income for the outstanding contracts, based on similar contract values (level 2 inputs). Realized losses of $102 and $161 were recorded in Other income during the three and six months ended March 31, 2021, respectively, for all settled contracts. All contracts expire in 29 to 450 days.

REVENUE

REVENUE	6 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE The Company recognizes revenue when performance obligations identified under the terms of contracts with its customers are satisfied. A performance obligation is a promise in a contract to transfer a distinct good or service, or a bundle of goods or services, to the customer, and is the unit of accounting. A contract with a customer is an agreement which both parties have approved, that creates enforceable rights and obligations, has commercial substance and with respect to which payment terms are identified and collectability is probable. Once the Company has entered into a contract or purchase order, it is evaluated to identify performance obligations. For each performance obligation, revenue is recognized when control of the promised products is transferred to the customer, or services are satisfied under the contract or purchase order, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those products or services (the transaction price). Approximately 86% of the Company’s performance obligations are recognized at a point in time related to the manufacture and sale of a broad range of products and components primarily within the CPP and HBP Segments, and revenue is recognized when title, and risk and rewards of ownership, have transferred to the customer, which is generally upon shipment. Approximately 14% of the Company’s performance obligations are recognized over time and relate to prime or subcontractors from contract awards with the U.S. Government, as well as foreign governments and other commercial customers within our DE Segment. Revenue recognized over time are generally accounted for using an input measure to determine progress completed at the end of the period. We believe that cumulative costs incurred to date as a percentage of estimated total contract costs at completion (cost-to-cost method) is an appropriate measure of progress towards satisfaction of performance obligations recognized over time, as it most accurately depicts the progress of our work and transfer of control to our customers. Accounting for the sales and profits on performance obligations for which progress is measured using the cost-to-cost method relies on the substantial use of estimates; these projections may be revised throughout the life of a contract. Adjustments to estimates for a contract's estimated costs at completion and estimated profit or loss are often required as experience is gained, more information is obtained (even though the scope of work required under the contract may or may not change) and contract modifications occur. The impact of such adjustments to estimates is made on a cumulative basis in the period when such information has become known. For the three and six months ended March 31, 2021, income from operations included net unfavorable catch up adjustments approximating $1,423 and $3,220, respectively. For the three and six months ended March 31, 2020, income from operations included net unfavorable catch up adjustments of $2,188 and $422, respectively. Gross profit is impacted by a variety of factors, including the mix of products, systems and services, production efficiencies, price competition and general economic conditions. For contracts in which anticipated total costs exceed the total expected revenue, an estimated loss is recognized in the period when identifiable. A provision for the entire amount of the estimated loss is recorded on a cumulative basis, and is recorded as a reduction to gross margin on the Consolidated Statements of Operations and Comprehensive Income (Loss). These provisions had an immaterial impact on Griffon's Consolidated Financial Statements. The estimated remaining costs to complete loss contracts as of March 31, 2021 and September 30, 2020 were approximately $8,500 and $10,800, respectively. For a complete explanation of Griffon’s revenue accounting policies, this note should be read in conjunction with Griffon’s Annual Report on Form 10-K for the year ended September 30, 2020. See Note 13 - Business Segments for revenue from contracts with customers disaggregated by end markets, segments and geographic location. Transaction Price Allocated to the Remaining Performance Obligations On March 31, 2021, we had $353,870 of remaining performance obligations, which we also refer to as total backlog. We expect to recognize approximately 65% of our remaining performance obligations as revenue within one year, with the balance to be completed thereafter. Backlog represents the dollar value of funded orders for which work has not been performed. Backlog generally increases with bookings, and converts into revenue as we incur costs related to contractual commitments or the shipment of product. Given the nature of our business and a larger dependency on international customers, our bookings, and therefore our backlog, is impacted by the longer maturation cycles resulting in delays in the timing and amounts of such awards, which are subject to numerous factors, including fiscal constraints placed on customer budgets; political uncertainty; the timing of customer negotiations; and the timing of governmental approvals. Contract Balances Contract assets were $75,000 as of March 31, 2021 compared to $84,426 as of September 30, 2020. The $9,426 net decrease in our contract assets balance was primarily due to the timing of billings and work performed in Surveillance programs and decrease associated with the sale of Systems Engineering Group, Inc. ("SEG"). Contract assets primarily relate to the Company's right to consideration for work completed but not billed at the reporting date and are recorded in Contract costs and recognized income not yet billed, net of progress payments in the Consolidated Balance Sheets. Contract assets are transferred to receivables when the right to consideration becomes unconditional. Contract costs and recognized income not yet billed

ACQUISITIONS AND DISPOSITIONS

ACQUISITIONS AND DISPOSITIONS	6 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
ACQUISITIONS AND DISPOSITIONS	ACQUISITIONS AND DISPOSITIONS Acquisitions Griffon accounts for acquisitions under the acquisition method, in which assets acquired and liabilities assumed are recorded at fair value as of the date of acquisition using a method substantially similar to the goodwill impairment test methodology (level 3 inputs). The operating results of the acquired companies are included in Griffon’s consolidated financial statements from the date of acquisition; in each instance, Griffon is in the process of finalizing the initial purchase price allocation unless otherwise noted. On December 22, 2020, AMES acquired Quatro Design Pty Ltd (“Quatro”), a leading Australian manufacturer and supplier of glass fiber reinforced concrete landscaping products for residential, commercial, and public sector projects for a purchase price of AUD $3,500 (approximately $2,700) in cash. The purchase price is subject to additional contingent consideration of approximately AUD $1,000 (approximately $760) based on Quatro exceeding certain EBITDA performance targets in the first year. The preliminary acquired intangibles and goodwill allocated to this acquisition was AUD $2,755 (approximately $2,082) and AUD $1,648 (approximately $1,246), respectively, which was assigned to the CPP segment, and is not deductible for income tax purposes. On November 29, 2019, AMES acquired 100% of the outstanding stock of Vatre Group Limited ("Apta"), a leading United Kingdom supplier of innovative garden pottery and associated products sold to leading UK and Ireland garden centers for approximately $10,500 (GBP 8,750), inclusive of a post-closing working capital adjustment, net of cash acquired. This acquisition broadens AMES' product offerings in the UK market and increases its in-country operational footprint. The excess of the purchase price over the fair value of the net tangible and intangible assets was recorded as goodwill and is deductible for tax purposes. The purchase price allocation was finalized and allocated to goodwill of GBP 3,449, acquired intangible assets of GBP 3,454, inventory of GBP 2,914, accounts receivable and other assets of GBP 2,492 and accounts payable and other accrued liabilities of GBP 3,765, which was assigned to the CPP segment. During the three and six months ended March 31, 2021, acquisition costs were de minimis. During both the three and six months ended March 31, 2020, the Company incurred acquisition costs of $2,960. Dispositions On December 18, 2020, Defense Electronics completed the sale of its SEG business for $15,000. SEG provides sophisticated, highly technical engineering and analytical support to the Missile Defense Agency and various U.S. military commands. SEG had sales of approximately $7,000 for the first fiscal quarter ended December 31, 2020 and $31,000 for the fiscal year ended September 30, 2020. DE recorded a pre-tax gain of $5,291 ($5,251, net of tax, or $0.10 per share) related to the divestiture of SEG. The sale does not represent a strategic shift that will have a major effect on operations and financial results.

INVENTORIES

INVENTORIES	6 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Inventories are stated at the lower of cost (first-in, first-out or average cost) or market. The following table details the components of inventory: At March 31, 2021 At September 30, 2020 Raw materials and supplies $ 155,720 $ 146,351 Work in process 86,299 83,697 Finished goods 242,734 183,777 Total $ 484,753 $ 413,825

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	6 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT The following table details the components of property, plant and equipment, net: At March 31, 2021 At September 30, 2020 Land, building and building improvements $ 169,081 $ 167,005 Machinery and equipment 611,187 595,126 Leasehold improvements 53,952 53,386 834,220 815,517 Accumulated depreciation and amortization (493,215) (471,553) Total $ 341,005 $ 343,964 Depreciation and amortization expense for property, plant and equipment was $13,450 and $13,316 for the quarters ended March 31, 2021 and 2020, respectively, and $26,338 and $26,748 for the six months ended March 31, 2021 and 2020, respectively. Depreciation included in Selling, general and administrative ("SG&A") expenses was $5,014 and $4,910 for the quarters ended March 31, 2021 and 2020, respectively, and $9,720 and $9,861 for the six months ended March 31, 2021 and 2020, respectively. Remaining components of depreciation, attributable to manufacturing operations, are included in Cost of goods and services.

CREDIT LOSSES

CREDIT LOSSES	6 Months Ended
	Mar. 31, 2021
Credit Loss [Abstract]
CREDIT LOSSES	CREDIT LOSSES Effective October 1, 2020, the Company adopted accounting guidance related to accounting for credit losses on financial instruments, including trade receivables (ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments). The guidance requires companies to consider forward-looking information to estimate expected credit losses, resulting in earlier recognition of losses for receivables that are current or not yet due, which were not considered under the previous accounting guidance. The Company is exposed to credit losses primarily through sales of products and services. Trade receivables are recorded at their stated amount, less allowances for discounts, doubtful accounts and returns. The Company’s expected loss allowance methodology for trade receivables is primarily based on the aging method of the accounts receivables balances and the financial condition of its customers. The allowances represent estimated uncollectible receivables associated with potential customer defaults on contractual obligations (usually due to customers’ potential insolvency), discounts related to early payment of accounts receivables by customers and estimates for returns. The allowance for doubtful accounts includes amounts for certain customers in which a risk of default has been specifically identified, as well as an amount for customer defaults, based on a formula, when it is determined the risk of some default is probable and estimable, but cannot yet be associated with specific customers. Allowance for discounts and returns are recorded as a reduction of revenue and the provision related to the allowance for doubtful accounts is recorded in SG&A expenses. The Company also considers current and expected future economic and market conditions, such as the COVID-19 pandemic, when determining any estimate of credit losses. Generally, estimates used to determine the allowance are based on assessment of anticipated payment and all other historical, current and future information that is reasonably available. All accounts receivable amounts are expected to be collected in less than one year. Based on a review of the Company's policies and procedures across all segments, including the aging of its trade receivables, recent write-off history and other factors related to future macroeconomic conditions, Griffon determined that its method to determine credit losses and the amount of its allowances for bad debts is in accordance with this guidance in all material respects. The following table provides a roll-forward of the allowance for credit losses that is deducted from the amortized cost basis of accounts receivable to present the net amount expected to be collected: Beginning Balance, October 1, 2020 $ 8,505 Provision for expected credit losses 1,228 Amounts written off charged against the allowance (161) Other, primarily foreign currency translation 22 Ending Balance, March 31, 2021 $ 9,594

GOODWILL AND OTHER INTANGIBLES

GOODWILL AND OTHER INTANGIBLES	6 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLES	GOODWILL AND OTHER INTANGIBLES The following table provides changes in the carrying value of goodwill by segment during the six months ended March 31, 2021: At September 30, 2020 Business Acquisitions (a) Business Divestitures (b) Foreign At March 31, 2021 Consumer and Professional Products $ 232,845 $ 1,246 $ — $ 3,287 $ 237,378 Home and Building Products 191,253 — — — 191,253 Defense Electronics 18,545 — (811) — 17,734 Total $ 442,643 $ 1,246 $ (811) $ 3,287 $ 446,365 (a) The increase in the CPP segment was due to the acquisition of Quatro. (b) The decrease in the DE segment was due to the divestiture of SEG. The following table provides the gross carrying value and accumulated amortization for each major class of intangible assets: At March 31, 2021 At September 30, 2020 Gross Carrying Amount Accumulated Average Gross Carrying Amount Accumulated Customer relationships & other $ 189,189 $ 71,840 23 $ 185,940 $ 66,656 Technology and patents 19,529 8,030 13 19,464 8,360 Total amortizable intangible assets 208,718 79,870 205,404 75,016 Trademarks 228,658 — 224,640 — Total intangible assets $ 437,376 $ 79,870 $ 430,044 $ 75,016 The gross carrying amount of intangible assets was impacted by approximately $5,250 related to foreign currency translation. Amortization expense for intangible assets was $2,433 and $2,403 for the quarters ended March 31, 2021 and 2020, respectively, and $4,811 and $4,796 for the six months ended March 31, 2021 and 2020. Amortization expense for the remainder of 2021 and the next five fiscal years and thereafter, based on current intangible balances and classifications, is estimated as follows: 2021 - $4,574; 2022 - $9,376; 2023 - $9,224; 2024 - $9,198; 2025 - $9,198; 2026 - $9,198; thereafter $78,080.

INCOME TAXES

INCOME TAXES	6 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXESDuring the quarter ended March 31, 2021, the Company recognized a tax provision of $10,748 on income before taxes of $27,860, compared to a tax provision of $2,034 on income before taxes of $2,929 in the comparable prior year quarter. The current year quarter results included restructuring charges of $7,562 ($5,651, net of tax), reduction to gain on sale of the SEG business of $949 ($766, net of tax) and discrete and certain other tax provisions, net, that affect comparability of $1,913. The prior year quarter results included restructuring charges of $3,104 ($3,005, net of tax), acquisition costs of $2,960 ($2,321, net of tax), loss from debt extinguishment of $6,690 ($5,245, net of tax) and discrete tax and certain other tax benefits, net, that affect comparability of $1,413. Excluding these items, the effective tax rates for the quarters ended March 31, 2021 and 2020 were 30.0% and 35.9%, respectively.During the six months ended March 31, 2021, the Company recognized a tax provision of $20,417 on Income before taxes of $67,029, compared to a tax provision of $8,373 on income before taxes of $19,880 in the comparable prior year period. The six month period ended March 31, 2021 included restructuring charges of $18,362 ($13,951, net of tax), gain on sale of the SEG business of $5,291 ($5,251, net of tax) and discrete and certain other tax benefits, net, that affect comparability of $115. The six month period ended March 31, 2020 included restructuring charges of $9,538 ($7,153, net of tax), acquisition costs of $2,960 ($2,321, net of tax), loss from debt extinguishment of $6,690 ($5,245, net of tax) and discrete tax and certain other tax benefits, net, that affect comparability of $580. Excluding these items, the effective tax rates for the six months ended March 31, 2021 and 2020 were 31.1% and 34.4%, respectively.

LONG-TERM DEBT

LONG-TERM DEBT	6 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT At March 31, 2021 At September 30, 2020 Outstanding Balance Original Issuer Premium Capitalized Fees & Expenses Balance Sheet Coupon Interest Rate Outstanding Balance Original Issuer Premium Capitalized Fees & Expenses Balance Sheet Coupon Interest Rate Senior notes due 2028 (a) $ 1,000,000 $ 339 (14,329) $ 986,010 5.75 % $ 1,000,000 $ 363 $ (15,376) $ 984,987 5.75 % Revolver due 2025 (b) 20,622 — (1,963) 18,659 Variable 12,858 — (2,209) 10,649 Variable Finance lease - real estate (c) 15,924 — (17) 15,907 5.60 % 17,218 — (30) 17,188 5.60 % Non US lines of credit (d) 4,405 — (24) 4,381 Variable — — (30) (30) Variable Non US term loans (d) 29,870 — (133) 29,737 Variable 31,086 — (160) 30,926 Variable Other long term debt (e) 4,094 — (16) 4,078 Variable 3,260 — (16) 3,244 Variable Totals 1,074,915 339 (16,482) 1,058,772 1,064,422 363 (17,821) 1,046,964 less: Current portion (14,913) — — (14,913) (9,922) — — (9,922) Long-term debt $ 1,060,002 $ 339 $ (16,482) $ 1,043,859 $ 1,054,500 $ 363 $ (17,821) $ 1,037,042 Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 Effective Interest Rate Cash Interest Amort. Debt Amort. Debt Issuance Costs Total Interest Expense Effective Interest Rate Cash Interest Amort. Debt Amort. Total Interest Expense Senior notes due 2028 (a) 6.0 % $ 14,375 $ 12 $ 505 $ 14,892 6.0 % $ 5,566 $ — $ 135 $ 5,701 Senior notes due 2022 (a) — — — — — 5.7 % 8,040 45 628 8,713 Revolver due 2025 (b) Variable 287 — 122 409 Variable 1,819 — 165 1,984 Finance lease - real estate (c) 5.9 % 224 — 7 231 6.1 % 52 — 7 59 Non US lines of credit (d) Variable 4 — 4 8 Variable 3 — 8 11 Non US term loans (d) Variable 163 — 18 181 Variable 292 — 7 299 Other long term debt (e) Variable 115 — 1 116 Variable 132 — — 132 Capitalized interest (6) — — (6) (28) — — (28) Totals $ 15,162 $ 12 $ 657 $ 15,831 $ 15,876 $ 45 $ 950 $ 16,871 Six Months Ended March 31, 2021 Six Months Ended March 31, 2020 Effective Interest Rate Cash Interest Amort. Debt Amort. Debt Issuance Costs & Other Fees Total Interest Expense Effective Interest Rate Cash Interest Amort. Debt Premium Amort. Debt Issuance Costs & Other Fees Total Interest Expense Senior notes due 2028 (a) 6.0 % $ 28,750 $ 24 $ 1,023 $ 29,797 6.0 % $ 5,566 $ — $ 135 $ 5,701 Senior notes due 2022 (a) — — — — — 5.7 % 21,165 112 1,579 22,856 Revolver due 2025 (b) Variable 416 — 245 661 Variable 3,201 — 397 3,598 Finance lease - real estate (c) 5.6 % 456 — 13 469 6.0 % 113 — 13 126 Non US lines of credit (d) Variable 7 — 8 15 Variable 7 — 12 19 Non US term loans (d) Variable 334 — 35 369 Variable 564 — 19 583 Other long term debt (e) Variable 222 — 1 223 Variable 292 — — 292 Capitalized interest (13) — — (13) (93) — — (93) Totals $ 30,172 $ 24 $ 1,325 $ 31,521 $ 30,815 $ 112 $ 2,155 $ 33,082 (a) On June 22, 2020, in an unregistered offering through a private placement, Griffon completed the add-on offering of $150,000 principal amount of its 5.75% Senior Notes, at 100.25% of par, to Griffon's previously issued $850,000 principal amount of its 5.75% Senior Notes, at par, completed on February 19, 2020 (collectively, the “Senior Notes”). Proceeds from the Senior Notes were used to redeem the $1,000,000 of 5.25% 2022 senior notes. As of March 31, 2021, outstanding Senior Notes due totaled $1,000,000; interest is payable semi-annually on March 1 and September 1. The Senior Notes are senior unsecured obligations of Griffon guaranteed by certain domestic subsidiaries, and subject to certain covenants, limitations and restrictions. On April 22, 2020 and August 3, 2020, Griffon exchanged substantially all of the Senior Notes for substantially identical Senior Notes registered under the Securities Act of 1933, as amended (the "Securities Act"), via an exchange offer. The fair value of the Senior Notes approximated $1,060,000 on March 31, 2021 based upon quoted market prices (level 1 inputs). In connection with these transactions, Griffon capitalized $16,448 of underwriting fees and other expenses incurred related to the issuance and exchange of the 2028 Senior Notes, which is being amortized over the term of the 2028 Senior Notes. Furthermore, all of the obligations associated with the 2022 Senior Notes were discharged. Additionally, Griffon recognized a $7,925 loss on the early extinguishment of debt of the $1,000,000 principal amount of 2022 Senior Notes, comprised primarily of the write-off of $6,725 of remaining deferred financing fees, $607 of tender offer net premium expense and $593 of redemption interest expense. (b) On January 30, 2020, Griffon amended its revolving credit facility (as amended, the "Credit Agreement") to increase the maximum borrowing availability from $350,000 to $400,000, and extend its maturity date from March 22, 2021 to March 22, 2025 and modify certain other provisions of the facility. The facility includes a letter of credit sub-facility with a limit of $100,000; a multi-currency sub-facility of $200,000; and contains a customary accordion feature that permits us to request, subject to each lender's consent, an increase in the maximum aggregate amount that can be borrowed by up to an additional $100,000. Borrowings under the Credit Agreement may be repaid and re-borrowed at any time. Interest is payable on borrowings at either a LIBOR or base rate benchmark rate, plus an applicable margin, which adjusts based on financial performance. Current margins are 0.50% for base rate loans and 1.50% 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 Griffon’s material, first-tier foreign subsidiaries. At March 31, 2021, there were $20,622 of outstanding borrowings under the Credit Agreement; outstanding standby letters of credit were $16,310; and $363,068 was available, subject to certain loan covenants, for borrowing at that date. (c) Two Griffon subsidiaries have finance leases outstanding for real estate located in Troy, Ohio and Ocala, Florida. The leases mature in 2021 and 2025, respectively, and bear interest at fixed rates of approximately 5.0% and 5.6%, respectively. The Troy, Ohio lease is secured by a mortgage on the real estate and is guaranteed by Griffon. The Ocala, Florida lease contains two five (d) In November 2012, Garant G.P. (“Garant”), a Griffon wholly owned subsidiary, entered into a CAD 15,000 ($11,894 as of March 31, 2021) revolving credit facility. The facility accrues interest at LIBOR (USD) or the Bankers Acceptance Rate (CDN) plus 1.3% per annum (1.41% LIBOR USD and 1.47% Bankers Acceptance Rate CDN as of March 31, 2021). The revolving facility matures in October 2022. Garant is required to maintain a certain minimum equity. At March 31, 2021, there were no borrowings under the revolving credit facility with CAD 15,000 ($11,894 as of March 31, 2021) available for borrowing. In July 2016, Griffon Australia Holdings Pty Ltd and its Australian subsidiaries (collectively, "Griffon Australia") entered into an AUD 29,625 term loan, AUD 20,000 revolver and AUD 10,000 receivable purchase facility agreement. The term loan requires quarterly principal payments of AUD 1,250 plus interest with a balloon payment of AUD 9,625 due upon maturity in March 2022, and accrues interest at Bank Bill Swap Bid Rate “BBSY” plus 1.95% per annum (2.01% at March 31, 2021). During fiscal 2020, the term loan balance was reduced by AUD 5,000, from AUD 23,375 to AUD 18,375 with proceeds from an AUD 5,000 increase in the commitment of the receivables purchase line from AUD 10,000 to AUD 15,000. As of March 31, 2021, the term loan had an outstanding balance of AUD 13,375 ($10,192 as of March 31, 2021). The revolving facility and receivable purchase facility mature in March 2022, but are renewable upon mutual agreement with the lender. The revolving facility and receivable purchase facility accrue interest at BBSY plus 1.9% and 1.35%, respectively, per annum (1.98% and 1.41%, respectively, at March 31, 2021). At March 31, 2021, there were no balances outstanding under the revolver and the receivable purchase facility. The revolver, receivable purchase facility and the term loan are all secured by substantially all of the assets of Griffon Australia and its subsidiaries. Griffon Australia is required to maintain a certain minimum equity level and is subject to a maximum leverage ratio and a minimum fixed charges cover ratio. In July 2018, The AMES Companies UK Ltd and its subsidiaries (collectively, "AMES UK") entered into a GBP 14,000 term loan, GBP 4,000 mortgage loan and GBP 5,000 revolver. The term loan and mortgage loan require quarterly principal payments of GBP 438 and GBP 105 plus interest, respectively, and have balloon payments due upon maturity, July 2023, of GBP 7,088 and GBP 2,349, respectively. The Term Loan and Mortgage Loans each accrue interest at the GBP LIBOR Rate plus 1.8% ( 1.85% at March 31, 2021). The revolving facility matures in May 2021, but is renewable upon mutual agreement with the lender, and accrues interest at the Bank of England Base Rate plus 1.5% (1.60% as of March 31, 2021). As of March 31, 2021, the revolver had an outstanding balance of GBP $3,204 ($4,405 as of March 31, 2021) while the term and mortgage loan balances amounted to GBP 14,313 ($19,678 as of March 31, 2021). The revolver and the term loan are both secured by substantially all of the assets of AMES UK and its subsidiaries. AMES UK is subject to a maximum leverage ratio and a minimum fixed charges cover ratio. An invoice discounting arrangement was canceled and replaced by the above loan facilities. (e) Other long-term debt primarily consists of a loan with the Pennsylvania Industrial Development Authority, with the balance consisting of finance leases. On March 13, 2019, Griffon's Employee Stock Ownership Plan entered into an agreement that refinanced a term loan with a bank with an internal loan from Griffon. The internal loan interest rate is fixed at 2.91%, matures in June 2033 and requires quarterly payments of principal, currently $635, and interest. The internal loan is secured by shares purchased with the proceeds of the loan. The amount outstanding on the internal loan at March 31, 2021 was $28,608. At March 31, 2021, Griffon and its subsidiaries were in compliance with the terms and covenants of all credit and loan agreements.

SHAREHOLDERS' EQUITY

SHAREHOLDERS' EQUITY	6 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	SHAREHOLDERS’ EQUITY During 2021, the Company paid a quarterly cash dividend of $0.08 per share in each quarter, totaling $0.16 per share for the six months ended March 31, 2021. During 2020, the Company paid a quarterly cash dividend of $0.075 per share, totaling $0.30 per share for the year. A dividend payable was established for the holders of restricted shares; such dividends will be released upon vesting of the underlying restricted shares. On April 29, 2021, the Board of Directors declared a quarterly cash dividend of $0.08 per share, payable on June 17, 2021 to shareholders of record as of the close of business on May 20, 2021. Compensation expense for restricted stock and restricted stock units 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 expense for restricted stock granted to two senior executives is calculated as the maximum number of shares granted, upon achieving certain performance criteria, multiplied by the stock price as valued by a Monte Carlo Simulation Model. Compensation cost related to stock-based awards with graded vesting, generally over a period of three 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; and on January 30, 2020, shareholders approved Amendment No. 2 to the Incentive Plan, pursuant to which 1,700,000 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 5,050,000 (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 March 31, 2021, there were 437,276 shares available for grant. During the first quarter of 2021, Griffon granted 511,624 shares of restricted stock and restricted stock units. This included 226,811 restricted stock and restricted stock units, subject to certain performance conditions, with vesting periods of three years, with a total fair value of $5,500, or a weighted average fair value of $24.25 per share. Furthermore, this included 284,813 restricted stock awards granted to five executives, with vesting periods of three years and a total fair value of $5,913 or a weighted average fair value of $20.76 per share. During the second quarter of 2021, Griffon granted 731,282 shares of restricted stock to six executives. This included 203,282 shares of restricted stock to four executives, subject to certain performance conditions, with vesting periods ranging from 34 months to 60 months, with a total fair value of $4,923, or a weighted average fair value of $24.22 per share. This also included 528,000 shares of restricted stock granted to two senior executives with a vesting period of four two The following table summarizes the Company’s compensation expense relating to all stock-based incentive plans: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Restricted stock $ 4,349 $ 3,662 $ 7,777 $ 6,812 ESOP 944 658 1,724 1,490 Total stock based compensation $ 5,293 $ 4,320 $ 9,501 $ 8,302 On each of August 3, 2016 and August 1, 2018, 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 six months ended March 31, 2021, Griffon did not purchase any shares of common stock under these repurchase programs. As of March 31, 2021, an aggregate of $57,955 remains under Griffon's Board authorized repurchase programs. During the second quarter ended March 31, 2021, no shares were withheld to settle employee taxes due upon the vesting of restricted stock. During the six months ended March 31, 2021, 133,027 shares, with a market value of $2,774, or $20.85 per share, respectively, were withheld to settle employee taxes due upon the vesting of restricted stock, and were added to treasury stock. Furthermore, during the six months ended March 31, 2021, an additional 6,507 shares, with a market value of $135, or

EARNINGS PER SHARE (EPS)

EARNINGS PER SHARE (EPS)	6 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
EARNINGS PER SHARE (EPS)	EARNINGS PER SHARE (EPS) Basic EPS was calculated by dividing income available to common shareholders by the weighted average number of shares of common stock outstanding during the period. Diluted EPS was calculated by dividing income available to common shareholders by the weighted average number of shares of common stock outstanding plus additional common shares that could be issued in connection with stock based compensation. The following table is a reconciliation of the share amounts (in thousands) used in computing earnings per share: Three Months Ended March 31, Six Months Ended March 31, 2021 2020 2021 2020 Common shares outstanding 56,684 47,431 56,684 47,431 Unallocated ESOP shares (1,961) (2,159) (1,961) (2,159) Non-vested restricted stock (3,822) (3,562) (3,822) (3,562) Impact of weighted average shares (63) (145) (184) (341) Weighted average shares outstanding - basic 50,838 41,565 50,717 41,369 Incremental shares from stock based compensation 2,426 2,169 2,494 2,457 Weighted average shares outstanding - diluted 53,264 43,734 53,211 43,826

BUSINESS SEGMENTS

BUSINESS SEGMENTS	6 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
BUSINESS SEGMENTS	BUSINESS SEGMENTS Griffon reports its operations through three reportable segments, as follows: • CPP conducts its operations through AMES. Founded in 1774, AMES is the leading North American manufacturer and a global provider of branded consumer and professional tools and products for home storage and organization, landscaping, and enhancing outdoor lifestyles. CPP sells products globally through a portfolio of leading brands including True Temper, AMES, and ClosetMaid. • HBP conducts its operations through Clopay. Founded in 1964, Clopay is the largest manufacturer and marketer of garage doors and rolling steel doors in North America. Residential and commercial sectional garage doors are sold through professional dealers and leading home center retail chains throughout North America under the brands Clopay, Ideal, and Holmes. Rolling steel door and grille products designed for commercial, industrial, institutional, and retail use are sold under the CornellCookson brand. • DE conducts its operations through Telephonics, founded in 1933, a globally recognized leading provider of highly sophisticated intelligence, surveillance and communications solutions for defense, aerospace and commercial customers. Information on Griffon’s reportable segments is as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, REVENUE 2021 2020 2021 2020 Consumer and Professional Products $ 331,871 $ 274,912 $ 622,913 $ 515,988 Home and Building Products 242,811 209,829 493,292 451,210 Defense Electronics 60,150 81,609 127,918 147,590 Total consolidated net sales $ 634,832 $ 566,350 $ 1,244,123 $ 1,114,788 Disaggregation of Revenue Revenue from contracts with customers is disaggregated by end markets, segments and geographic location, as it more accurately depicts the nature and amount of the Company’s revenue. The following table presents revenue disaggregated by end market and segment: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Residential repair and remodel $ 50,560 $ 40,505 $ 96,160 $ 75,595 Retail 153,746 144,904 292,994 264,524 Residential new construction 14,540 14,884 28,055 29,857 Industrial 9,958 10,535 19,489 21,158 International excluding North America 103,067 64,084 186,215 124,854 Total Consumer and Professional Products 331,871 274,912 622,913 515,988 Residential repair and remodel 120,827 100,808 246,942 222,805 Commercial construction 94,751 86,300 190,690 178,187 Residential new construction 27,233 22,721 55,660 50,218 Total Home and Building Products 242,811 209,829 493,292 451,210 U.S. Government 35,045 53,623 82,369 96,324 International 21,497 25,021 38,392 43,554 Commercial 3,608 2,965 7,157 7,712 Total Defense Electronics 60,150 81,609 127,918 147,590 Total Consolidated Revenue $ 634,832 $ 566,350 $ 1,244,123 $ 1,114,788 The following table presents revenue disaggregated by geography based on the location of the Company's customer: For the Three Months Ended March 31, 2021 2020 CPP HBP DE Total CPP HBP DE Total United States $ 205,368 $ 230,955 $ 34,166 $ 470,489 $ 191,412 $ 199,060 $ 55,071 $ 445,543 Europe 38,965 41 5,791 44,797 24,737 5 9,880 34,622 Canada 21,778 9,797 1,925 33,500 17,515 7,867 4,209 29,591 Australia 63,691 — 122 63,813 39,032 — 189 39,221 All other countries 2,069 2,018 18,146 22,233 2,216 2,897 12,260 17,373 Consolidated revenue $ 331,871 $ 242,811 $ 60,150 $ 634,832 $ 274,912 $ 209,829 $ 81,609 $ 566,350 For the Six Months Ended March 31, 2021 2020 CPP HBP DE Total CPP HBP DE Total United States $ 388,810 $ 467,486 $ 81,544 $ 937,840 $ 351,570 $ 426,010 $ 101,214 $ 878,794 Europe 52,121 41 12,696 64,858 31,342 28 15,865 47,235 Canada 43,893 21,285 3,754 68,932 35,296 19,120 6,783 61,199 Australia 133,231 — 441 133,672 93,260 — 795 94,055 All other countries 4,858 4,480 29,483 38,821 4,520 6,052 22,933 33,505 Consolidated revenue $ 622,913 $ 493,292 $ 127,918 $ 1,244,123 $ 515,988 $ 451,210 $ 147,590 $ 1,114,788 Griffon evaluates performance and allocates resources based on each segment's operating results before interest income and expense, income taxes, depreciation and amortization, unallocated amounts (mainly corporate overhead), restructuring charges, loss from debt extinguishment and acquisition related expenses, as well as other items that may affect comparability, as applicable (“Segment adjusted EBITDA”). Griffon believes this information is useful to investors for the same reason. The following table provides a reconciliation of Segment adjusted EBITDA to Income before taxes: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Segment adjusted EBITDA: Consumer and Professional Products $ 37,423 $ 25,027 $ 70,136 $ 46,953 Home and Building Products 40,060 30,635 88,429 71,336 Defense Electronics 2,220 4,248 7,805 8,723 Segment adjusted EBITDA 79,703 59,910 166,370 127,012 Unallocated amounts, excluding depreciation * (11,922) (11,947) (23,949) (23,889) Adjusted EBITDA 67,781 47,963 142,421 103,123 Net interest expense (15,527) (16,561) (31,172) (32,511) Depreciation and amortization (15,883) (15,719) (31,149) (31,544) Loss from debt extinguishment — (6,690) — (6,690) Restructuring charges (7,562) (3,104) (18,362) (9,538) Acquisition costs — (2,960) — (2,960) Gain (adjustment) on sale of SEG business (949) — 5,291 — Income before taxes $ 27,860 $ 2,929 $ 67,029 $ 19,880 * Unallocated amounts typically include general corporate expenses not attributable to a reportable segment. For the Three Months Ended March 31, For the Six Months Ended March 31, DEPRECIATION and AMORTIZATION 2021 2020 2021 2020 Segment: Consumer and Professional Products $ 8,620 $ 8,222 $ 16,819 $ 16,453 Home and Building Products 4,379 4,668 8,720 9,468 Defense Electronics 2,734 2,676 5,410 5,320 Total segment depreciation and amortization 15,733 15,566 30,949 31,241 Corporate 150 153 200 303 Total consolidated depreciation and amortization $ 15,883 $ 15,719 $ 31,149 $ 31,544 CAPITAL EXPENDITURES Segment: Consumer and Professional Products $ 6,813 $ 3,800 $ 13,720 $ 7,532 Home and Building Products 1,998 3,556 4,113 11,495 Defense Electronics 3,247 1,921 6,151 3,210 Total segment 12,058 9,277 23,984 22,237 Corporate 2 70 2 282 Total consolidated capital expenditures $ 12,060 $ 9,347 $ 23,986 $ 22,519 ASSETS At March 31, 2021 At September 30, 2020 Segment assets: Consumer and Professional Products $ 1,408,545 $ 1,255,127 Home and Building Products 604,325 606,785 Defense Electronics 288,019 329,128 Total segment assets 2,300,889 2,191,040 Corporate 216,571 248,902 Total continuing assets 2,517,460 2,439,942 Assets of discontinued operations 6,820 8,497 Consolidated total $ 2,524,280 $ 2,448,439

EMPLOYEE BENEFIT PLANS

EMPLOYEE BENEFIT PLANS	6 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
EMPLOYEE BENEFIT PLANS	EMPLOYEE BENEFIT PLANS Defined benefit pension expense (income) included in Other Income (Expense), net was as follows: Three Months Ended March 31, Six Months Ended March 31, 2021 2020 2021 2020 Interest cost $ 745 $ 1,151 $ 1,489 $ 2,302 Expected return on plan assets (2,545) (2,586) (5,089) (5,172) Amortization: Prior service cost — 4 — 8 Recognized actuarial loss 1,573 1,042 3,146 2,084 Net periodic expense (income) $ (227) $ (389) $ (454) $ (778)

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	6 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS Issued but not yet effective accounting pronouncements In August 2018, the Financial Accounting Standards Board ("FASB") issued guidance to clarify disclosure requirements related to defined benefit pension and other post-retirement plans. The guidance is effective for fiscal years beginning after December 15, 2020, with early adoption permitted, and is effective for the Company in our fiscal year beginning in October 1, 2021. We are currently evaluating the effects that the adoption of this guidance will have on our the related pension disclosures. In December 2019, the FASB issued guidance on simplifying the accounting for income taxes by clarifying and amending existing guidance related to the recognition of franchise tax, the evaluation of a step up in the tax basis of goodwill, and the effects of enacted changes in tax laws or rates in the effective tax rate computation, among other clarifications. Our effective date for adoption of this Accounting Standards Update ("ASU") is our fiscal year beginning October 1, 2021 with early adoption permitted. We are currently evaluating the effects that the adoption of this guidance will have on our consolidated financial statements and the related disclosures. New Accounting Standards Implemented In April 2019, the FASB issued guidance relating to accounting for credit losses on financial instruments, including trade receivables, and derivatives and hedging. This guidance is effective for the Company beginning in fiscal 2021. Adoption of this standard did not have a material impact on our consolidated financial statements and the related disclosures. In August 2018, the FASB issued guidance which modifies the disclosures on fair value measurements by removing the requirement to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy and the policy for timing of such transfers. This guidance expands the disclosure requirements for Level 3 fair value measurements, primarily focused on changes in unrealized gains and losses included in other comprehensive income (loss). This guidance is effective for the Company beginning in fiscal 2021. Adoption of this standard did not have a material impact on our consolidated financial statements and the related disclosures. In March 2020, the SEC adopted amendments to the financial disclosure requirements for guarantors and issuers of guaranteed securities registered or being registered in Rule 3-10 of Regulation S-X, and affiliates whose securities collateralize securities registered or being registered in Rule 3-16 of Regulation S-X (SEC Release No. 33-10762). The amendment replaces the requirement to present condensed consolidating financial statements, comprised of balance sheets and statements of operations, comprehensive income and cash flows for all periods presented, with summarized financial information of the guarantor only for the most recently completed fiscal year and any subsequent interim period. We adopted the amendments to the disclosure requirements during the first quarter of fiscal 2021. This amendment did not have an impact on our consolidated financial statements as this amendment simplifies the financial disclosures required in our guarantor and non-guarantor financial information. See Part I, Item 2, Management’s Discussion and Analysis of Financial Condition and Results of Operations—Supplemental Guarantor Financial Information. The Company has implemented all new accounting pronouncements that are in effect and that may impact its financial statements, and does not believe that there are any other new accounting pronouncements that have been issued that might have a material impact on its financial position or results of operations.

DISCONTINUED OPERATIONS

DISCONTINUED OPERATIONS	6 Months Ended
	Mar. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
DISCONTINUED OPERATIONS	DISCONTINUED OPERATIONS The following amounts summarize the total assets and liabilities related to the Installation Services and other discontinued activities which have been segregated from Griffon’s continuing operations, and are reported as assets and liabilities of discontinued operations in the Condensed Consolidated Balance Sheets: At March 31, 2021 At September 30, 2020 Assets of discontinued operations: Prepaid and other current assets $ 1,525 $ 2,091 Other long-term assets 5,295 6,406 Total assets of discontinued operations $ 6,820 $ 8,497 Liabilities of discontinued operations: Accrued liabilities, current $ 4,600 $ 3,797 Other long-term liabilities 6,415 7,014 Total liabilities of discontinued operations $ 11,015 $ 10,811

RESTRUCTURING CHARGES

RESTRUCTURING CHARGES	6 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
RESTRUCTURING CHARGES	RESTRUCTURING CHARGES In November 2019, Griffon announced the development of a next-generation business platform for CPP to enhance the growth, efficiency, and competitiveness of its U.S. operations, and on November 12, 2020, Griffon announced that CPP is broadening this strategic initiative to include additional North American facilities, the AMES UK and Australia businesses, and a manufacturing facility in China. The expanded focus of this initiative leverages the same three key development areas being executed within our U.S. operations. First, certain AMES global operations will be consolidated to optimize facilities footprint and talent. Second, strategic investments in automation and facilities expansion will be made to increase the efficiency of our manufacturing and fulfillment operations, and support e-commerce growth. Third, multiple independent information systems will be unified into a single data and analytics platform, which will serve the whole AMES global enterprise. Expanding the roll-out of the new business platform from our AMES U.S. operations to include AMES’ global operations will extend the duration of the project by one year, with completion now expected by the end of calendar year 2023. When fully implemented, these actions will result in annual cash savings of $30,000 to $35,000 and a reduction in inventory of $30,000 to $35,000, both based on fiscal 2020 operating levels. The cost to implement this new business platform, over the duration of the project, will include one-time charges of approximately $65,000 and capital investments of approximately $65,000. The one-time charges are comprised of $46,000 of cash charges, which includes $26,000 of personnel-related costs such as training, severance, and duplicate personnel costs as well as $20,000 of facility and lease exit costs. The remaining $19,000 of charges are non-cash and are primarily related to asset write-downs. In the quarter and six months ended March 31, 2021, CPP incurred pre-tax restructuring and related exit costs approximating $7,502 and $10,581, respectively. During the six months ended March 31, 2021, cash charges totaled $7,891 and non-cash, asset-related charges totaled $2,690; the cash charges included $1,084 for one-time termination benefits and other personnel-related costs and $6,807 for facility and lease exit costs primarily driven by the consolidation of distribution facilities. Non-cash charges of $2,690 predominantly related to inventory that have no recoverable value. During the six months ended March 31, 2021, headcount was reduced by 65. In the quarter and six months ended March 31, 2020, CPP incurred pre-tax restructuring and related exit costs approximating $3,104 and $9,538, respectively. During the six months ended March 31, 2020, cash charges totaled $4,846 and non-cash, asset-related charges totaled $4,692; the cash charges included $3,792 for one-time termination benefits and other personnel-related costs and $1,054 for facility exit costs. Non-cash charges included a $1,968 impairment charge related to a facility's operating lease as well as $671 of leasehold improvements made to the leased facility and $304 of inventory that have no recoverable value, and a $1,749 impairment charge related to machinery and equipment that have no recoverable value at one of the Company's owned manufacturing locations. In September 2020, the DE Voluntary Employee Retirement Plan was initiated, which was subsequently followed by a reduction in force in November 2020, to improve efficiencies by combining functions and responsibilities. The combined actions resulted in severance charges of approximately $4,300, with $2,120 recognized in the fourth quarter of fiscal 2020, and the remaining $2,180 was recognized during the six months ended March 31, 2021. These actions reduced headcount by approximately 90 people. In addition, charges of $5,601 were recorded during the quarter ended December 31, 2020, primarily related to exiting our older weather radar product lines. A summary of the restructuring and other related charges included in Cost of goods and services and SG&A expenses in the Company's Condensed Consolidated Statements of Operations were as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Cost of goods and services $ 3,337 $ 1,353 $ 9,762 $ 4,076 Selling, general and administrative expenses 4,225 1,751 8,600 5,462 Total restructuring charges $ 7,562 $ 3,104 $ 18,362 $ 9,538 For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Personnel related costs $ 782 $ 1,658 $ 3,264 $ 3,792 Facilities, exit costs and other 4,283 914 6,807 1,054 Non-cash facility and other 2,497 532 8,291 4,692 Total $ 7,562 $ 3,104 $ 18,362 $ 9,538 The following table summarizes the accrued liabilities of the Company's restructuring actions: Cash Charges Non-Cash Personnel related costs Facilities & Facility and Other Costs Total Accrued liability at September 30, 2020 $ 2,701 $ 264 $ — $ 2,965 Q1 Restructuring charges 2,482 2,524 5,794 10,800 Q1 Cash payments (1,598) (2,534) — (4,132) Q1 Non-cash charges — — (5,794) (5,794) Accrued liability at December 31, 2020 $ 3,585 $ 254 $ — $ 3,839 Q2 Restructuring charges 782 4,283 2,497 7,562 Q2 Cash payments (3,840) (4,273) — (8,113) Q2 Non-cash charges — — (2,497) (2,497) Accrued liability at March 31, 2021 $ 527 $ 264 $ — $ 791

OTHER INCOME (EXPENSE)

OTHER INCOME (EXPENSE)	6 Months Ended
	Mar. 31, 2021
Other Income and Expenses [Abstract]
OTHER INCOME (EXPENSE)	OTHER INCOME (EXPENSE) For the quarters ended March 31, 2021 and 2020, Other income (expense) of $847 and $615, respectively, includes $320 and $745, respectively, of net currency exchange gains in connection with the translation of receivables and payables denominated in currencies other than the functional currencies of Griffon and its subsidiaries, net periodic benefit plan income of $227 and $389, respectively, as well as $55 and $(230), respectively, of net investment income (loss).

WARRANTY LIABILITY

WARRANTY LIABILITY	6 Months Ended
	Mar. 31, 2021
Product Warranties Disclosures [Abstract]
WARRANTY LIABILITY	WARRANTY LIABILITY DE offers warranties against product defects for periods generally ranging from one one Changes in Griffon’s warranty liability, included in Accrued liabilities, were as follows: Three Months Ended March 31, Six Months Ended March 31, 2021 2020 2021 2020 Balance, beginning of period $ 10,834 $ 7,344 $ 10,843 $ 7,894 Warranties issued and changes in estimated pre-existing warranties 6,477 4,862 11,216 8,227 Actual warranty costs incurred (4,633) (4,417) (9,381) (8,332) Balance, end of period $ 12,678 $ 7,789 $ 12,678 $ 7,789

OTHER COMPREHENSIVE INCOME (LOS

OTHER COMPREHENSIVE INCOME (LOSS)	6 Months Ended
	Mar. 31, 2021
OCI, Net of Tax [Abstract]
OTHER COMPREHENSIVE INCOME (LOSS)	OTHER COMPREHENSIVE INCOME (LOSS) The amounts recognized in other comprehensive income (loss) were as follows: For the Three Months Ended March 31, 2021 2020 Pre-tax Tax Net of tax Pre-tax Tax Net of tax Foreign currency translation adjustments $ 1,739 $ — $ 1,739 $ (16,471) $ — $ (16,471) Pension and other defined benefit plans 1,585 (340) 1,245 847 (178) 669 Cash flow hedges 2,559 (768) 1,791 1,383 (415) 968 Total other comprehensive income (loss) $ 5,883 $ (1,108) $ 4,775 $ (14,241) $ (593) $ (14,834) For the Six Months Ended March 31, 2021 2020 Pre-tax Tax Net of tax Pre-tax Tax Net of tax Foreign currency translation adjustments $ 13,862 $ — $ 13,862 $ (10,001) $ — $ (10,001) Pension and other defined benefit plans 3,735 (784) 2,951 1,694 (353) 1,341 Cash flow hedges 1,576 (473) 1,103 953 (286) 667 Total other comprehensive income (loss) $ 19,173 $ (1,257) $ 17,916 $ (7,354) $ (639) $ (7,993) The components of Accumulated other comprehensive income (loss) are as follows: At March 31, 2021 At September 30, 2020 Foreign currency translation adjustments $ (11,821) $ (25,683) Pension and other defined benefit plans (43,647) (46,598) Change in Cash flow hedges 1,292 189 $ (54,176) $ (72,092) Amounts reclassified from accumulated other comprehensive income (loss) to income were as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, Gain (Loss) 2021 2020 2021 2020 Pension amortization $ (1,573) $ (1,046) $ (3,146) $ (2,092) Cash flow hedges (1,741) 1,050 (2,399) 994 Total gain (loss) $ (3,314) $ 4 (5,545) (1,098) Tax benefit (expense) 696 (1) 1,165 231 Total $ (2,618) $ 3 $ (4,380) $ (867)

LEASES

LEASES	6 Months Ended
	Mar. 31, 2021
Leases [Abstract]
LEASES	LEASES The Company recognizes right-of-use ("ROU") assets and lease liabilities on the balance sheet, with the exception of leases with a term of twelve months or less. The Company determines if an arrangement is a lease at inception. The ROU assets and short and long-term liabilities associated with our Operating leases are shown as separate line items on our Condensed Consolidated Balance Sheets. Finance leases are included in property, plant, and equipment, net, other accrued liabilities, and other non-current liabilities. The Company's finance leases are immaterial. ROU assets, along with any other related long-lived assets, are periodically evaluated for impairment. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. We use the implicit rate when readily determinable. Our determination of the lease term may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. For operating leases, fixed lease payments are recognized as operating lease cost on a straight-line basis over the lease term. For finance leases and impaired operating leases, the ROU asset is depreciated on a straight-line basis over the remaining lease term, along with recognition of interest expense associated with accretion of the lease liability. For leases with a lease term of 12 months or less (a "Short-term" lease), any fixed lease payments are recognized on a straight-line basis over such term, and are not recognized on the Condensed Consolidated Balance Sheets. Variable lease cost for both operating and finance leases, if any, is recognized as incurred. The Company has lease agreements that contain both lease and non-lease components. For real estate leases, we account for lease components together with non-lease components (e.g., common-area maintenance). Components of operating lease costs are as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Fixed $ 9,970 $ 9,187 $ 20,010 $ 18,739 Variable (a), (b) 2,087 1,823 4,134 3,576 Short-term (b) 1,053 1,393 2,167 2,823 Total $ 13,110 $ 12,403 $ 26,311 $ 25,138 (a) Primarily relates to common-area maintenance and property taxes. (b) Not recorded on the balance sheet. Supplemental cash flow information were as follows: For the Six Months Ended March 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 22,099 $ 21,582 Financing cash flows from finance leases 1,865 1,940 Total $ 23,964 $ 23,522 Supplemental Condensed Consolidated Balance Sheet information related to leases were as follows: March 31, 2021 September 30, 2020 Operating Leases: Right of use assets: Operating right-of-use assets $ 154,929 $ 161,627 Lease Liabilities: Current portion of operating lease liabilities $ 30,685 $ 31,848 Long-term operating lease liabilities 128,714 136,054 Total operating lease liabilities $ 159,399 $ 167,902 Finance Leases: Property, plant and equipment, net (1) $ 18,068 $ 18,774 Lease Liabilities: Notes payable and current portion of long-term debt $ 3,110 $ 3,352 Long-term debt, net 14,950 15,339 Total financing lease liabilities $ 18,060 $ 18,691 (1) Finance lease assets are recorded net of accumulated depreciation of $4,296 and $2,383 as of March 31, 2021 and September 30, 2020, respectively. Two Griffon subsidiaries have finance leases outstanding for real estate located in Troy, Ohio and Ocala, Florida. The leases mature in 2021 and 2025, respectively, and bear interest at fixed rates of approximately 5.0% and 5.6%, respectively. The Troy, Ohio lease is secured by a mortgage on the real estate and is guaranteed by Griffon. The Ocala, Florida lease contains two five As of March 31, 2021 and September 30, 2020, $15,907 and $17,188, respectively, was outstanding, net of issuance costs. The remaining lease liability balance relates to finance equipment leases. The aggregate future maturities of lease payments for operating leases and finance leases as of March 31, 2021 are as follows (in thousands): Operating Leases Finance Leases 2020 (a) $ 19,128 $ 2,381 2021 34,484 3,087 2022 26,884 2,749 2023 20,180 2,195 2024 18,214 2,077 2025 12,376 2,075 Thereafter 63,859 7,777 Total lease payments 195,125 22,341 Less: Imputed Interest (35,726) (4,281) Present value of lease liabilities $ 159,399 $ 18,060 (a) Excluding the six months ended March 31, 2021. Average lease terms and discount rates at March 31, 2021 were as follows: Weighted-average remaining lease term (years) Operating leases 8.1 Finance Leases 8.2 Weighted-average discount rate Operating Leases 4.45 % Finance Leases 5.50 %
LEASES	LEASES The Company recognizes right-of-use ("ROU") assets and lease liabilities on the balance sheet, with the exception of leases with a term of twelve months or less. The Company determines if an arrangement is a lease at inception. The ROU assets and short and long-term liabilities associated with our Operating leases are shown as separate line items on our Condensed Consolidated Balance Sheets. Finance leases are included in property, plant, and equipment, net, other accrued liabilities, and other non-current liabilities. The Company's finance leases are immaterial. ROU assets, along with any other related long-lived assets, are periodically evaluated for impairment. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. We use the implicit rate when readily determinable. Our determination of the lease term may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. For operating leases, fixed lease payments are recognized as operating lease cost on a straight-line basis over the lease term. For finance leases and impaired operating leases, the ROU asset is depreciated on a straight-line basis over the remaining lease term, along with recognition of interest expense associated with accretion of the lease liability. For leases with a lease term of 12 months or less (a "Short-term" lease), any fixed lease payments are recognized on a straight-line basis over such term, and are not recognized on the Condensed Consolidated Balance Sheets. Variable lease cost for both operating and finance leases, if any, is recognized as incurred. The Company has lease agreements that contain both lease and non-lease components. For real estate leases, we account for lease components together with non-lease components (e.g., common-area maintenance). Components of operating lease costs are as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Fixed $ 9,970 $ 9,187 $ 20,010 $ 18,739 Variable (a), (b) 2,087 1,823 4,134 3,576 Short-term (b) 1,053 1,393 2,167 2,823 Total $ 13,110 $ 12,403 $ 26,311 $ 25,138 (a) Primarily relates to common-area maintenance and property taxes. (b) Not recorded on the balance sheet. Supplemental cash flow information were as follows: For the Six Months Ended March 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 22,099 $ 21,582 Financing cash flows from finance leases 1,865 1,940 Total $ 23,964 $ 23,522 Supplemental Condensed Consolidated Balance Sheet information related to leases were as follows: March 31, 2021 September 30, 2020 Operating Leases: Right of use assets: Operating right-of-use assets $ 154,929 $ 161,627 Lease Liabilities: Current portion of operating lease liabilities $ 30,685 $ 31,848 Long-term operating lease liabilities 128,714 136,054 Total operating lease liabilities $ 159,399 $ 167,902 Finance Leases: Property, plant and equipment, net (1) $ 18,068 $ 18,774 Lease Liabilities: Notes payable and current portion of long-term debt $ 3,110 $ 3,352 Long-term debt, net 14,950 15,339 Total financing lease liabilities $ 18,060 $ 18,691 (1) Finance lease assets are recorded net of accumulated depreciation of $4,296 and $2,383 as of March 31, 2021 and September 30, 2020, respectively. Two Griffon subsidiaries have finance leases outstanding for real estate located in Troy, Ohio and Ocala, Florida. The leases mature in 2021 and 2025, respectively, and bear interest at fixed rates of approximately 5.0% and 5.6%, respectively. The Troy, Ohio lease is secured by a mortgage on the real estate and is guaranteed by Griffon. The Ocala, Florida lease contains two five As of March 31, 2021 and September 30, 2020, $15,907 and $17,188, respectively, was outstanding, net of issuance costs. The remaining lease liability balance relates to finance equipment leases. The aggregate future maturities of lease payments for operating leases and finance leases as of March 31, 2021 are as follows (in thousands): Operating Leases Finance Leases 2020 (a) $ 19,128 $ 2,381 2021 34,484 3,087 2022 26,884 2,749 2023 20,180 2,195 2024 18,214 2,077 2025 12,376 2,075 Thereafter 63,859 7,777 Total lease payments 195,125 22,341 Less: Imputed Interest (35,726) (4,281) Present value of lease liabilities $ 159,399 $ 18,060 (a) Excluding the six months ended March 31, 2021. Average lease terms and discount rates at March 31, 2021 were as follows: Weighted-average remaining lease term (years) Operating leases 8.1 Finance Leases 8.2 Weighted-average discount rate Operating Leases 4.45 % Finance Leases 5.50 %

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal and environmental Peekskill Site. Lightron Corporation (“Lightron”), a wholly-owned subsidiary of Griffon, once conducted operations at a location in the Town of Cortlandt, New York, just outside the city of Peekskill, New York (the “Peekskill Site”) owned by ISC Properties, Inc. (“ISCP”), a wholly-owned subsidiary of Griffon. ISCP sold the Peekskill Site in November 1982. Subsequently, ISCP was advised by the Department of Environmental Conservation of New York State (the "DEC") that sampling at the Peekskill Site and in a creek near the Peekskill Site indicated concentrations of solvents and other chemicals common to prior plating operations by a Lightron subsidiary. In 1996, ISCP entered into a consent order with the DEC (the “Consent Order”), pursuant to which ISCP was required to perform a remedial investigation and prepare a feasibility study (the “Feasibility Study”). After completing the initial remedial investigation, ISCP conducted supplemental remedial investigations over the next several years, including soil vapor investigations, as required by the Consent Order. In April 2009, the DEC advised ISCP that both the DEC and the New York State Department of Health had reviewed and accepted an August 2007 Remedial Investigation Report and an Additional Data Collection Summary Report dated January 30, 2009. ISCP submitted to the DEC a draft Feasibility Study which was accepted and approved by the DEC in February 2011. ISCP satisfied its obligations under the Consent Order when DEC approved the Remedial Investigation and Feasibility Study for the Peekskill Site. In June 2011 the DEC issued a Record of Decision that set forth a Remedial Action Plan for the Peekskill Site that identified the specific remedies selected and responded to public comments. The cost of the remedy proposed by DEC in its Remedial Action Plan was approximately $10,000. Following issuance of the Remedial Action Plan, the DEC implemented a portion of its plan, and also performed additional investigation for the presence of metals in soils and sediments downstream from the Peekskill Site. During this investigation metals were found to be present in sediments further downstream from the Peekskill site than previously detected. In August 2018, the DEC sent a letter to the United States Environmental Protection Agency (the “EPA”), in which the DEC requested that the Peekskill Site be nominated by the EPA for inclusion on the National Priorities List under CERCLA (the “NPL”). Based on the DEC’s request and an analysis by a consultant retained by the EPA, on May 15, 2019 the EPA added the Peekskill Site to the NPL and has since announced that it is performing a Remedial Investigation/Feasibility Study. On August 25, 2020, the EPA sent a letter to several parties, including Lightron and ISCP, requesting that each such party inform the EPA as to whether it would be willing to enter into discussions regarding implementation of a Remedial Investigation/Feasibility Study (“RI/FS”). The EPA also sent a request for information to each party under Section 104(e) of CERCLA. Lightron and ISCP have informed the EPA that they are willing to participate in discussions regarding implementation of the RI/FS. Lightron and ISCP have also submitted responses to certain items contained in the Section 104(e) information request, with additional responses to follow. The current owner of the property, which acquired the Peekskill Site from ISCP in 1982 and has no relationship with Lightron or ISCP, has also informed the EPA that it is willing to discuss implementation of the RI/FS, and has also received, and submitted certain information in response to, a Section 104(e) information request. The EPA may decide to implement the RI/FS, on its own or through the use of consultants, may reach agreement with one or more parties to perform the RI/FS, or may offer to negotiate with one or more parties to accept a settlement addressing the potential liability of such parties for investigation and/or remediation at the Peekskill Site. Should the EPA implement the RI/FS, or perform further studies and/or subsequently remediate the site, without first reaching agreement with one or more relevant parties, the EPA would likely seek reimbursement for the costs incurred from such parties. Lightron has not engaged in any operations in over three decades. ISCP functioned solely as a real estate holding company, and has not held any real property in over three decades. Griffon does not acknowledge any responsibility to perform any investigation or remediation at the Peekskill Site. Union Fork and Hoe, Frankfort, NY site. The former Union Fork and Hoe property in Frankfort, New York was acquired by AMES in 2006 as part of a larger acquisition, and has historic site contamination involving chlorinated solvents, petroleum hydrocarbons and metals. AMES entered into an Order on Consent with the New York State Department of Environmental Conservation (“DEC”). While the Order is without admission or finding of liability or acknowledgment that there has been a release of hazardous substances at the site, the Order required Ames to perform a remedial investigation of certain portions of the property and to recommend a remediation option. In 2011, remediation of chlorinated solvents in the groundwater was completed to the satisfaction of DEC. In 2018, Ames submitted a Feasibility Study recommending that the remaining soil contamination involving metals and petroleum be covered, excavated and removed to a licensed off-site location or placed under a cover on-site. DEC approved the selection of this remedy in 2019 by issuing a Record of Decision (“ROD”). In June 2020, Ames completed the remediation required by the ROD and filed a Construction Completion Report, a Site Management Plan and an environmental easement with DEC. While Ames was implementing the remediation required by the ROD, DEC requested additional investigation of a small area on the site and of an area adjacent to the site perimeter. Ames investigated the on-site area and has completed remediation of that small area under a workplan approved by DEC. At the request of DEC, Ames has also submitted a workplan to investigate the areas adjacent to the site perimeter. AMES has a number of defenses to liability in this matter, including its rights under a previous Consent Judgment entered into between DEC and a predecessor of AMES relating to the site. Ames’ insurer has accepted Ames’ claim for a substantial portion of the costs incurred and to be incurred for both the on-site and off-site activities. U.S. Government investigations and claims Defense contracts and subcontracts, including Griffon’s contracts and subcontracts, are subject to audit and review by various agencies and instrumentalities of the United States government, including among others, the Defense Contract Audit Agency, the Defense Criminal Investigative Service, and the Department of Justice which has responsibility for asserting claims on behalf of the U.S. Government. In general, departments and agencies of the U.S. Government have the authority to investigate various transactions and operations of Griffon, and the results of such investigations may lead to administrative, civil or criminal proceedings, the ultimate outcome of which could be fines, penalties, repayments or compensatory or treble damages. U.S. Government regulations provide that certain findings against a contractor may lead to suspension or debarment from future U.S. Government contracts or the loss of export privileges for a company or an operating division or subdivision. Suspension or debarment could have a material adverse effect on Telephonics because of its reliance on government contracts. General legal Griffon is subject to various laws and regulations relating to the protection of the environment and is a party to legal proceedings arising in the ordinary course of business. Management believes, based on facts presently known to it, that the resolution of the matters above and such other matters will not have a material adverse effect on Griffon’s consolidated financial position, results of operations or cash flows.

DESCRIPTION OF BUSINESS AND B_2

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Policies)	6 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”) for interim financial information, and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, these financial statements do not include all the information and footnotes required by US GAAP for complete financial statements. As such, they should be read together with Griffon’s Annual Report on Form 10-K for the year ended September 30, 2020, which provides a more complete explanation of Griffon’s accounting policies, financial position, operating results, business, properties and other matters. In the opinion of management, these financial statements reflect all adjustments considered necessary for a fair statement of interim results. Griffon’s CPP operations are seasonal; for this and other reasons, the financial results of the Company for any interim period are not necessarily indicative of the results for the full year. The condensed consolidated balance sheet information at September 30, 2020 was derived from the audited financial statements included in Griffon’s Annual Report on Form 10-K for the year ended September 30, 2020. The condensed consolidated financial statements include the accounts of Griffon and all subsidiaries. Intercompany accounts and transactions have been eliminated in consolidation. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting periods. These estimates may be adjusted due to changes in economic, industry or customer financial conditions, as well as changes in technology or demand. Significant estimates include allowances for doubtful accounts receivable and returns, net realizable value of inventories, restructuring reserves, valuation of goodwill and intangible assets, sales, profits and loss recognition for performance obligations satisfied over time, assumptions associated with pension benefit obligations and income or expenses, useful lives associated with depreciation and amortization of intangible and fixed assets, warranty reserves, sales incentive accruals, assumption associated with stock based compensation valuation, income taxes and tax valuation reserves, environmental reserves, legal reserves, insurance reserves, the valuation of assets and liabilities of discontinued operations, assumptions associated with valuation of acquired assets and assumed liabilities of acquired companies and the accompanying disclosures. These estimates are based on management’s best knowledge of current events and actions Griffon may undertake in the future. Actual results may ultimately differ from these estimates. Certain amounts in the prior year have been reclassified to conform to current year presentation.
Fair Value Measurements	The carrying values of cash and equivalents, accounts receivable, accounts and notes payable, and revolving credit and variable interest rate debt approximate fair value due to either the short-term nature of such instruments or the fact that the interest rate of the revolving credit and variable rate debt is based upon current market rates. Applicable accounting guidance establishes a fair value hierarchy requiring the Company to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. A financial instrument’s categorization within the hierarchy is based on the lowest level of input that is significant to the fair value measurement. The accounting guidance establishes three levels of inputs that may be used to measure fair value, as follows: • Level 1 inputs are measured and recorded at fair value based upon quoted prices in active markets for identical assets. • Level 2 inputs include inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of assets or liabilities. • Level 3 inputs are unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions.
Inventories	Inventories are stated at the lower of cost (first-in, first-out or average cost) or market.
Issued but not yet effective accounting pronouncements and New Accounting Standards Implemented	Issued but not yet effective accounting pronouncements In August 2018, the Financial Accounting Standards Board ("FASB") issued guidance to clarify disclosure requirements related to defined benefit pension and other post-retirement plans. The guidance is effective for fiscal years beginning after December 15, 2020, with early adoption permitted, and is effective for the Company in our fiscal year beginning in October 1, 2021. We are currently evaluating the effects that the adoption of this guidance will have on our the related pension disclosures. In December 2019, the FASB issued guidance on simplifying the accounting for income taxes by clarifying and amending existing guidance related to the recognition of franchise tax, the evaluation of a step up in the tax basis of goodwill, and the effects of enacted changes in tax laws or rates in the effective tax rate computation, among other clarifications. Our effective date for adoption of this Accounting Standards Update ("ASU") is our fiscal year beginning October 1, 2021 with early adoption permitted. We are currently evaluating the effects that the adoption of this guidance will have on our consolidated financial statements and the related disclosures. New Accounting Standards Implemented In April 2019, the FASB issued guidance relating to accounting for credit losses on financial instruments, including trade receivables, and derivatives and hedging. This guidance is effective for the Company beginning in fiscal 2021. Adoption of this standard did not have a material impact on our consolidated financial statements and the related disclosures. In August 2018, the FASB issued guidance which modifies the disclosures on fair value measurements by removing the requirement to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy and the policy for timing of such transfers. This guidance expands the disclosure requirements for Level 3 fair value measurements, primarily focused on changes in unrealized gains and losses included in other comprehensive income (loss). This guidance is effective for the Company beginning in fiscal 2021. Adoption of this standard did not have a material impact on our consolidated financial statements and the related disclosures. In March 2020, the SEC adopted amendments to the financial disclosure requirements for guarantors and issuers of guaranteed securities registered or being registered in Rule 3-10 of Regulation S-X, and affiliates whose securities collateralize securities registered or being registered in Rule 3-16 of Regulation S-X (SEC Release No. 33-10762). The amendment replaces the requirement to present condensed consolidating financial statements, comprised of balance sheets and statements of operations, comprehensive income and cash flows for all periods presented, with summarized financial information of the guarantor only for the most recently completed fiscal year and any subsequent interim period. We adopted the amendments to the disclosure requirements during the first quarter of fiscal 2021. This amendment did not have an impact on our consolidated financial statements as this amendment simplifies the financial disclosures required in our guarantor and non-guarantor financial information. See Part I, Item 2, Management’s Discussion and Analysis of Financial Condition and Results of Operations—Supplemental Guarantor Financial Information. The Company has implemented all new accounting pronouncements that are in effect and that may impact its financial statements, and does not believe that there are any other new accounting pronouncements that have been issued that might have a material impact on its financial position or results of operations.

INVENTORIES (Tables)

INVENTORIES (Tables)	6 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory	The following table details the components of inventory: At March 31, 2021 At September 30, 2020 Raw materials and supplies $ 155,720 $ 146,351 Work in process 86,299 83,697 Finished goods 242,734 183,777 Total $ 484,753 $ 413,825

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	6 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Summary of Property, Plant and Equipment	The following table details the components of property, plant and equipment, net: At March 31, 2021 At September 30, 2020 Land, building and building improvements $ 169,081 $ 167,005 Machinery and equipment 611,187 595,126 Leasehold improvements 53,952 53,386 834,220 815,517 Accumulated depreciation and amortization (493,215) (471,553) Total $ 341,005 $ 343,964

CREDIT LOSSES (Tables)

CREDIT LOSSES (Tables)	6 Months Ended
	Mar. 31, 2021
Credit Loss [Abstract]
Schedule of Accounts Receivable, Allowance for Credit Losses	The following table provides a roll-forward of the allowance for credit losses that is deducted from the amortized cost basis of accounts receivable to present the net amount expected to be collected: Beginning Balance, October 1, 2020 $ 8,505 Provision for expected credit losses 1,228 Amounts written off charged against the allowance (161) Other, primarily foreign currency translation 22 Ending Balance, March 31, 2021 $ 9,594

GOODWILL AND OTHER INTANGIBLES

GOODWILL AND OTHER INTANGIBLES (Tables)	6 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Changes in Carrying Value of Goodwill	The following table provides changes in the carrying value of goodwill by segment during the six months ended March 31, 2021: At September 30, 2020 Business Acquisitions (a) Business Divestitures (b) Foreign At March 31, 2021 Consumer and Professional Products $ 232,845 $ 1,246 $ — $ 3,287 $ 237,378 Home and Building Products 191,253 — — — 191,253 Defense Electronics 18,545 — (811) — 17,734 Total $ 442,643 $ 1,246 $ (811) $ 3,287 $ 446,365 (a) The increase in the CPP segment was due to the acquisition of Quatro. (b) The decrease in the DE segment was due to the divestiture of SEG.
Summary of Gross Carrying Value and Accumulated Amortization of Intangible Assets	The following table provides the gross carrying value and accumulated amortization for each major class of intangible assets: At March 31, 2021 At September 30, 2020 Gross Carrying Amount Accumulated Average Gross Carrying Amount Accumulated Customer relationships & other $ 189,189 $ 71,840 23 $ 185,940 $ 66,656 Technology and patents 19,529 8,030 13 19,464 8,360 Total amortizable intangible assets 208,718 79,870 205,404 75,016 Trademarks 228,658 — 224,640 — Total intangible assets $ 437,376 $ 79,870 $ 430,044 $ 75,016

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	6 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Summary of Long-Term Debt	At March 31, 2021 At September 30, 2020 Outstanding Balance Original Issuer Premium Capitalized Fees & Expenses Balance Sheet Coupon Interest Rate Outstanding Balance Original Issuer Premium Capitalized Fees & Expenses Balance Sheet Coupon Interest Rate Senior notes due 2028 (a) $ 1,000,000 $ 339 (14,329) $ 986,010 5.75 % $ 1,000,000 $ 363 $ (15,376) $ 984,987 5.75 % Revolver due 2025 (b) 20,622 — (1,963) 18,659 Variable 12,858 — (2,209) 10,649 Variable Finance lease - real estate (c) 15,924 — (17) 15,907 5.60 % 17,218 — (30) 17,188 5.60 % Non US lines of credit (d) 4,405 — (24) 4,381 Variable — — (30) (30) Variable Non US term loans (d) 29,870 — (133) 29,737 Variable 31,086 — (160) 30,926 Variable Other long term debt (e) 4,094 — (16) 4,078 Variable 3,260 — (16) 3,244 Variable Totals 1,074,915 339 (16,482) 1,058,772 1,064,422 363 (17,821) 1,046,964 less: Current portion (14,913) — — (14,913) (9,922) — — (9,922) Long-term debt $ 1,060,002 $ 339 $ (16,482) $ 1,043,859 $ 1,054,500 $ 363 $ (17,821) $ 1,037,042
Summary of Interest Expense Incurred	Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 Effective Interest Rate Cash Interest Amort. Debt Amort. Debt Issuance Costs Total Interest Expense Effective Interest Rate Cash Interest Amort. Debt Amort. Total Interest Expense Senior notes due 2028 (a) 6.0 % $ 14,375 $ 12 $ 505 $ 14,892 6.0 % $ 5,566 $ — $ 135 $ 5,701 Senior notes due 2022 (a) — — — — — 5.7 % 8,040 45 628 8,713 Revolver due 2025 (b) Variable 287 — 122 409 Variable 1,819 — 165 1,984 Finance lease - real estate (c) 5.9 % 224 — 7 231 6.1 % 52 — 7 59 Non US lines of credit (d) Variable 4 — 4 8 Variable 3 — 8 11 Non US term loans (d) Variable 163 — 18 181 Variable 292 — 7 299 Other long term debt (e) Variable 115 — 1 116 Variable 132 — — 132 Capitalized interest (6) — — (6) (28) — — (28) Totals $ 15,162 $ 12 $ 657 $ 15,831 $ 15,876 $ 45 $ 950 $ 16,871 Six Months Ended March 31, 2021 Six Months Ended March 31, 2020 Effective Interest Rate Cash Interest Amort. Debt Amort. Debt Issuance Costs & Other Fees Total Interest Expense Effective Interest Rate Cash Interest Amort. Debt Premium Amort. Debt Issuance Costs & Other Fees Total Interest Expense Senior notes due 2028 (a) 6.0 % $ 28,750 $ 24 $ 1,023 $ 29,797 6.0 % $ 5,566 $ — $ 135 $ 5,701 Senior notes due 2022 (a) — — — — — 5.7 % 21,165 112 1,579 22,856 Revolver due 2025 (b) Variable 416 — 245 661 Variable 3,201 — 397 3,598 Finance lease - real estate (c) 5.6 % 456 — 13 469 6.0 % 113 — 13 126 Non US lines of credit (d) Variable 7 — 8 15 Variable 7 — 12 19 Non US term loans (d) Variable 334 — 35 369 Variable 564 — 19 583 Other long term debt (e) Variable 222 — 1 223 Variable 292 — — 292 Capitalized interest (13) — — (13) (93) — — (93) Totals $ 30,172 $ 24 $ 1,325 $ 31,521 $ 30,815 $ 112 $ 2,155 $ 33,082

SHAREHOLDERS' EQUITY SHAREHOLDE

SHAREHOLDERS' EQUITY SHAREHOLDERS' EQUITY (Tables)	6 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Compensation Expense Relating to Stock-based Incentive Plans	The following table summarizes the Company’s compensation expense relating to all stock-based incentive plans: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Restricted stock $ 4,349 $ 3,662 $ 7,777 $ 6,812 ESOP 944 658 1,724 1,490 Total stock based compensation $ 5,293 $ 4,320 $ 9,501 $ 8,302

EARNINGS PER SHARE (EPS) (Table

EARNINGS PER SHARE (EPS) (Tables)	6 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Summary of Reconciliation of Share Amounts Used in Earnings Per Share	The following table is a reconciliation of the share amounts (in thousands) used in computing earnings per share: Three Months Ended March 31, Six Months Ended March 31, 2021 2020 2021 2020 Common shares outstanding 56,684 47,431 56,684 47,431 Unallocated ESOP shares (1,961) (2,159) (1,961) (2,159) Non-vested restricted stock (3,822) (3,562) (3,822) (3,562) Impact of weighted average shares (63) (145) (184) (341) Weighted average shares outstanding - basic 50,838 41,565 50,717 41,369 Incremental shares from stock based compensation 2,426 2,169 2,494 2,457 Weighted average shares outstanding - diluted 53,264 43,734 53,211 43,826

BUSINESS SEGMENTS (Tables)

BUSINESS SEGMENTS (Tables)	6 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Summary of Reportable Segments from Continuing Operations	Information on Griffon’s reportable segments is as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, REVENUE 2021 2020 2021 2020 Consumer and Professional Products $ 331,871 $ 274,912 $ 622,913 $ 515,988 Home and Building Products 242,811 209,829 493,292 451,210 Defense Electronics 60,150 81,609 127,918 147,590 Total consolidated net sales $ 634,832 $ 566,350 $ 1,244,123 $ 1,114,788 For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Segment adjusted EBITDA: Consumer and Professional Products $ 37,423 $ 25,027 $ 70,136 $ 46,953 Home and Building Products 40,060 30,635 88,429 71,336 Defense Electronics 2,220 4,248 7,805 8,723 Segment adjusted EBITDA 79,703 59,910 166,370 127,012 Unallocated amounts, excluding depreciation * (11,922) (11,947) (23,949) (23,889) Adjusted EBITDA 67,781 47,963 142,421 103,123 Net interest expense (15,527) (16,561) (31,172) (32,511) Depreciation and amortization (15,883) (15,719) (31,149) (31,544) Loss from debt extinguishment — (6,690) — (6,690) Restructuring charges (7,562) (3,104) (18,362) (9,538) Acquisition costs — (2,960) — (2,960) Gain (adjustment) on sale of SEG business (949) — 5,291 — Income before taxes $ 27,860 $ 2,929 $ 67,029 $ 19,880 * Unallocated amounts typically include general corporate expenses not attributable to a reportable segment. For the Three Months Ended March 31, For the Six Months Ended March 31, DEPRECIATION and AMORTIZATION 2021 2020 2021 2020 Segment: Consumer and Professional Products $ 8,620 $ 8,222 $ 16,819 $ 16,453 Home and Building Products 4,379 4,668 8,720 9,468 Defense Electronics 2,734 2,676 5,410 5,320 Total segment depreciation and amortization 15,733 15,566 30,949 31,241 Corporate 150 153 200 303 Total consolidated depreciation and amortization $ 15,883 $ 15,719 $ 31,149 $ 31,544 CAPITAL EXPENDITURES Segment: Consumer and Professional Products $ 6,813 $ 3,800 $ 13,720 $ 7,532 Home and Building Products 1,998 3,556 4,113 11,495 Defense Electronics 3,247 1,921 6,151 3,210 Total segment 12,058 9,277 23,984 22,237 Corporate 2 70 2 282 Total consolidated capital expenditures $ 12,060 $ 9,347 $ 23,986 $ 22,519 ASSETS At March 31, 2021 At September 30, 2020 Segment assets: Consumer and Professional Products $ 1,408,545 $ 1,255,127 Home and Building Products 604,325 606,785 Defense Electronics 288,019 329,128 Total segment assets 2,300,889 2,191,040 Corporate 216,571 248,902 Total continuing assets 2,517,460 2,439,942 Assets of discontinued operations 6,820 8,497 Consolidated total $ 2,524,280 $ 2,448,439
Summary of Disaggregation of Revenue by End Market and Segment	The following table presents revenue disaggregated by end market and segment: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Residential repair and remodel $ 50,560 $ 40,505 $ 96,160 $ 75,595 Retail 153,746 144,904 292,994 264,524 Residential new construction 14,540 14,884 28,055 29,857 Industrial 9,958 10,535 19,489 21,158 International excluding North America 103,067 64,084 186,215 124,854 Total Consumer and Professional Products 331,871 274,912 622,913 515,988 Residential repair and remodel 120,827 100,808 246,942 222,805 Commercial construction 94,751 86,300 190,690 178,187 Residential new construction 27,233 22,721 55,660 50,218 Total Home and Building Products 242,811 209,829 493,292 451,210 U.S. Government 35,045 53,623 82,369 96,324 International 21,497 25,021 38,392 43,554 Commercial 3,608 2,965 7,157 7,712 Total Defense Electronics 60,150 81,609 127,918 147,590 Total Consolidated Revenue $ 634,832 $ 566,350 $ 1,244,123 $ 1,114,788 The following table presents revenue disaggregated by geography based on the location of the Company's customer: For the Three Months Ended March 31, 2021 2020 CPP HBP DE Total CPP HBP DE Total United States $ 205,368 $ 230,955 $ 34,166 $ 470,489 $ 191,412 $ 199,060 $ 55,071 $ 445,543 Europe 38,965 41 5,791 44,797 24,737 5 9,880 34,622 Canada 21,778 9,797 1,925 33,500 17,515 7,867 4,209 29,591 Australia 63,691 — 122 63,813 39,032 — 189 39,221 All other countries 2,069 2,018 18,146 22,233 2,216 2,897 12,260 17,373 Consolidated revenue $ 331,871 $ 242,811 $ 60,150 $ 634,832 $ 274,912 $ 209,829 $ 81,609 $ 566,350 For the Six Months Ended March 31, 2021 2020 CPP HBP DE Total CPP HBP DE Total United States $ 388,810 $ 467,486 $ 81,544 $ 937,840 $ 351,570 $ 426,010 $ 101,214 $ 878,794 Europe 52,121 41 12,696 64,858 31,342 28 15,865 47,235 Canada 43,893 21,285 3,754 68,932 35,296 19,120 6,783 61,199 Australia 133,231 — 441 133,672 93,260 — 795 94,055 All other countries 4,858 4,480 29,483 38,821 4,520 6,052 22,933 33,505 Consolidated revenue $ 622,913 $ 493,292 $ 127,918 $ 1,244,123 $ 515,988 $ 451,210 $ 147,590 $ 1,114,788

EMPLOYEE BENEFIT PLANS (Tables)

EMPLOYEE BENEFIT PLANS (Tables)	6 Months Ended
	Mar. 31, 2021
Retirement Benefits [Abstract]
Summary of Defined Benefit Plans Included in Other Income	Defined benefit pension expense (income) included in Other Income (Expense), net was as follows: Three Months Ended March 31, Six Months Ended March 31, 2021 2020 2021 2020 Interest cost $ 745 $ 1,151 $ 1,489 $ 2,302 Expected return on plan assets (2,545) (2,586) (5,089) (5,172) Amortization: Prior service cost — 4 — 8 Recognized actuarial loss 1,573 1,042 3,146 2,084 Net periodic expense (income) $ (227) $ (389) $ (454) $ (778)

DISCONTINUED OPERATIONS (Tables

DISCONTINUED OPERATIONS (Tables)	6 Months Ended
	Mar. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	The following amounts summarize the total assets and liabilities related to the Installation Services and other discontinued activities which have been segregated from Griffon’s continuing operations, and are reported as assets and liabilities of discontinued operations in the Condensed Consolidated Balance Sheets: At March 31, 2021 At September 30, 2020 Assets of discontinued operations: Prepaid and other current assets $ 1,525 $ 2,091 Other long-term assets 5,295 6,406 Total assets of discontinued operations $ 6,820 $ 8,497 Liabilities of discontinued operations: Accrued liabilities, current $ 4,600 $ 3,797 Other long-term liabilities 6,415 7,014 Total liabilities of discontinued operations $ 11,015 $ 10,811

RESTRUCTURING CHARGES RESTRUCTU

RESTRUCTURING CHARGES RESTRUCTURING CHARGES (Tables)	6 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
Summary of the Restructuring and Other Related Charges	A summary of the restructuring and other related charges included in Cost of goods and services and SG&A expenses in the Company's Condensed Consolidated Statements of Operations were as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Cost of goods and services $ 3,337 $ 1,353 $ 9,762 $ 4,076 Selling, general and administrative expenses 4,225 1,751 8,600 5,462 Total restructuring charges $ 7,562 $ 3,104 $ 18,362 $ 9,538 For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Personnel related costs $ 782 $ 1,658 $ 3,264 $ 3,792 Facilities, exit costs and other 4,283 914 6,807 1,054 Non-cash facility and other 2,497 532 8,291 4,692 Total $ 7,562 $ 3,104 $ 18,362 $ 9,538
Summary of Accrued Liability for the Restructuring and Related Charges	The following table summarizes the accrued liabilities of the Company's restructuring actions: Cash Charges Non-Cash Personnel related costs Facilities & Facility and Other Costs Total Accrued liability at September 30, 2020 $ 2,701 $ 264 $ — $ 2,965 Q1 Restructuring charges 2,482 2,524 5,794 10,800 Q1 Cash payments (1,598) (2,534) — (4,132) Q1 Non-cash charges — — (5,794) (5,794) Accrued liability at December 31, 2020 $ 3,585 $ 254 $ — $ 3,839 Q2 Restructuring charges 782 4,283 2,497 7,562 Q2 Cash payments (3,840) (4,273) — (8,113) Q2 Non-cash charges — — (2,497) (2,497) Accrued liability at March 31, 2021 $ 527 $ 264 $ — $ 791

WARRANTY LIABILITY (Tables)

WARRANTY LIABILITY (Tables)	6 Months Ended
	Mar. 31, 2021
Product Warranties Disclosures [Abstract]
Summary of Changes in Warranty Liability, Included in Accrued Liabilities	Changes in Griffon’s warranty liability, included in Accrued liabilities, were as follows: Three Months Ended March 31, Six Months Ended March 31, 2021 2020 2021 2020 Balance, beginning of period $ 10,834 $ 7,344 $ 10,843 $ 7,894 Warranties issued and changes in estimated pre-existing warranties 6,477 4,862 11,216 8,227 Actual warranty costs incurred (4,633) (4,417) (9,381) (8,332) Balance, end of period $ 12,678 $ 7,789 $ 12,678 $ 7,789

OTHER COMPREHENSIVE INCOME (L_2

OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	6 Months Ended
	Mar. 31, 2021
OCI, Net of Tax [Abstract]
Summary of Comprehensive Income (Loss)	The amounts recognized in other comprehensive income (loss) were as follows: For the Three Months Ended March 31, 2021 2020 Pre-tax Tax Net of tax Pre-tax Tax Net of tax Foreign currency translation adjustments $ 1,739 $ — $ 1,739 $ (16,471) $ — $ (16,471) Pension and other defined benefit plans 1,585 (340) 1,245 847 (178) 669 Cash flow hedges 2,559 (768) 1,791 1,383 (415) 968 Total other comprehensive income (loss) $ 5,883 $ (1,108) $ 4,775 $ (14,241) $ (593) $ (14,834) For the Six Months Ended March 31, 2021 2020 Pre-tax Tax Net of tax Pre-tax Tax Net of tax Foreign currency translation adjustments $ 13,862 $ — $ 13,862 $ (10,001) $ — $ (10,001) Pension and other defined benefit plans 3,735 (784) 2,951 1,694 (353) 1,341 Cash flow hedges 1,576 (473) 1,103 953 (286) 667 Total other comprehensive income (loss) $ 19,173 $ (1,257) $ 17,916 $ (7,354) $ (639) $ (7,993) The components of Accumulated other comprehensive income (loss) are as follows: At March 31, 2021 At September 30, 2020 Foreign currency translation adjustments $ (11,821) $ (25,683) Pension and other defined benefit plans (43,647) (46,598) Change in Cash flow hedges 1,292 189 $ (54,176) $ (72,092)
Reclassification from Accumulated Other Comprehensive Income (Loss)	Amounts reclassified from accumulated other comprehensive income (loss) to income were as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, Gain (Loss) 2021 2020 2021 2020 Pension amortization $ (1,573) $ (1,046) $ (3,146) $ (2,092) Cash flow hedges (1,741) 1,050 (2,399) 994 Total gain (loss) $ (3,314) $ 4 (5,545) (1,098) Tax benefit (expense) 696 (1) 1,165 231 Total $ (2,618) $ 3 $ (4,380) $ (867)

LEASES (Tables)

LEASES (Tables)	6 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Components of Operating Lease Cost, Cash Flow Information, and Average Lease Terms and Discount Rates	Components of operating lease costs are as follows: For the Three Months Ended March 31, For the Six Months Ended March 31, 2021 2020 2021 2020 Fixed $ 9,970 $ 9,187 $ 20,010 $ 18,739 Variable (a), (b) 2,087 1,823 4,134 3,576 Short-term (b) 1,053 1,393 2,167 2,823 Total $ 13,110 $ 12,403 $ 26,311 $ 25,138 (a) Primarily relates to common-area maintenance and property taxes. (b) Not recorded on the balance sheet. Supplemental cash flow information were as follows: For the Six Months Ended March 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 22,099 $ 21,582 Financing cash flows from finance leases 1,865 1,940 Total $ 23,964 $ 23,522 Average lease terms and discount rates at March 31, 2021 were as follows: Weighted-average remaining lease term (years) Operating leases 8.1 Finance Leases 8.2 Weighted-average discount rate Operating Leases 4.45 % Finance Leases 5.50 %
Supplemental Condensed Consolidated Balance Sheet Information	Supplemental Condensed Consolidated Balance Sheet information related to leases were as follows: March 31, 2021 September 30, 2020 Operating Leases: Right of use assets: Operating right-of-use assets $ 154,929 $ 161,627 Lease Liabilities: Current portion of operating lease liabilities $ 30,685 $ 31,848 Long-term operating lease liabilities 128,714 136,054 Total operating lease liabilities $ 159,399 $ 167,902 Finance Leases: Property, plant and equipment, net (1) $ 18,068 $ 18,774 Lease Liabilities: Notes payable and current portion of long-term debt $ 3,110 $ 3,352 Long-term debt, net 14,950 15,339 Total financing lease liabilities $ 18,060 $ 18,691 (1) Finance lease assets are recorded net of accumulated depreciation of $4,296 and $2,383 as of March 31, 2021 and September 30, 2020, respectively.
Aggregate Future Maturities of Lease Payments for Operating Leases	The aggregate future maturities of lease payments for operating leases and finance leases as of March 31, 2021 are as follows (in thousands): Operating Leases Finance Leases 2020 (a) $ 19,128 $ 2,381 2021 34,484 3,087 2022 26,884 2,749 2023 20,180 2,195 2024 18,214 2,077 2025 12,376 2,075 Thereafter 63,859 7,777 Total lease payments 195,125 22,341 Less: Imputed Interest (35,726) (4,281) Present value of lease liabilities $ 159,399 $ 18,060 (a) Excluding the six months ended March 31, 2021.
Aggregate Future Maturities of Lease Payments for Finance Leases	The aggregate future maturities of lease payments for operating leases and finance leases as of March 31, 2021 are as follows (in thousands): Operating Leases Finance Leases 2020 (a) $ 19,128 $ 2,381 2021 34,484 3,087 2022 26,884 2,749 2023 20,180 2,195 2024 18,214 2,077 2025 12,376 2,075 Thereafter 63,859 7,777 Total lease payments 195,125 22,341 Less: Imputed Interest (35,726) (4,281) Present value of lease liabilities $ 159,399 $ 18,060 (a) Excluding the six months ended March 31, 2021.

DESCRIPTION OF BUSINESS AND B_3

DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Details)	6 Months Ended
	Mar. 31, 2021segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	3

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2021USD ($)$ / shares
Designated as Hedging Instrument | Australian Dollar Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, notional amount	$ 61,000	$ 61,000
Contracts weighted average rate price (in dollars per share) | $ / shares		$ 1.29
Deferred gain (loss) from currency translation included in AOCI	(831)	$ (831)
Deferred gain (loss) from currency translation included in AOCI, net of tax	(582)	(582)
Designated as Hedging Instrument | Australian Dollar Forward Contracts | Cost of goods and services
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) reclassified for settled contracts	(1,741)	$ (2,399)
Designated as Hedging Instrument | Australian Dollar Forward Contracts | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts duration		30 days
Designated as Hedging Instrument | Australian Dollar Forward Contracts | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts duration		180 days
Not Designated as Hedging Instrument | Canadian Dollar Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, notional amount	$ 7,935	$ 7,935
Derivative, average forward exchange rate	1.30	1.30
Not Designated as Hedging Instrument | Canadian Dollar Forward Contracts | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts duration		29 days
Not Designated as Hedging Instrument | Canadian Dollar Forward Contracts | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts duration		450 days
Not Designated as Hedging Instrument | British Pound Forward Contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, notional amount	$ 5,200	$ 5,200
Derivative, average forward exchange rate	0.75	0.75
Not Designated as Hedging Instrument | British Pound Forward Contracts | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts duration		6 days
Not Designated as Hedging Instrument | British Pound Forward Contracts | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency contracts duration		104 days
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Insurance contracts fair value	$ 3,821	$ 3,821
Fair Value, Inputs, Level 2 | Not Designated as Hedging Instrument | Canadian Dollar Forward Contracts | Other income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on foreign currency derivative instruments not designated as hedging instruments	(520)	244
Realized gains (losses)	(102)	(161)
Fair Value, Inputs, Level 2 | Not Designated as Hedging Instrument | British Pound Forward Contracts | Other income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (loss) on foreign currency derivative instruments not designated as hedging instruments	386	141
Realized gains (losses)	(211)	(281)
Fair Value, Inputs, Level 2 | Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	2,088	2,088
Fair Value, Inputs, Level 2 | Portion at Other than Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	1,000	1,000
Senior notes due 2028 | Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior note, fair value disclosure	$ 1,060,000	$ 1,060,000

REVENUE - Narrative (Details)

REVENUE - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020
Concentration Risk [Line Items]
Net favorable (unfavorable) catch-up adjustments to income from operations	$ 1,423	$ 2,188	$ 3,220	$ 422
Accumulated estimated costs to complete loss contracts	$ 8,500		$ 8,500		$ 10,800
Customer Concentration Risk | CPP and HBP
Concentration Risk [Line Items]
Percentage of performance obligations recognized at a point in time			86.00%
Revenue from Contract with Customer Benchmark | Government Contracts Concentration Risk | Transferred over Time
Concentration Risk [Line Items]
Concentration risk (in percentage)			14.00%

REVENUE - Transaction Price All

REVENUE - Transaction Price Allocated to the Remaining Performance Obligations (Details) $ in Thousands	Mar. 31, 2021USD ($)
Revenue from Contract with Customer [Abstract]
Remaining performance obligations (backlog)	$ 353,870
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations (backlog), percentage to be satisfied within one year	65.00%
Remaining performance obligations (backlog), expected timing of satisfaction, period	12 months

REVENUE - Contract Balances (De

REVENUE - Contract Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Contract costs and recognized income not yet billed, net of progress payments	$ 75,000	$ 84,426
Increase (decrease) in contract assets balance	(9,426)
Contract costs and recognized income not yet billed, noncurrent	7,700	7,500
Contract liabilities	22,964	$ 24,386
Increase (decrease) in contract liabilities	$ (1,422)

ACQUISITIONS AND DISPOSITIONS -

ACQUISITIONS AND DISPOSITIONS - Acquisitions (Details) £ in Thousands, $ in Thousands, $ in Thousands	Dec. 22, 2020USD ($)	Dec. 22, 2020AUD ($)	Nov. 29, 2019USD ($)	Nov. 29, 2019GBP (£)	Mar. 31, 2020USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2021USD ($)	Dec. 22, 2020AUD ($)	Sep. 30, 2020USD ($)
Business Acquisition [Line Items]
Goodwill | $							$ 446,365		$ 442,643
Acquisition costs | $					$ 2,960	$ 2,960
Quatro Design Pty Ltd
Business Acquisition [Line Items]
Cash payment to acquire business	$ 2,700	$ 3,500
Additional contingent consideration	760							$ 1,000
Intangible assets	2,082							2,755
Goodwill	$ 1,246							$ 1,648
Vatre Group Limited
Business Acquisition [Line Items]
Intangible assets				£ 3,454
Goodwill				£ 3,449
Percentage of outstanding stock acquired				100.00%
Business combination, consideration transferred			$ 10,500	£ 8,750
Inventory				2,914
Accounts receivable and other assets				2,492
Accounts payable and accrued liabilities				£ 3,765

ACQUISITIONS AND DISPOSITIONS_2

ACQUISITIONS AND DISPOSITIONS - Dispositions (Details) - Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations - Systems Engineering Group, Inc. - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2020	Mar. 31, 2021	Sep. 30, 2020	Dec. 18, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received from business dispositions				$ 15,000
Revenue from disposed business	$ 7,000		$ 31,000
Gain (adjustment) on sale of SEG business		$ 5,291
Gain, net of tax, from business dispositions		$ 5,251
Gain per share from business dispositions		$ 0.10

INVENTORIES - Summary of Invent

INVENTORIES - Summary of Inventories Stated at Lower Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 155,720	$ 146,351
Work in process	86,299	83,697
Finished goods	242,734	183,777
Total	$ 484,753	$ 413,825

PROPERTY, PLANT AND EQUIPMENT -

PROPERTY, PLANT AND EQUIPMENT - Summary of Property Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	$ 834,220	$ 815,517
Accumulated depreciation and amortization	(493,215)	(471,553)
Total	341,005	343,964
Land, building and building improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	169,081	167,005
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	611,187	595,126
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment gross	$ 53,952	$ 53,386

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 13,450	$ 13,316	$ 26,338	$ 26,748
Selling, general and administrative expenses
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 5,014	$ 4,910	$ 9,720	$ 9,861

CREDIT LOSSES (Details)

CREDIT LOSSES (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2021USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance, October 1, 2020	$ 8,505
Provision for expected credit losses	1,228
Amounts written off charged against the allowance	(161)
Other, primarily foreign currency translation	22
Ending Balance, March 31, 2021	$ 9,594

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLES - Summary of Changes in Carrying Value of Goodwill (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2021USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 442,643
Business Acquisitions	1,246
Business Divestitures	(811)
Foreign currency translations adjustments	3,287
Goodwill, ending balance	446,365
Consumer and Professional Products
Goodwill [Roll Forward]
Goodwill, beginning balance	232,845
Business Acquisitions	1,246
Business Divestitures	0
Foreign currency translations adjustments	3,287
Goodwill, ending balance	237,378
Home and Building Products
Goodwill [Roll Forward]
Goodwill, beginning balance	191,253
Business Acquisitions	0
Business Divestitures	0
Foreign currency translations adjustments	0
Goodwill, ending balance	191,253
Defense Electronics
Goodwill [Roll Forward]
Goodwill, beginning balance	18,545
Business Acquisitions	0
Business Divestitures	(811)
Foreign currency translations adjustments	0
Goodwill, ending balance	$ 17,734

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLES - Summary of Gross Carrying Value and Accumulated Amortization of Intangible Assets (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 208,718	$ 205,404
Accumulated Amortization	79,870	75,016
Trademarks	228,658	224,640
Total intangible assets	437,376	430,044
Customer relationships & other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	189,189	185,940
Accumulated Amortization	$ 71,840	66,656
Average Life (Years)	23 years
Technology and patents
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 19,529	19,464
Accumulated Amortization	$ 8,030	$ 8,360
Average Life (Years)	13 years

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLES - Narrative (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)unit
Goodwill and Intangible Assets Disclosure [Abstract]
Carry amount of intangible assets related to foreign currency translation	$ 5,250,000
Amortization expense	2,433,000	$ 2,403,000	$ 4,811,000	$ 4,796,000
Estimated amortization expense, remainder of fiscal year	4,574,000		4,574,000
Estimated amortization expense, year one	9,376,000		9,376,000
Estimated amortization expense, year two	9,224,000		9,224,000
Estimated amortization expense, year three	9,198,000		9,198,000
Estimated amortization expense, year four	9,198,000		9,198,000
Estimated amortization expense, year five	9,198,000		9,198,000
Estimated amortization expense, thereafter	$ 78,080,000		78,080,000
Number of reporting units for goodwill impairment testing | unit				3
Goodwill impairment			0
Indefinite-lived intangible asset (excluding goodwill) impairment			$ 0

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 10,748	$ 2,034	$ 20,417	$ 8,373
Income before taxes	27,860	2,929	67,029	19,880
Restructuring charges	7,562	3,104	18,362	9,538
Restructuring charges, net of tax	5,651	3,005	13,951	7,153
Effective income tax rate reconciliation, disposition of business	949		(5,291)
Effective income tax rate reconciliation, disposition of business, net of tax	766		(5,251)
Other tax expense (benefit) that affect comparability	$ 1,913	(1,413)	$ (115)	(580)
Effective income tax rate reconciliation, acquisition cost		2,960		2,960
Effective income tax rate reconciliation, acquisition cost, net of tax		2,321		2,321
Effective income tax rate reconciliation, debt extinguishment loss		6,690		6,690
Effective income tax rate reconciliation, debt extinguishment loss, net of tax		$ 5,245		$ 5,245
Effective tax rate	30.00%	35.90%	31.10%	34.40%

LONG-TERM DEBT - Summary of Lon

LONG-TERM DEBT - Summary of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020	Jun. 22, 2020	Feb. 19, 2020
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	$ 1,074,915	$ 1,064,422
less: Current portion, Outstanding Balance	(14,913)	(9,922)
Long-term debt, Outstanding Balance, Non-current	1,060,002	1,054,500
Original Issuer Premium	339	363
less: Current portion, Original Issuer Premium	0	0
Long-term debt, Original Issuer Premium, Non-current	339	363
Capitalized Fees & Expenses	(16,482)	(17,821)
Long-term debt, Balance Sheet	1,058,772	1,046,964
less: Current portion, Balance Sheet	(14,913)	(9,922)
Long-term debt, Balance Sheet, Non-current	1,043,859	1,037,042
Senior notes due 2028
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	1,000,000	1,000,000
Original Issuer Premium	339	363
Capitalized Fees & Expenses	(14,329)	(15,376)
Long-term debt, Balance Sheet	$ 986,010	$ 984,987
Coupon Interest Rate	5.75%	5.75%	5.75%	5.75%
Revolver due 2025
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	$ 20,622	$ 12,858
Original Issuer Premium	0	0
Capitalized Fees & Expenses	(1,963)	(2,209)
Long-term debt, Balance Sheet	18,659	10,649
Finance lease - real estate
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	15,924	17,218
Original Issuer Premium	0	0
Capitalized Fees & Expenses	(17)	(30)
Long-term debt, Balance Sheet	$ 15,907	$ 17,188
Coupon Interest Rate	5.60%	5.60%
Non US lines of credit
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	$ 4,405	$ 0
Original Issuer Premium	0	0
Capitalized Fees & Expenses	(24)	(30)
Long-term debt, Balance Sheet	4,381	(30)
Non US term loans
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	29,870	31,086
Original Issuer Premium	0	0
Capitalized Fees & Expenses	(133)	(160)
Long-term debt, Balance Sheet	29,737	30,926
Other long term debt
Debt Instrument [Line Items]
Long-term debt, Outstanding Balance	4,094	3,260
Original Issuer Premium	0	0
Capitalized Fees & Expenses	(16)	(16)
Long-term debt, Balance Sheet	$ 4,078	$ 3,244

LONG-TERM DEBT - Summary of Int

LONG-TERM DEBT - Summary of Interest Expense Incurred (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Debt Instrument [Line Items]
Cash Interest, Capitalized Interest	$ (6)	$ (28)	$ (13)	$ (93)
Cash Interest	15,162	15,876	30,172	30,815
Amort. Debt Premium	12	45	24	112
Amort. Debt Issuance Costs & Other Fees	657	950	1,325	2,155
Total Interest Expense	$ 15,831	$ 16,871	$ 31,521	$ 33,082
Senior notes due 2028
Debt Instrument [Line Items]
Effective Interest Rate	6.00%	6.00%	6.00%	6.00%
Cash Interest, Including Amounts Capitalized	$ 14,375	$ 5,566	$ 28,750	$ 5,566
Amort. Debt Premium	12	0	24	0
Amort. Debt Issuance Costs & Other Fees	505	135	1,023	135
Total Interest Expense	14,892	$ 5,701	29,797	$ 5,701
Senior notes due 2022
Debt Instrument [Line Items]
Effective Interest Rate		5.70%		5.70%
Cash Interest, Including Amounts Capitalized	0	$ 8,040	0	$ 21,165
Amort. Debt Premium	0	45	0	112
Amort. Debt Issuance Costs & Other Fees	0	628	0	1,579
Total Interest Expense	0	8,713	0	22,856
Revolver due 2025
Debt Instrument [Line Items]
Cash Interest, Including Amounts Capitalized	287	1,819	416	3,201
Amort. Debt Premium	0	0	0	0
Amort. Debt Issuance Costs & Other Fees	122	165	245	397
Total Interest Expense	$ 409	$ 1,984	$ 661	$ 3,598
Finance lease - real estate
Debt Instrument [Line Items]
Effective Interest Rate	5.90%	6.10%	5.60%	6.00%
Cash Interest, Including Amounts Capitalized	$ 224	$ 52	$ 456	$ 113
Amort. Debt Premium	0	0	0	0
Amort. Debt Issuance Costs & Other Fees	7	7	13	13
Total Interest Expense	231	59	469	126
Non US lines of credit
Debt Instrument [Line Items]
Cash Interest, Including Amounts Capitalized	4	3	7	7
Amort. Debt Premium	0	0	0	0
Amort. Debt Issuance Costs & Other Fees	4	8	8	12
Total Interest Expense	8	11	15	19
Non US term loans
Debt Instrument [Line Items]
Cash Interest, Including Amounts Capitalized	163	292	334	564
Amort. Debt Premium	0	0	0	0
Amort. Debt Issuance Costs & Other Fees	18	7	35	19
Total Interest Expense	181	299	369	583
Other long term debt
Debt Instrument [Line Items]
Cash Interest, Including Amounts Capitalized	115	132	222	292
Amort. Debt Premium	0	0	0	0
Amort. Debt Issuance Costs & Other Fees	1	0	1	0
Total Interest Expense	$ 116	$ 132	$ 223	$ 292

LONG-TERM DEBT - Narrative (Det

LONG-TERM DEBT - Narrative (Details) $ in Thousands	Jun. 22, 2020USD ($)	Jul. 31, 2018GBP (£)	Jul. 31, 2016AUD ($)	Nov. 30, 2012CAD ($)	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2021USD ($)renewalOption	Mar. 31, 2020USD ($)	Sep. 30, 2020AUD ($)	Mar. 31, 2021CAD ($)	Mar. 31, 2021AUD ($)	Mar. 31, 2021GBP (£)	Sep. 30, 2020USD ($)	Sep. 30, 2020AUD ($)	Feb. 19, 2020USD ($)	Jan. 30, 2020USD ($)	Jan. 29, 2020USD ($)	Sep. 30, 2019AUD ($)	Jul. 31, 2016USD ($)	Jul. 31, 2016AUD ($)
Debt Instrument [Line Items]
Debt outstanding					$ 1,074,915,000		$ 1,074,915,000						$ 1,064,422,000
Loss from debt extinguishment					0	$ 6,690,000	0	$ 6,690,000
Basis spread on variable rate				1.30%
Mortgage loan balance					$ 1,058,772,000		$ 1,058,772,000						$ 1,046,964,000
Troy, Ohio
Debt Instrument [Line Items]
Percentage bearing fixed interest, percentage rate					5.00%		5.00%			5.00%	5.00%	5.00%
Ocala, Florida
Debt Instrument [Line Items]
Percentage bearing fixed interest, percentage rate					5.60%		5.60%			5.60%	5.60%	5.60%
Number of option to extend | renewalOption							2
Lease renewal term					5 years		5 years			5 years	5 years	5 years
Revolver due 2025
Debt Instrument [Line Items]
Maximum borrowing capacity																$ 400,000	$ 350,000,000
Maximum borrowing capacity, accordion feature																100,000,000
Maximum percentage of equity interest of subsidiaries borrowings guaranteed							65.00%
Long-term line of credit					$ 20,622,000		$ 20,622,000
Outstanding standby letters of credit					16,310,000		16,310,000
Remaining borrowing capacity					363,068,000		$ 363,068,000
Revolver due 2025 | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate							0.50%
Revolver due 2025 | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate							1.50%
Term Loan | Northcote Holdings Pty. Ltd
Debt Instrument [Line Items]
Face amount																				$ 29,625,000
Basis spread on variable rate			1.95%
Long-term line of credit					$ 10,192,000		$ 10,192,000				$ 13,375,000			$ 18,375,000				$ 23,375,000
Debt instrument, periodic payment, principal			$ 1,250,000
Periodic payment terms, balloon payment to be paid																				9,625,000
Debt instrument, interest rate, effective percentage					2.01%		2.01%			2.01%	2.01%	2.01%
Term loan balance change									$ 5,000,000
Term Loan | Ames UK
Debt Instrument [Line Items]
Face amount | £		£ 14,000,000
Debt instrument, periodic payment, principal | £		438,000
Periodic payment terms, balloon payment to be paid | £		£ 7,088,000
Mortgages | London Interbank Offered Rate (LIBOR) | Ames UK
Debt Instrument [Line Items]
Basis spread on variable rate		1.80%
Revolving Credit Facility | Northcote Holdings Pty. Ltd
Debt Instrument [Line Items]
Face amount																				$ 20,000,000
Basis spread on variable rate			1.90%
Mortgage loan balance					$ 0		$ 0
Debt instrument, interest rate, effective percentage					1.98%		1.98%			1.98%	1.98%	1.98%
Revolving Credit Facility | Ames UK
Debt Instrument [Line Items]
Face amount | £		£ 5,000,000
Basis spread on variable rate		1.50%
Mortgage loan balance					$ 4,405,000		$ 4,405,000					£ 3,204,000
Interest rate at period end					1.60%		1.60%			1.60%	1.60%	1.60%
Long-term line of credit, revolver outstanding balance					$ 0		$ 0
Term and Mortgage Loans | Ames UK
Debt Instrument [Line Items]
Mortgage loan balance					19,678,000		19,678,000					£ 14,313,000
Letter of Credit Subfacility | Revolver due 2025
Debt Instrument [Line Items]
Maximum borrowing capacity																100,000,000
Multicurrency Subfacility | Revolver due 2025
Debt Instrument [Line Items]
Maximum borrowing capacity																$ 200,000,000
Receivables Purchase Facility
Debt Instrument [Line Items]
Mortgage loan balance					$ 0		$ 0
Receivables Purchase Facility | Northcote Holdings Pty. Ltd
Debt Instrument [Line Items]
Face amount																			$ 10,000,000
Basis spread on variable rate			1.35%
Mortgage loan balance														$ 15,000,000				$ 10,000,000
Debt instrument, interest rate, effective percentage					1.41%		1.41%			1.41%	1.41%	1.41%
Increase in receivables purchase line									$ (5,000,000)
Senior notes due 2028
Debt Instrument [Line Items]
Face amount	$ 150,000,000														$ 850,000,000
Debt instrument, interest rate, stated percentage	5.75%				5.75%		5.75%			5.75%	5.75%	5.75%	5.75%	5.75%	5.75%
Debt instrument, issuance price (in percentage)	100.25%
Debt outstanding					$ 1,000,000,000		$ 1,000,000,000						$ 1,000,000,000
Capitalized fees and expenses					16,448,000		16,448,000
Mortgage loan balance					986,010,000		986,010,000						984,987,000
Senior notes due 2028 | Fair Value, Inputs, Level 1
Debt Instrument [Line Items]
Senior note, fair value disclosure					1,060,000,000		1,060,000,000
Senior notes due 2022
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	5.25%
Debt redeemed	$ 1,000,000,000
Loss from debt extinguishment					7,925,000
Write off of debt issuance costs					6,725,000
Tender offer net premium expense					607,000
Redemption interest expense					593,000
Senior Notes
Debt Instrument [Line Items]
Debt outstanding					1,000,000,000		1,000,000,000
ESOP Loans
Debt Instrument [Line Items]
Mortgage loan balance					28,608,000		28,608,000
Debt instrument, periodic payment, principal							$ 635,000
ESOP Loans | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate							2.91%
Non US lines of credit
Debt Instrument [Line Items]
Debt outstanding					4,405,000		$ 4,405,000						0
Remaining borrowing capacity					11,894,000		11,894,000			$ 15,000
Mortgage loan balance					$ 4,381,000		4,381,000						$ (30,000)
Proceeds from long-term lines of credit				$ 15,000			$ 11,894,000
Non US lines of credit | LIBOR Rate
Debt Instrument [Line Items]
Interest rate at period end					1.41%		1.41%			1.41%	1.41%	1.41%
Non US lines of credit | Bankers Acceptance Rate
Debt Instrument [Line Items]
Interest rate at period end					1.47%		1.47%			1.47%	1.47%	1.47%
Mortgages | Ames UK
Debt Instrument [Line Items]
Face amount | £		£ 4,000,000
Interest rate at period end					1.85%		1.85%			1.85%	1.85%	1.85%
Debt instrument, periodic payment, principal | £		105,000
Periodic payment terms, balloon payment to be paid | £		£ 2,349,000

SHAREHOLDERS' EQUITY - Narrativ

SHAREHOLDERS' EQUITY - Narrative (Details)

Apr. 29, 2021$ / shares

Jan. 30, 2020shares

Mar. 31, 2021USD ($)executive$ / sharesshares

Dec. 31, 2020USD ($)executive$ / sharesshares

Sep. 30, 2020$ / shares

Jun. 30, 2020$ / shares

Mar. 31, 2020$ / shares

Dec. 31, 2019$ / shares

Mar. 31, 2021USD ($)$ / sharesshares

Mar. 31, 2020$ / shares

Sep. 30, 2020$ / shares

Aug. 01, 2018USD ($)

Jan. 31, 2018shares

Aug. 03, 2016USD ($)

Class of Stock [Line Items]

Common stock, dividends, per share, cash paid (in dollars per share) | $ / shares

$ 0.08

$ 0.075

$ 0.16

$ 0.15

Stock repurchase program, authorized amount | $

$ 50,000,000

$ 50,000,000

Stock repurchase program, remaining authorized repurchase amount | $

$ 57,955,000

$ 57,955,000

Shares paid for tax withholding for share based compensation, value | $

$ 0

Restricted Stock and Restricted Stock Units

Class of Stock [Line Items]

Equity instruments other than options, grants in period (in shares)

511,624

Restricted Stock and Restricted Stock Units, Subject to Performance Conditions

Class of Stock [Line Items]

Award vesting period

3 years

Equity instruments other than options, grants in period (in shares)

226,811

Equity instruments other than options, granted in period, fair value | $

$ 5,500,000

Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) | $ / shares

$ 24.25

Restricted Stock and Restricted Stock Units, Subject to Performance Conditions | Executive Officer

Class of Stock [Line Items]

Equity instruments other than options, grants in period (in shares)

203,282

Equity instruments other than options, granted in period, fair value | $

$ 4,923,000

Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) | $ / shares

$ 24.22

Number of executive officers granted shares | executive

4

Restricted Stock and Restricted Stock Units, Subject to Performance Conditions | Senior Executives

Class of Stock [Line Items]

Award vesting period

4 years

Equity instruments other than options, grants in period (in shares)

528,000

Number of executive officers granted shares | executive

2

Award post-vesting holding period

2 years

Restricted Stock and Restricted Stock Units, Subject to Performance Conditions | Minimum | Executive Officer

Class of Stock [Line Items]

Award vesting period

34 months

Restricted Stock and Restricted Stock Units, Subject to Performance Conditions | Maximum | Executive Officer

Class of Stock [Line Items]

Award vesting period

60 months

Restricted Stock and Restricted Stock Units, Not Subject to Performance Conditions | Executive Officer

Class of Stock [Line Items]

Award vesting period

3 years

Equity instruments other than options, grants in period (in shares)

284,813

Equity instruments other than options, granted in period, fair value | $

$ 5,913,000

Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) | $ / shares

$ 20.76

Number of executive officers granted shares | executive

5

Restricted Stock

Class of Stock [Line Items]

Equity instruments other than options, grants in period (in shares)

731,282

Equity instruments other than options, granted in period, fair value | $

$ 7,824,000

Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) | $ / shares

$ 14.82

Shares paid for tax withholding for share based compensation (in shares)

133,027

Shares paid for tax withholding for share based compensation, value | $

$ 2,774,000

Shares paid for tax withholding for share based compensation, value per share (in dollars per share) | $ / shares

$ 20.85

Restricted Stock | Non-employees, directors

Class of Stock [Line Items]

Award vesting period

3 years

Equity instruments other than options, grants in period (in shares)

44,424

Equity instruments other than options, granted in period, fair value | $

$ 1,080,000

Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) | $ / shares

$ 24.31

Restricted Stock | Executive Officer

Class of Stock [Line Items]

Number of executive officers granted shares | executive

6

Restricted Stock | Minimum

Class of Stock [Line Items]

Award vesting period

3 years

Number of shares vested in period

384,000

Restricted Stock | Maximum

Class of Stock [Line Items]

Award vesting period

4 years

Number of shares vested in period

528,000

Restricted Stock Units

Class of Stock [Line Items]

Shares paid for tax withholding for share based compensation (in shares)

6,507

Shares paid for tax withholding for share based compensation, value | $

$ 135,000

Shares paid for tax withholding for share based compensation, value per share (in dollars per share) | $ / shares

$ 20.75

Incentive Plan

Class of Stock [Line Items]

Number of shares authorized for award (in shares)

5,050,000

5,050,000

1,000,000

Number of additional shares authorized for award (in shares)

1,700,000

Share-based compensation arrangement by share-based payment award, expiration period

10 years

Maximum percentage of exercise price at grant date fair value

100.00%

Number of shares available for grant (in shares)

437,276

437,276

Incentive Plan | Incentive Stock Options

Class of Stock [Line Items]

Number of shares authorized for award (in shares)

600,000

600,000

Quarterly Dividend

Class of Stock [Line Items]

Common stock, dividends, per share, cash paid (in dollars per share) | $ / shares

$ 0.08

$ 0.08

$ 0.075

$ 0.075

$ 0.075

$ 0.075

$ 0.16

$ 0.30

Quarterly Dividend | Subsequent Event

Class of Stock [Line Items]

Dividends declared, amount per share (in dollars per share) | $ / shares

$ 0.08

SHAREHOLDERS' EQUITY SHAREHOL_2

SHAREHOLDERS' EQUITY SHAREHOLDERS EQUITY - Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Stockholders' Equity Note [Abstract]
Restricted stock	$ 4,349	$ 3,662	$ 7,777	$ 6,812
ESOP	944	658	1,724	1,490
Total stock based compensation	$ 5,293	$ 4,320	$ 9,501	$ 8,302

EARNINGS PER SHARE (EPS) (Detai

EARNINGS PER SHARE (EPS) (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Common shares outstanding (in shares)	56,684	47,431	56,684	47,431
Unallocated ESOP shares (in shares)	(1,961)	(2,159)	(1,961)	(2,159)
Non-vested restricted stock (in shares)	(3,822)	(3,562)	(3,822)	(3,562)
Impact of weighted average shares (in shares)	(63)	(145)	(184)	(341)
Weighted average shares outstanding - basic (in shares)	50,838	41,565	50,717	41,369
Incremental shares from stock based compensation (in shares)	2,426	2,169	2,494	2,457
Weighted average shares outstanding - diluted (in shares)	53,264	43,734	53,211	43,826

BUSINESS SEGMENTS - Revenues (D

BUSINESS SEGMENTS - Revenues (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2021USD ($)segment	Mar. 31, 2020USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenue	$ 634,832	$ 566,350	$ 1,244,123	$ 1,114,788
Consumer and Professional Products
Segment Reporting Information [Line Items]
Revenue	331,871	274,912	622,913	515,988
Home and Building Products
Segment Reporting Information [Line Items]
Revenue	242,811	209,829	493,292	451,210
Defense Electronics
Segment Reporting Information [Line Items]
Revenue	$ 60,150	$ 81,609	$ 127,918	$ 147,590

BUSINESS SEGMENTS - Disaggregat

BUSINESS SEGMENTS - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 634,832	$ 566,350	$ 1,244,123	$ 1,114,788
United States
Disaggregation of Revenue [Line Items]
Revenue	470,489	445,543	937,840	878,794
Europe
Disaggregation of Revenue [Line Items]
Revenue	44,797	34,622	64,858	47,235
Canada
Disaggregation of Revenue [Line Items]
Revenue	33,500	29,591	68,932	61,199
Australia
Disaggregation of Revenue [Line Items]
Revenue	63,813	39,221	133,672	94,055
All other countries
Disaggregation of Revenue [Line Items]
Revenue	22,233	17,373	38,821	33,505
Consumer and Professional Products
Disaggregation of Revenue [Line Items]
Revenue	331,871	274,912	622,913	515,988
Consumer and Professional Products | United States
Disaggregation of Revenue [Line Items]
Revenue	205,368	191,412	388,810	351,570
Consumer and Professional Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	38,965	24,737	52,121	31,342
Consumer and Professional Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	21,778	17,515	43,893	35,296
Consumer and Professional Products | Australia
Disaggregation of Revenue [Line Items]
Revenue	63,691	39,032	133,231	93,260
Consumer and Professional Products | All other countries
Disaggregation of Revenue [Line Items]
Revenue	2,069	2,216	4,858	4,520
Consumer and Professional Products | Residential repair and remodel
Disaggregation of Revenue [Line Items]
Revenue	50,560	40,505	96,160	75,595
Consumer and Professional Products | Retail
Disaggregation of Revenue [Line Items]
Revenue	153,746	144,904	292,994	264,524
Consumer and Professional Products | Residential new construction
Disaggregation of Revenue [Line Items]
Revenue	14,540	14,884	28,055	29,857
Consumer and Professional Products | Industrial
Disaggregation of Revenue [Line Items]
Revenue	9,958	10,535	19,489	21,158
Consumer and Professional Products | International excluding North America
Disaggregation of Revenue [Line Items]
Revenue	103,067	64,084	186,215	124,854
Home and Building Products
Disaggregation of Revenue [Line Items]
Revenue	242,811	209,829	493,292	451,210
Home and Building Products | United States
Disaggregation of Revenue [Line Items]
Revenue	230,955	199,060	467,486	426,010
Home and Building Products | Europe
Disaggregation of Revenue [Line Items]
Revenue	41	5	41	28
Home and Building Products | Canada
Disaggregation of Revenue [Line Items]
Revenue	9,797	7,867	21,285	19,120
Home and Building Products | Australia
Disaggregation of Revenue [Line Items]
Revenue	0	0	0	0
Home and Building Products | All other countries
Disaggregation of Revenue [Line Items]
Revenue	2,018	2,897	4,480	6,052
Home and Building Products | Residential repair and remodel
Disaggregation of Revenue [Line Items]
Revenue	120,827	100,808	246,942	222,805
Home and Building Products | Residential new construction
Disaggregation of Revenue [Line Items]
Revenue	27,233	22,721	55,660	50,218
Home and Building Products | Commercial construction
Disaggregation of Revenue [Line Items]
Revenue	94,751	86,300	190,690	178,187
Defense Electronics
Disaggregation of Revenue [Line Items]
Revenue	60,150	81,609	127,918	147,590
Defense Electronics | United States
Disaggregation of Revenue [Line Items]
Revenue	34,166	55,071	81,544	101,214
Defense Electronics | Europe
Disaggregation of Revenue [Line Items]
Revenue	5,791	9,880	12,696	15,865
Defense Electronics | Canada
Disaggregation of Revenue [Line Items]
Revenue	1,925	4,209	3,754	6,783
Defense Electronics | Australia
Disaggregation of Revenue [Line Items]
Revenue	122	189	441	795
Defense Electronics | All other countries
Disaggregation of Revenue [Line Items]
Revenue	18,146	12,260	29,483	22,933
Defense Electronics | U.S. Government
Disaggregation of Revenue [Line Items]
Revenue	35,045	53,623	82,369	96,324
Defense Electronics | International
Disaggregation of Revenue [Line Items]
Revenue	21,497	25,021	38,392	43,554
Defense Electronics | Commercial
Disaggregation of Revenue [Line Items]
Revenue	$ 3,608	$ 2,965	$ 7,157	$ 7,712

BUSINESS SEGMENTS - Segment EBI

BUSINESS SEGMENTS - Segment EBITDA (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 67,781	$ 47,963	$ 142,421	$ 103,123
Depreciation and amortization	(15,883)	(15,719)	(31,149)	(31,544)
Loss from debt extinguishment, net	0	(6,690)	0	(6,690)
Income before taxes	27,860	2,929	67,029	19,880
Operating Segments
Segment Reporting Information [Line Items]
Adjusted EBITDA	79,703	59,910	166,370	127,012
Depreciation and amortization	(15,733)	(15,566)	(30,949)	(31,241)
Operating Segments | Consumer and Professional Products
Segment Reporting Information [Line Items]
Adjusted EBITDA	37,423	25,027	70,136	46,953
Depreciation and amortization	(8,620)	(8,222)	(16,819)	(16,453)
Operating Segments | Home and Building Products
Segment Reporting Information [Line Items]
Adjusted EBITDA	40,060	30,635	88,429	71,336
Depreciation and amortization	(4,379)	(4,668)	(8,720)	(9,468)
Operating Segments | Defense Electronics
Segment Reporting Information [Line Items]
Adjusted EBITDA	2,220	4,248	7,805	8,723
Depreciation and amortization	(2,734)	(2,676)	(5,410)	(5,320)
Segment Reconciling Items
Segment Reporting Information [Line Items]
Unallocated Expenses	(11,922)	(11,947)	(23,949)	(23,889)
Net interest expense	(15,527)	(16,561)	(31,172)	(32,511)
Depreciation and amortization	(15,883)	(15,719)	(31,149)	(31,544)
Loss from debt extinguishment, net	0	(6,690)	0	(6,690)
Restructuring charges	(7,562)	(3,104)	(18,362)	(9,538)
Acquisition costs	0	2,960	0	2,960
Gain (adjustment) on sale of SEG business	$ (949)	$ 0	$ 5,291	$ 0

BUSINESS SEGMENTS - Depreciatio

BUSINESS SEGMENTS - Depreciation, Amortization and Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
DEPRECIATION and AMORTIZATION	$ 15,883	$ 15,719	$ 31,149	$ 31,544
CAPITAL EXPENDITURES	12,060	9,347	23,986	22,519
Operating Segments
Segment Reporting Information [Line Items]
DEPRECIATION and AMORTIZATION	15,733	15,566	30,949	31,241
CAPITAL EXPENDITURES	12,058	9,277	23,984	22,237
Corporate
Segment Reporting Information [Line Items]
DEPRECIATION and AMORTIZATION	150	153	200	303
CAPITAL EXPENDITURES	2	70	2	282
Consumer and Professional Products | Operating Segments
Segment Reporting Information [Line Items]
DEPRECIATION and AMORTIZATION	8,620	8,222	16,819	16,453
CAPITAL EXPENDITURES	6,813	3,800	13,720	7,532
Home and Building Products | Operating Segments
Segment Reporting Information [Line Items]
DEPRECIATION and AMORTIZATION	4,379	4,668	8,720	9,468
CAPITAL EXPENDITURES	1,998	3,556	4,113	11,495
Defense Electronics | Operating Segments
Segment Reporting Information [Line Items]
DEPRECIATION and AMORTIZATION	2,734	2,676	5,410	5,320
CAPITAL EXPENDITURES	$ 3,247	$ 1,921	$ 6,151	$ 3,210

BUSINESS SEGMENTS - Summary of

BUSINESS SEGMENTS - Summary of Segment Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Continuing assets	$ 2,517,460	$ 2,439,942
Assets of discontinued operations	6,820	8,497
Total Assets	2,524,280	2,448,439
Operating Segments
Segment Reporting Information [Line Items]
Continuing assets	2,300,889	2,191,040
Operating Segments | Consumer and Professional Products
Segment Reporting Information [Line Items]
Continuing assets	1,408,545	1,255,127
Operating Segments | Home and Building Products
Segment Reporting Information [Line Items]
Continuing assets	604,325	606,785
Operating Segments | Defense Electronics
Segment Reporting Information [Line Items]
Continuing assets	288,019	329,128
Corporate
Segment Reporting Information [Line Items]
Continuing assets	$ 216,571	$ 248,902

EMPLOYEE BENEFIT PLANS (Details

EMPLOYEE BENEFIT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Retirement Benefits [Abstract]
Interest cost	$ 745	$ 1,151	$ 1,489	$ 2,302
Expected return on plan assets	(2,545)	(2,586)	(5,089)	(5,172)
Amortization:
Prior service cost	0	4	0	8
Recognized actuarial loss	1,573	1,042	3,146	2,084
Net periodic expense (income)	$ (227)	$ (389)	$ (454)	$ (778)

DISCONTINUED OPERATIONS - Balan

DISCONTINUED OPERATIONS - Balance Sheets Information (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Assets of discontinued operations:
Prepaid and other current assets	$ 1,525	$ 2,091
Other long-term assets	5,295	6,406
Total assets of discontinued operations	6,820	8,497
Liabilities of discontinued operations:
Accrued liabilities, current	4,600	3,797
Other long-term liabilities	6,415	7,014
Total liabilities of discontinued operations	$ 11,015	$ 10,811

RESTRUCTURING CHARGES - Narrati

RESTRUCTURING CHARGES - Narrative (Details) $ in Thousands	Nov. 12, 2020USD ($)	Sep. 30, 2020USD ($)position	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Mar. 31, 2021USD ($)position	Mar. 31, 2020USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 7,562			$ 3,104	$ 18,362	$ 9,538
Non-cash charges			2,497	$ 5,794
Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring charges			7,502			3,104	10,581	9,538
Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring costs							7,891	4,846
Non-cash charges							$ 2,690	4,692
Impairment charge, operating lease								1,968
Impairment charge, leasehold improvements								671
Inventory write down								304
Impairment charge, manufacturing assets								1,749
Reduction of headcount | position							65
Voluntary Employee Retirement Plan | Defense Electronics
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost		$ 4,300			$ 4,300
Restructuring charges					$ 2,120		$ 2,180
Reduction of headcount | position		90
Exit of Older Weather Radar Product Lines
Restructuring Cost and Reserve [Line Items]
Business exit costs				5,601
Minimum | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Annual cash savings	$ 30,000
Reduction in inventory	30,000
Maximum | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Annual cash savings	35,000
Reduction in inventory	35,000
One-time charges | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	65,000
Capital investments | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	65,000
Cash charges | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	46,000
Personnel related costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			782			1,658	3,264	3,792
Non-cash charges			0	0
Personnel related costs | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	26,000
Restructuring costs							1,084	3,792
Facilities, exit costs and other
Restructuring Cost and Reserve [Line Items]
Restructuring charges			4,283			$ 914	6,807	1,054
Non-cash charges			$ 0	$ 0
Facilities, exit costs and other | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	20,000
Restructuring costs							$ 6,807	$ 1,054
Asset write-downs | Next-generation Business Platform | Consumer and Professional Products
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, expected cost	$ 19,000

RESTRUCTURING CHARGES - Summary

RESTRUCTURING CHARGES - Summary of the Restructuring and Other Related Charges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 7,562	$ 3,104	$ 18,362	$ 9,538
Personnel related costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	782	1,658	3,264	3,792
Facilities, exit costs and other
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,283	914	6,807	1,054
Non-cash facility and other
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,497	532	8,291	4,692
Cost of goods and services
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,337	1,353	9,762	4,076
Selling, general and administrative expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4,225	$ 1,751	$ 8,600	$ 5,462

RESTRUCTURING CHARGES - Summa_2

RESTRUCTURING CHARGES - Summary of Accrued Liability for the Restructuring and Related Charges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2021
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	$ 3,839	$ 2,965	$ 2,965
Restructuring charges	7,562	10,800
Cash payment	(8,113)	(4,132)
Non-cash charges	(2,497)	(5,794)
Accrued liability ending balance	791	3,839	791
Personnel related costs
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	3,585	2,701	2,701
Restructuring charges	782	2,482
Cash payment	(3,840)	(1,598)
Non-cash charges	0	0
Accrued liability ending balance	527	3,585	527
Facilities, exit costs and other
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	254	264	264
Restructuring charges	4,283	2,524
Cash payment	(4,273)	(2,534)
Non-cash charges	0	0
Accrued liability ending balance	264	254	264
Facility and Other Costs
Restructuring Reserve [Roll Forward]
Accrued liability beginning balance	0	0	0
Restructuring charges	2,497	5,794
Cash payment	0	0
Non-cash charges	(2,497)	(5,794)
Accrued liability ending balance	$ 0	$ 0	$ 0

OTHER INCOME (EXPENSE) (Details

OTHER INCOME (EXPENSE) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Other Income and Expenses [Abstract]
Other income (expense)	$ 847	$ 615	$ 806	$ 1,393
Foreign currency transaction gain (loss), before tax	320	745	(379)	369
Net periodic benefit income	227	389	454	778
Investment income, net	$ 55	$ (230)	386	$ (149)
Technology recognition award			$ 700

WARRANTY LIABILITY - Narrative

WARRANTY LIABILITY - Narrative (Details)	6 Months Ended
	Mar. 31, 2021
DE | Minimum
Product Warranty Liability [Line Items]
Product warranty period	1 year
DE | Maximum
Product Warranty Liability [Line Items]
Product warranty period	2 years
HBP | Minimum
Product Warranty Liability [Line Items]
Product warranty period	1 year
HBP | Maximum
Product Warranty Liability [Line Items]
Product warranty period	10 years
CPP
Product Warranty Liability [Line Items]
Product warranty period	90 days

WARRANTY LIABILITY - Changes in

WARRANTY LIABILITY - Changes in Warrant Liability (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Balance, beginning of period	$ 10,834	$ 7,344	$ 10,843	$ 7,894
Warranties issued and changes in estimated pre-existing warranties	6,477	4,862	11,216	8,227
Actual warranty costs incurred	(4,633)	(4,417)	(9,381)	(8,332)
Balance, end of period	$ 12,678	$ 7,789	$ 12,678	$ 7,789

OTHER COMPREHENSIVE INCOME (L_3

OTHER COMPREHENSIVE INCOME (LOSS) - Summary of OCI (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	$ 5,883		$ (14,241)		$ 19,173	$ (7,354)
Total other comprehensive income (loss), tax	(1,108)		(593)		(1,257)	(639)
Total other comprehensive income (loss), net of taxes	4,775	$ 13,141	(14,834)	$ 6,841	17,916	(7,993)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	1,739		(16,471)		13,862	(10,001)
Total other comprehensive income (loss), tax	0		0		0	0
Total other comprehensive income (loss), net of taxes	1,739		(16,471)		13,862	(10,001)
Pension and other defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	1,585		847		3,735	1,694
Total other comprehensive income (loss), tax	(340)		(178)		(784)	(353)
Total other comprehensive income (loss), net of taxes	1,245		669		2,951	1,341
Cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total other comprehensive income (loss), pre-tax	2,559		1,383		1,576	953
Total other comprehensive income (loss), tax	(768)		(415)		(473)	(286)
Total other comprehensive income (loss), net of taxes	$ 1,791		$ 968		$ 1,103	$ 667

OTHER COMPREHENSIVE INCOME (L_4

OTHER COMPREHENSIVE INCOME (LOSS) - AOCI (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	$ 764,431	$ 740,047	$ 700,151	$ 476,454	$ 494,693	$ 477,763
Foreign currency translation adjustments
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	(11,821)		(25,683)
Pension and other defined benefit plans
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	(43,647)		(46,598)
Cash flow hedges
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	1,292		189
Accumulated other comprehensive income (loss), attributable to parent
Class of Stock [Line Items]
Accumulated other comprehensive income (loss)	$ (54,176)	$ (58,951)	$ (72,092)	$ (73,909)	$ (59,075)	$ (65,916)

OTHER COMPREHENSIVE INCOME (L_5

OTHER COMPREHENSIVE INCOME (LOSS) - Amounts Reclassified from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss)	$ 27,860		$ 2,929		$ 67,029	$ 19,880
Tax benefit (expense)	(10,748)		(2,034)		(20,417)	(8,373)
Net income	17,112	$ 29,500	895	$ 10,612	46,612	11,507
Pension and other defined benefit plans | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss)	(1,573)		(1,046)		(3,146)	(2,092)
Cash flow hedges | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss)	(1,741)		1,050		(2,399)	994
Accumulated other comprehensive income (loss), attributable to parent | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Total gain (loss)	(3,314)		4		(5,545)	(1,098)
Tax benefit (expense)	696		(1)		1,165	231
Net income	$ (2,618)		$ 3		$ (4,380)	$ (867)

LEASES - Narrative (Details)

LEASES - Narrative (Details) $ in Thousands	6 Months Ended
	Mar. 31, 2021USD ($)renewalOption	Sep. 30, 2020USD ($)
Lessee, Lease, Description [Line Items]
Long-term debt | $	$ 1,058,772	$ 1,046,964
Finance Lease Obligation
Lessee, Lease, Description [Line Items]
Long-term debt | $	$ 15,907	$ 17,188
Troy, Ohio
Lessee, Lease, Description [Line Items]
Percentage bearing fixed interest, percentage rate	5.00%
Troy, Ohio | Finance Lease Obligation
Lessee, Lease, Description [Line Items]
Percentage bearing fixed interest, percentage rate	5.00%
Ocala, Florida
Lessee, Lease, Description [Line Items]
Percentage bearing fixed interest, percentage rate	5.60%
Number of option to extend | renewalOption	2
Lease renewal term	5 years
Ocala, Florida | Finance Lease Obligation
Lessee, Lease, Description [Line Items]
Percentage bearing fixed interest, percentage rate	5.60%
Number of option to extend | renewalOption	2

LEASES - Schedule of Lease Cost

LEASES - Schedule of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Lease Cost
Fixed	$ 9,970	$ 9,187	$ 20,010	$ 18,739
Variable	2,087	1,823	4,134	3,576
Short-term	1,053	1,393	2,167	2,823
Total	$ 13,110	$ 12,403	$ 26,311	$ 25,138

LEASES - Supplemental Cash Flow

LEASES - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 22,099	$ 21,582
Financing cash flows from finance leases	1,865	1,940
Total	$ 23,964	$ 23,522

LEASES - Summary of Supplementa

LEASES - Summary of Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Operating Leases:
Operating right-of-use assets	$ 154,929	$ 161,627
Lease Liabilities:
Current portion of operating lease liabilities	30,685	31,848
Long-term operating lease liabilities	128,714	136,054
Total operating lease liabilities	159,399	167,902
Finance Leases:
Property, plant and equipment, net	$ 18,068	$ 18,774
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	PROPERTY, PLANT AND EQUIPMENT, net	PROPERTY, PLANT AND EQUIPMENT, net
Lease Liabilities:
Lease liabilities, notes payable and current portion of long-term debt	$ 3,110	$ 3,352
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Notes payable and current portion of long-term debt	Notes payable and current portion of long-term debt
Lease liabilities, long-term debt, net	$ 14,950	$ 15,339
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtNoncurrent	us-gaap:LongTermDebtNoncurrent
Total financing lease liabilities	$ 18,060	$ 18,691
Accumulated depreciation	$ 4,296	$ 2,383

LEASES - Summary of Future Matu

LEASES - Summary of Future Maturities of Lease Payments for Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Operating Leases
2020	$ 19,128
2021	34,484
2022	26,884
2023	20,180
2024	18,214
2025	12,376
Thereafter	63,859
Total lease payments	195,125
Less: Imputed Interest	(35,726)
Present value of lease liabilities	159,399	$ 167,902
Finance Leases
2021	2,381
2021	3,087
2022	2,749
2023	2,195
2024	2,077
2025	2,075
Thereafter	7,777
Total lease payments	22,341
Less: Imputed Interest	(4,281)
Present value of lease liabilities	$ 18,060	$ 18,691

LEASES - Weighted Average Lease

LEASES - Weighted Average Lease Terms and Discount Rates (Details)	Mar. 31, 2021
Weighted-average remaining lease term (years)
Operating leases	8 years 1 month 6 days
Finance Leases	8 years 2 months 12 days
Weighted-average discount rate
Operating Leases	4.45%
Finance Leases	5.50%

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Apr. 30, 2009USD ($)
Commitments and Contingencies Disclosure [Abstract]
Net capital cost value in proposed remedial action plan	$ 10,000