BUSINESS SEGMENTS - Income Before Taxes From Continuing Operations (Details) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Segment operating profit:		$ 36,494	$ 23,570	$ 91,507	$ 54,611
Net interest expense		(17,087)	(15,796)	(50,723)	(48,482)
Unallocated amounts		(12,175)	(12,016)	(34,920)	(32,993)
Acquisition costs		0
Secondary equity offering costs		0	(1,205)	0	(1,205)
Cost of life insurance benefit	$ (13,715)
Income before taxes from continuing operations		20,386	9,002	44,035	10,117
Continuing Operations [Member]
Segment Reporting Information [Line Items]
Special dividend ESOP charges		0	(3,220)	0	(3,220)
Postretirement Life Insurance [Member] \| Continuing Operations [Member]
Segment Reporting Information [Line Items]
Segment operating profit from continuing operations		49,648	44,837	129,678	103,848
Net interest expense		(17,087)	(15,796)	(50,723)	(48,482)
Unallocated amounts		(12,175)	(12,016)	(34,920)	(32,993)
Acquisition costs		0	(3,598)	0	(5,217)
Cost of life insurance benefit		0	0	0	(2,614)
Income before taxes from continuing operations		20,386	9,002	44,035	10,117
Postretirement Life Insurance [Member] \| Continuing Operations [Member] \| Home And Building Products [Member]
Segment Reporting Information [Line Items]
Segment operating profit:		45,037	38,753	120,603	94,982
Postretirement Life Insurance [Member] \| Continuing Operations [Member] \| Telephonics [Member]
Segment Reporting Information [Line Items]
Segment operating profit:		$ 4,611	$ 6,084	$ 9,075	$ 8,866

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Gross Profit from Continuing Operations

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Amount of unallocated expense included in noninterest expense for the reportable segment during the period.

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Special Dividend ESOP Charges

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Amount of gain (loss) recognized in net periodic benefit (cost) credit from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk related to obligation and assets used to effect settlement.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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The net amount of operating interest income (expense).

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The net result for the period of deducting operating expenses from operating revenues.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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