Securities, Amortized Cost and Fair Value and Allowance for Credit Loss on Securities Held-to-Maturity (Details) $ in Thousands		9 Months Ended
		Mar. 31, 2024 USD ($) Category		Dec. 31, 2023 USD ($)	Jun. 30, 2023 USD ($)
Held-to-maturity securities [Abstract]
Amortized cost	[1]	$ 700,869			$ 726,363
Unrealized gains		6,538			5,178
Unrealized losses		59,903			60,475
Fair value		647,504			671,066
Allowance		498	[2]	$ 485	0	[2]
Net carrying value		700,371			726,363
Accrued interest receivable		$ 5,300			3,900
Number of categories utilized under risk management approach of diversified investing | Category		3
U.S. Treasury Securities [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	$ 33,767			33,705
Unrealized gains		0			0
Unrealized losses		1,849			2,438
Fair value		31,918			31,267
Allowance	[2]	0			0
Net carrying value		33,767			33,705
State and Political Subdivisions [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	462,643			478,756
Unrealized gains		6,518			5,178
Unrealized losses		34,182			30,662
Fair value		434,979			453,272
Allowance	[2]	45			0
Net carrying value		462,598			478,756
Mortgage-backed Securities-Residential [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	33,947			37,186
Unrealized gains		0			0
Unrealized losses		3,319			3,625
Fair value		30,628			33,561
Allowance	[2]	0			0
Net carrying value		33,947			37,186
Mortgage-backed Securities-Multi-family [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	145,234			155,046
Unrealized gains		0			0
Unrealized losses		17,981			20,324
Fair value		127,253			134,722
Allowance	[2]	0			0
Net carrying value		145,234			155,046
Corporate Debt Securities [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	25,246			21,632
Unrealized gains		20			0
Unrealized losses		2,572			3,426
Fair value		22,694			18,206
Allowance	[2]	452			0
Net carrying value		24,794			21,632
Other Securities [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	32			38
Unrealized gains		0			0
Unrealized losses		0			0
Fair value		32			38
Allowance	[2]	1			0
Net carrying value		$ 31			$ 38

[1] Amortized cost excludes accrued interest receivable of $5.3 million and $3.9 million at March 31, 2024 and June 30, 2023, respectively, which is included in accrued interest receivable in the consolidated statements of financial condition.

[2] The Company adopted ASU 2016-13 (CECL) on July 1, 2023. For periods subsequent to adoption, an allowance is calculated under the CECL methodology. The periods prior to adoption did not have an allowance for credit losses under applicable GAAP for those periods.