Securities, Amortized Cost and Fair Value and Allowance for Credit Loss on Securities Held-to-Maturity (Details) $ in Thousands		6 Months Ended
		Dec. 31, 2023 USD ($) Category		Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)
Held-to-maturity securities [Abstract]
Amortized cost	[1]	$ 701,338			$ 726,363
Unrealized gains		6,248			5,178
Unrealized losses		56,373			60,475
Fair value		651,213			671,066
Allowance		485	[2]	$ 498	0	[2]
Net carrying value		700,853			726,363
Accrued interest receivable		$ 4,500			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]	$ 33,747			33,705
Unrealized gains		0			0
Unrealized losses		1,808			2,438
Fair value		31,939			31,267
Allowance	[2]	0			0
Net carrying value		33,747			33,705
State and Political Subdivisions [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	463,515			478,756
Unrealized gains		6,243			5,178
Unrealized losses		31,654			30,662
Fair value		438,104			453,272
Allowance	[2]	46			0
Net carrying value		463,469			478,756
Mortgage-backed Securities-Residential [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	34,912			37,186
Unrealized gains		0			0
Unrealized losses		2,969			3,625
Fair value		31,943			33,561
Allowance	[2]	0			0
Net carrying value		34,912			37,186
Mortgage-backed Securities-Multi-family [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	145,915			155,046
Unrealized gains		0			0
Unrealized losses		17,282			20,324
Fair value		128,633			134,722
Allowance	[2]	0			0
Net carrying value		145,915			155,046
Corporate Debt Securities [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	23,212			21,632
Unrealized gains		5			0
Unrealized losses		2,660			3,426
Fair value		20,557			18,206
Allowance	[2]	438			0
Net carrying value		22,774			21,632
Other Securities [Member]
Held-to-maturity securities [Abstract]
Amortized cost	[1]	37			38
Unrealized gains		0			0
Unrealized losses		0			0
Fair value		37			38
Allowance	[2]	1			0
Net carrying value		$ 36			$ 38

[1] Amortized cost excludes accrued interest receivable of $4.5 million and $3.9 million at December 31, 2023 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.