Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Reconciliations of total equity
Beginning Balance	$ 1,166,065	$ 1,074,193	$ 1,074,193
Issuance of common stock under incentive compensation plan	1,514	114
Purchase of common stock		(9,935)
Stock-based and deferred compensation	(2,612)	2,017
Net income	16,142	44,809
Other comprehensive income	16,964	13,053
Cash dividends paid:
Common stock	(8,160)	(7,513)
Ending Balance	1,189,913	1,116,738
Common Stock [Member]
Reconciliations of total equity
Beginning Balance	26,841	26,761	26,761
Issuance of common stock under incentive compensation plan	26	2
Stock-based and deferred compensation	91	51
Cash dividends paid:
Ending Balance	26,958	26,814
Additional Paid-in Capital [Member]
Reconciliations of total equity
Beginning Balance	237,202	220,820	220,820
Issuance of common stock under incentive compensation plan	1,488	112
Stock-based and deferred compensation	895	3,568
Cash dividends paid:
Ending Balance	239,585	224,500
Common Treasury Stock [Member]
Reconciliations of total equity
Beginning Balance	(180,596)	(153,702)	(153,702)
Purchase of common stock		(9,935)
Stock-based and deferred compensation	(3,598)		(1,602)
Cash dividends paid:
Ending Balance	(184,194)	(165,239)
Accumulated Other Comprehensive Income (Loss) [Member]
Reconciliations of total equity
Beginning Balance	(167,512)	(153,236)	(153,236)
Other comprehensive income	16,964	13,053
Cash dividends paid:
Ending Balance	(150,548)	(140,183)
Retained Earnings [Member]
Reconciliations of total equity
Beginning Balance	1,250,130	1,133,550	$ 1,133,550
Net income	16,142	44,809
Cash dividends paid:
Common stock	(8,160)	(7,513)
Ending Balance	$ 1,258,112	$ 1,170,846