Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock Outstanding	Common Stock	Value of Shares Held in Rabbi Trust at Cost	Deferred Compensation and Other Retirement Benefit Obligations	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding		32,965,692
Net income	$ 79,283						$ 79,283
Other comprehensive income	(11,128)							$ (11,128)
Cash dividends declared per common share (in dollars per share)							$ 0.96
Common dividend declared	(31,711)						$ (31,711)
Proceeds from exercise of stock options, net of cash paid		4,744
Proceeds from exercise of stock options, net of cash paid			$ 0
Stock Repurchased During Period, Value, as a result of Stock Options Exercised	(57)					$ (57)
Stock based compensation	2,760					2,760
Restricted stock awards issued, net of awards surrendered		54,558
Restricted stock awards issued, net of awards surrendered	(1,243)		1			(1,244)
Shares issued under direct stock purchase plan		12,865
Shares issued under direct stock purchase plan	1,033		0			1,033
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				$ (50)	$ 50
Increase (Decrease) in Deferred Compensation	0
Period End Balance at Jun. 30, 2021	1,741,622		329	(3,116)	3,116	948,130	763,596	29,567
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding		33,024,882
Net income	37,572						$ 37,572
Other comprehensive income	2,410							2,410
Cash dividends declared per common share (in dollars per share)							$ 0.48
Common dividend declared	(15,859)						$ (15,859)
Stock based compensation	1,610					1,610
Restricted stock awards issued, net of awards surrendered		6,452
Restricted stock awards issued, net of awards surrendered	(23)					(23)
Shares issued under direct stock purchase plan		6,525
Shares issued under direct stock purchase plan	541					541
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				(36)	36
Increase (Decrease) in Deferred Compensation	0
Period End Balance at Jun. 30, 2021	$ 1,741,622		329	(3,116)	3,116	948,130	763,596	29,567
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding		33,037,859
Common Stock, Shares, Outstanding	47,349,778	47,349,778
Net income	$ 114,873						$ 114,873
Other comprehensive income	(111,647)							(111,647)
Cash dividends declared per common share (in dollars per share)							$ 1.02
Common dividend declared	(47,732)						$ (47,732)
Stock based compensation	2,466					2,466
Restricted stock awards issued, net of awards surrendered		49,800
Restricted stock awards issued, net of awards surrendered	(1,085)					(1,085)
Shares issued under direct stock purchase plan		14,176
Shares issued under direct stock purchase plan	1,159					1,159
Stock Repurchased During Period, Shares		(1,343,993)
Stock Repurchased During Period, Value	(105,298)		(13)			(105,285)
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				(50)	50
Increase (Decrease) in Deferred Compensation	0
Period End Balance at Jun. 30, 2022	2,871,185		459	(3,196)	3,196	2,146,333	833,857	(109,464)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding		47,377,125
Net income	61,776						$ 61,776
Other comprehensive income	(31,262)							(31,262)
Cash dividends declared per common share (in dollars per share)							$ 0.51
Common dividend declared	(23,570)						$ (23,570)
Stock based compensation	1,632					1,632
Restricted stock awards issued, net of awards surrendered		5,231
Restricted stock awards issued, net of awards surrendered	(22)					(22)
Shares issued under direct stock purchase plan		7,574
Shares issued under direct stock purchase plan	588					588
Stock Repurchased During Period, Shares		(1,320,169)
Stock Repurchased During Period, Value	(103,396)		(13)			(103,383)
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				(17)	17
Increase (Decrease) in Deferred Compensation	0
Period End Balance at Jun. 30, 2022	$ 2,871,185		$ 459	$ (3,196)	$ 3,196	$ 2,146,333	$ 833,857	$ (109,464)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding	46,069,761	46,069,761