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	$ 41,711						$ 41,711
Other comprehensive income	(13,538)							$ (13,538)
Cash dividends declared per common share (in dollars per share)							$ 0.48
Common dividend declared	(15,852)						$ (15,852)
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	1,150					1,150
Restricted stock awards issued, net of awards surrendered		48,106
Restricted stock awards issued, net of awards surrendered	(1,220)		1			(1,221)
Shares issued under direct stock purchase plan		6,340
Shares issued under direct stock purchase plan	492		0			492
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				$ (14)	$ 14
Increase (Decrease) in Deferred Compensation	0
Period End Balance at Mar. 31, 2021	$ 1,715,371		329	(3,080)	3,080	946,002	741,883	27,157
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding		33,024,882
Common Stock, Shares, Outstanding	47,349,778	47,349,778
Net income	$ 53,097						$ 53,097
Other comprehensive income	(80,385)							(80,385)
Cash dividends declared per common share (in dollars per share)							$ 0.51
Common dividend declared	(24,162)						$ (24,162)
Stock based compensation	834					834
Restricted stock awards issued, net of awards surrendered		44,569
Restricted stock awards issued, net of awards surrendered	(1,063)					(1,063)
Shares issued under direct stock purchase plan		6,602
Shares issued under direct stock purchase plan	571					571
Stock Repurchased During Period, Shares		(23,824)
Stock Repurchased During Period, Value	(1,902)					(1,902)
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				(33)	33
Increase (Decrease) in Deferred Compensation	0
Period End Balance at Mar. 31, 2022	$ 2,965,439		$ 472	$ (3,179)	$ 3,179	$ 2,247,518	$ 795,651	$ (78,202)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Outstanding	47,377,125	47,377,125