Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Apr. 30, 2024	Mar. 31, 2024	Mar. 31, 2023
Dividends declared (in dollars per share)		$ 0.55	$ 0.54
Schedule of Accumulated Other Income (Loss) [Abstract]
Balance, Beginning of Period		$ (599,100)	$ (836,955)
Net change in unrealized gain (loss)		(71,806)	124,045
Interest revenue, Investment securities		12,183	16,051
Loss on available for sale securities, net		45,171	0
Other comprehensive income, before income taxes		(14,452)	140,096
Federal and state income taxes		(3,424)	31,695
Other comprehensive income, net of income taxes		(11,028)	108,401
Balance, End of Period		(610,128)	(728,554)
Accumulated Net Unrealized Gain (Loss) on Available for Sale Securities [Member]
Schedule of Accumulated Other Income (Loss) [Abstract]
Balance, Beginning of Period		(473,212)	(664,618)
Net change in unrealized gain (loss)		(71,806)	124,045
Interest revenue, Investment securities		0	0
Loss on available for sale securities, net		45,171
Other comprehensive income, before income taxes		(26,635)	124,045
Federal and state income taxes		(6,289)	28,179
Other comprehensive income, net of income taxes		(20,346)	95,866
Balance, End of Period		(493,558)	(568,752)
AOCI, Accumulated Gain (Loss), Debt Securities, Investment Securities Transferred from Available-for-sale, Parent
Schedule of Accumulated Other Income (Loss) [Abstract]
Balance, Beginning of Period		(125,888)	(172,337)
Net change in unrealized gain (loss)		0	0
Interest revenue, Investment securities		12,183	16,051
Loss on available for sale securities, net		0
Other comprehensive income, before income taxes		12,183	16,051
Federal and state income taxes		2,865	3,516
Other comprehensive income, net of income taxes		9,318	12,535
Balance, End of Period		$ (116,570)	$ (159,802)
Subsequent Event [Member]
Dividends Payable, Date Declared	Apr. 30, 2024
Dividends declared (in dollars per share)	$ 0.55
Dividends Payable, Date to be Paid	May 30, 2024
Dividends Payable, Date of Record	May 15, 2024