Shareholders' Equity Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (599,100)	$ (836,955)	$ 72,371
Net change in unrealized gain (loss)	33,461	218,293	(1,227,414)
Transfer of net unrealized loss from AFS to investment securities			0
Reclassification adjustments included in earnings: [Abstract]
Interest revenue, Investment securities	46,020	60,394	42,514
Operating expense, Personnel			(3,483)
Loss on available for sale securities, net	45,828	30,636	971
Other comprehensive income (loss), before income taxes	125,309	309,323	(1,187,412)
Federal and state income taxes	29,249	71,468	(278,086)
Other comprehensive income (loss), net of income taxes	96,060	237,855	(909,326)
Ending balance	(503,040)	(599,100)	(836,955)
Unrealized Gain (Loss) on Available for Sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(473,212)	(664,618)	69,775
Net change in unrealized gain (loss)	33,461	218,293	(1,227,414)
Transfer of net unrealized loss from AFS to investment securities			267,509
Reclassification adjustments included in earnings: [Abstract]
Interest revenue, Investment securities	0	0	0
Operating expense, Personnel			0
Loss on available for sale securities, net	45,828	30,636	971
Other comprehensive income (loss), before income taxes	79,289	248,929	(958,934)
Federal and state income taxes	18,425	57,523	(224,541)
Other comprehensive income (loss), net of income taxes	60,864	191,406	(734,393)
Ending balance	(412,348)	(473,212)	(664,618)
Accumulated Unrealized Gain/Loss on Investment Securities Transferred from AFS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(125,888)	(172,337)	0
Net change in unrealized gain (loss)	0	0	0
Transfer of net unrealized loss from AFS to investment securities			(267,509)
Reclassification adjustments included in earnings: [Abstract]
Interest revenue, Investment securities	46,020	60,394	42,514
Operating expense, Personnel			0
Loss on available for sale securities, net	0	0	0
Other comprehensive income (loss), before income taxes	46,020	60,394	(224,995)
Federal and state income taxes	10,824	13,945	(52,658)
Other comprehensive income (loss), net of income taxes	35,196	46,449	(172,337)
Ending balance	(90,692)	(125,888)	(172,337)
Unrealized Gain (Loss) on Employee Benefit Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	0	2,596
Net change in unrealized gain (loss)	0	0	0
Transfer of net unrealized loss from AFS to investment securities			0
Reclassification adjustments included in earnings: [Abstract]
Interest revenue, Investment securities	0	0	0
Operating expense, Personnel			(3,483)
Loss on available for sale securities, net	0	0	0
Other comprehensive income (loss), before income taxes	0	0	(3,483)
Federal and state income taxes	0	0	(887)
Other comprehensive income (loss), net of income taxes	0	0	(2,596)
Ending balance	$ 0	$ 0	$ 0