Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 34,029	$ 42,455	$ 129,366	$ 105,950
Net unrealized gains (losses) on available for sale securities and transferred securities:
Net unrealized holding gains (losses) arising during the period	(20,223)	(85,737)	(11,816)	(235,887)
Change in net unrealized holding loss on securities transferred to held to maturity	3,000	1,350	8,849	(23,588)
Reclassification adjustments for changes realized in net income:
Net change in prior service costs	21	21	62	62
Recognized net loss due to lump sum settlement	0	0	19	0
Change in net actuarial loss	52	221	162	686
Derivatives:
Change in the accumulated gain (loss) on effective cash flow hedge derivatives	(8,504)	(14,643)	(18,427)	(14,643)
Reclassification adjustment for (gain) loss realized in net income	3,470	(482)	8,666	(482)
Other comprehensive income (loss), net of tax	(22,184)	(99,270)	(12,485)	(273,852)
Comprehensive income (loss)	$ 11,845	$ (56,815)	$ 116,881	$ (167,902)