Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ 224,135	$ 223,009	$ 165,489
Net unrealized gains (losses) on available for sale securities and transferred securities:
Net unrealized holding gains (losses) arising during the period	46,043	(10,249)	38,133
Reclassification adjustment for net (gains) losses realized in net income	0	137,094	(29)
Change in net unrealized holding loss on securities transferred to held to maturity	10,324	10,940	11,668
Pension and other postretirement benefit plans:
Change in the actuarial loss of pension and other postretirement benefit plans	(495)	1,095	(518)
Reclassification adjustments for changes realized in net income:
Net change in prior service costs	11	83	83
Recognized net (gain) loss due to lump sum settlements	(59)	(10)	19
Change in net actuarial loss	95	186	133
Derivatives:
Change in the accumulated gain (loss) on effective cash flow hedge derivatives	6,974	(16,674)	(6,098)
Reclassification adjustment for (gain) loss realized in net income	7,141	13,599	12,289
Other comprehensive income (loss), net of tax	70,034	136,064	55,680
Comprehensive income (loss)	$ 294,169	$ 359,073	$ 221,169