CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 498,511	$ 568,851	$ 473,840
Unrealized gains and losses on available for sale debt securities
Net gains (losses) arising during the period	12,950	(136,981)	(23,613)
Less reclassification adjustment for net gains included in net income	(634)	(23)	(491)
Total	12,316	(137,004)	(24,104)
Unrealized gains and losses on derivatives (cash flow hedges)
Net (losses) gains on derivatives arising during the period	(757)	3,362	127
Less reclassification adjustment for net losses included in net income	638	203	2,447
Total	(119)	3,565	2,574
Defined benefit pension and postretirement benefit plans
Net gains (losses) arising during the period	5,436	(13,175)	10,306
Amortization of prior service credit	(90)	(100)	(96)
Amortization of actuarial net loss	3	644	1,106
Total	5,349	(12,631)	11,316
Other comprehensive income (loss), net	17,546	(146,070)	(10,214)
Total comprehensive income	$ 516,057	$ 422,781	$ 463,626