Accumulated Other Comprehensive Income (Loss) - AOCI Components Pre Post & Tax Effect (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Other Comprehensive Income (Loss), Before Tax:
Net Unrealized Gains (Losses) Arising During the Period	$ 32,918	$ (245,147)
Amortization of Unrealized Holding (Gains) Losses on HTM Securities	6,913	67
Net Unrealized Gains (Losses) on Investment Securities	39,831	(245,080)
Amortization of Net Actuarial Losses (Gains)	175	542
Amortization of Prior Service Credit	(61)	(62)
Defined Benefit Plans, Net	114	480
Other Comprehensive Income (Loss)	39,945	(244,600)
Other Comprehensive Income (Loss), Tax Effect:
Net Unrealized Gains (Losses) Arising During the Period	8,723	(64,974)
Amortization of Unrealized Holding (Gains) Losses on HTM Securities	1,832	18
Net Unrealized Gains (Losses) on Investment Securities	10,555	(64,956)
Amortization of Net Actuarial Losses (Gains)	47	143
Amortization of Prior Service Credit	(17)	(16)
Defined Benefit Plans, Net	30	127
Other Comprehensive Income (Loss)	10,585	(64,829)
Other Comprehensive Income (Loss), Net of Tax:
Net Unrealized Gains (Losses) Arising During the Period	24,195	(180,173)
Amortization of Unrealized Holding (Gains) Losses on HTM Securities	5,081	49
Net Unrealized Gains (Losses) on Investment Securities	29,276	(180,124)
Amortization of Net Actuarial Losses (Gains)	128	399
Amortization of Prior Service Credit	(44)	(46)
Defined Benefit Plans, Net	84	353
Total Other Comprehensive Income (Loss)	$ 29,360	$ (179,771)