Accumulated Other Comprehensive Loss - Reclassification from Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Reclassification Out Of Accumulated Other Comprehensive Loss
(Losses) gains on securities transactions, net	$ (309)		$ 375		$ (1,381)	$ 476
Tax effect	(36,552)		(42,881)		(75,866)	(82,202)
Net income	96,413	$ 116,728	120,512	$ 115,710	213,141	236,222
Interest expense	(34,787)		(32,741)		(57,576)	(71,872)
Amortization of actuarial net loss	22,284		11,341		37,646	23,743
Amounts Reclassified from Accumulated Other Comprehensive Loss
Reclassification Out Of Accumulated Other Comprehensive Loss
Net income	(53)		(888)		(561)	(1,863)
Interest expense	116		(749)		(426)	(1,664)
Amounts Reclassified from Accumulated Other Comprehensive Loss | Unrealized (losses) gains on AFS securities before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
(Losses) gains on securities transactions, net	0		(103)		14	(162)
Tax effect	0		27		(4)	42
Net income	0		(76)		10	(120)
Amounts Reclassified from Accumulated Other Comprehensive Loss | Unrealized gains (losses) on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Tax effect	(36)		215		120	479
Net income	80		(534)		(306)	(1,185)
Interest expense	116		(749)		(426)	(1,664)
Amounts Reclassified from Accumulated Other Comprehensive Loss | Defined benefit pension plan
Reclassification Out Of Accumulated Other Comprehensive Loss
Tax effect	51		109		102	217
Net income	(133)		(278)		(265)	(558)
Amortization of actuarial net loss	$ (184)		$ (387)		$ (367)	$ (775)