Accumulated Other Comprehensive Loss - Reclassifications from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Out Of Accumulated Other Comprehensive Loss
Losses on securities transactions, net	$ (40)	$ (32)
Tax effect	(29,129)	(57,196)
Total net of tax	87,268	113,330
Interest expense	(98,454)	(101,576)
Total reclassifications, net of tax	(637)	(289)
Unrealized losses on AFS securities before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Total reclassifications, net of tax	(27)
Unrealized losses on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Total reclassifications, net of tax	(438)
Defined benefit pension plan
Reclassification Out Of Accumulated Other Comprehensive Loss
Amortization of actuarial net loss	(236)	(78)
Tax effect	64	23
Total reclassifications, net of tax	(172)	(55)
Amounts Reclassified from Accumulated Other Comprehensive Loss
Reclassification Out Of Accumulated Other Comprehensive Loss
Interest expense	(615)	(290)
Amounts Reclassified from Accumulated Other Comprehensive Loss | Unrealized losses on AFS securities before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Losses on securities transactions, net	(40)	(32)
Tax effect	13	6
Total net of tax	(27)	(26)
Amounts Reclassified from Accumulated Other Comprehensive Loss | Unrealized losses on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Tax effect	177	82
Total net of tax	(438)	(208)
Interest expense	$ (615)	$ (290)