Accumulated Other Comprehensive Loss - Reclassifications from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Out Of Accumulated Other Comprehensive Loss
Losses on securities transactions, net	$ (32)	$ (765)
Tax effect	(57,196)	(13,184)
Total net of tax	113,330	41,965
Interest expense	(101,576)	(59,897)
Total reclassifications, net of tax	(289)	(1,680)
Unrealized losses on AFS securities before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Total reclassifications, net of tax	(26)
Unrealized losses on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Total reclassifications, net of tax	(208)
Defined Benefit Pension Plan
Reclassification Out Of Accumulated Other Comprehensive Loss
Amortization of net loss	(78)	(157)
Tax effect	23	45
Total reclassifications, net of tax	(55)	(112)
Reclassification Out of Accumulated Other Comprehensive Income (Loss)
Reclassification Out Of Accumulated Other Comprehensive Loss
Interest expense	(290)	(1,451)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) | Unrealized losses on AFS securities before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Losses on securities transactions, net	(32)	(743)
Tax effect	6	211
Total net of tax	(26)	(532)
Reclassification Out of Accumulated Other Comprehensive Income (Loss) | Unrealized losses on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Tax effect	82	415
Total net of tax	(208)	(1,036)
Interest expense	$ (290)	$ (1,451)