Accumulated Other Comprehensive Loss - Reclassifications from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Out Of Accumulated Other Comprehensive Loss
(Losses) gains on securities transactions, net	$ (41)		$ 11		$ (81)	$ (21)
Tax effect	(33,466)		(27,532)		(62,595)	(84,728)
Total net of tax	95,601	$ 87,268	76,468	$ 113,330	182,869	189,798
Interest expense	(65,966)		(107,508)		(164,420)	(209,084)
Total reclassifications, net of tax	105		(321)		(532)	(610)
Unrealized (losses) gains on AFS securities before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Total reclassifications, net of tax	(31)				(58)
Unrealized gains (losses) on derivatives (cash flow hedges) before tax
Reclassification Out Of Accumulated Other Comprehensive Loss
Total reclassifications, net of tax	308				(130)
Defined benefit pension plan
Reclassification Out Of Accumulated Other Comprehensive Loss
Amortization of actuarial net loss	(229)		(78)		(465)	(156)
Tax effect	57		23		121	46
Total reclassifications, net of tax	(172)		(55)		(344)	(110)
Amounts Reclassified from Accumulated Other Comprehensive Loss
Reclassification Out Of Accumulated Other Comprehensive Loss
Interest expense	438		(383)		(177)	(673)
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	(41)		11		(81)	(21)
Tax effect	10		(3)		23	3
Total net of tax	(31)		8		(58)	(18)
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	(130)		109		47	191
Total net of tax	308		(274)		(130)	(482)
Interest expense	$ 438		$ (383)		$ (177)	$ (673)