Accumulated Other Comprehensive Income (Loss) - Reclassifications out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassifications out of accumulated other comprehensive income, net of tax
Interest expense	$ (24,946)	$ (22,628)	$ (62,740)	$ (65,554)
Other-than-temporary impairment losses			0
Provision for income taxes	(23,233)	(12,998)	(2,741)	(34,455)
Net income	95,221	51,565	34,396	137,392
Amount Reclassified from Accumulated Other Comprehensive Loss
Reclassifications out of accumulated other comprehensive income, net of tax
Net income	2,685	(529)	4,780	7,785
Gains and Losses on Cash Flow Hedges | Amount Reclassified from Accumulated Other Comprehensive Loss | Interest rate contracts
Reclassifications out of accumulated other comprehensive income, net of tax
Interest expense	3,457	(241)	6,143	(585)
Provision for income taxes	(760)	53	(1,351)	128
Net income	2,697	(188)	4,792	(457)
Unrealized Gains and Losses on Securities Available for Sale | Amount Reclassified from Accumulated Other Comprehensive Loss
Reclassifications out of accumulated other comprehensive income, net of tax
Securities (gains) losses, net	(15)	(437)	(15)	2,679
Provision for income taxes	3	96	3	(590)
Net income	$ (12)	$ (341)	$ (12)	2,089
Benefit Plans | Amount Reclassified from Accumulated Other Comprehensive Loss
Reclassifications out of accumulated other comprehensive income, net of tax
Salaries and employee benefits /Pension Plan Termination Expense				7,888
Provision for income taxes				(1,735)
Net income				$ 6,153