Derivatives - Gains/(Losses) on Derivatives Associated with Interest Rate Risk Management Activities (Details) - Hedging Instruments And Hedged Items - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Customer Interest Rate Contracts Hedging | Customer interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) related to interest rate derivatives	$ (14,050)	$ 44,375	$ 197,346	$ 124,193
Customer Interest Rate Contracts Hedging | Offsetting upstream interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) related to interest rate derivatives	14,050	(44,375)	(197,346)	(124,193)
Debt Hedging | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) related to interest rate derivatives	(1,421)	1,994	2,776	12,969
Debt Hedging | Term Borrowings
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(Losses) related to term borrowings	$ 1,412	$ (2,004)	$ (2,333)	$ (12,876)