Derivatives - Gains/(Losses) on Derivatives Associated with Interest Rate Risk Management Activities (Details) - Hedging Instruments And Hedged Items - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Customer Interest Rate Contracts Hedging | Customer interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) related to interest rate derivatives	$ 15,844	$ 50,706	$ 211,396	$ 79,818
Customer Interest Rate Contracts Hedging | Offsetting upstream interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) related to interest rate derivatives	(15,844)	(50,706)	(211,396)	(79,818)
Debt Hedging | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Gains (losses) related to interest rate derivatives	(737)	6,697	4,197	10,976
Debt Hedging | Term Borrowings
Derivative Instruments, Gain (Loss) [Line Items]
Gains/(Losses) related to term borrowings	$ 720	$ (6,605)	$ (3,745)	$ (10,871)