Derivatives and Hedging Activity - Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	$ 52,566	$ 40,555
Fair Value of Derivatives in a Liability Position	15,615	41,324
Interest rate contracts
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	22,684	33,841
Fair Value of Derivatives in a Liability Position	2,054	4
Interest rate swap guarantees
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	0	0
Fair Value of Derivatives in a Liability Position	417	849
Foreign exchange contracts
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	29,882	6,585
Fair Value of Derivatives in a Liability Position	12,896	39,951
Credit index instruments
Fair value of derivative instruments
Fair Value of Derivatives in an Asset Position	0	129
Fair Value of Derivatives in a Liability Position	$ 248	$ 520