Derivatives and Hedging Activity - Effect on Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivatives
Gain on derivative financial instruments	$ 33,989	$ 9,710
Interest rate swaps
Derivatives
Gain on derivative financial instruments	20,158	(45,125)
Interest rate swap guarantees
Derivatives
Gain on derivative financial instruments	351	(675)
Foreign exchange contracts
Derivatives
Gain on derivative financial instruments	13,602	53,265
Credit spread instrument
Derivatives
Gain on derivative financial instruments	$ (122)	$ 2,245