Derivatives (Offsetting of Derivatives) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivative assets
Derivative assets - Fair value	$ 457,317	$ 602,754
Less: Master netting agreements	(100,454)	(93,063)
Less: Cash collateral received/pledged	(7,781)	(8,449)
Net derivative assets	349,082	501,242
Less: Security Collateral Received	0	(35)
Net Amount	349,082	501,207
Contracts not subject to master netting arrangements, gross amounts recognized	532	1,100
Derivative, cash collateral received, including amount offset by fair value assets, and excess cash amount	11,900	15,800
Amount used to offset against derivative assets	7,781	8,449
Derivative liabilities
Gross amounts recognized	344,135	424,828
Less: Master netting agreements	(100,454)	(93,063)
Less: Cash collateral received/pledged	(86,233)	(91,634)
Net derivative liabilities	157,448	240,131
Less: Security Collateral Pledged	(64,816)	(221,150)
Net Amount	92,632	18,981
Contracts not subject to master netting arrangements, gross amounts recognized	151	220
Derivative, cash collateral posted against derivative liabilities, including amount offset the derivative fair value liabilities, and excess cash amount	90,800	91,600
Amount used to offset against derivative liabilities	$ 86,233	$ 91,634