Derivatives (Offsetting of Derivatives) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative assets
Derivative assets - Fair value	$ 694,010	$ 602,754
Less: Master netting agreements	(102,515)	(93,063)
Less: Cash collateral received/paid	(62,968)	(8,449)
Net derivative assets	528,527	501,242
Less: Security Collateral Received	0	(35)
Net Amount	528,527	501,207
Contracts not subject to master netting arrangements, gross amounts recognized	1,200	1,100
Derivative, cash collateral received, including amount offset by fair value assets, and excess cash amount	67,100	15,800
Amount used to offset against derivative assets	(62,968)	(8,449)
Derivative liabilities
Gross amounts recognized	561,788	424,828
Less: Master netting agreements	(102,515)	(93,063)
Less: Cash collateral received/paid	(240,104)	(91,634)
Net derivative liabilities	219,169	240,131
Less: Security Collateral Pledged	(157,315)	(221,150)
Net Amount	61,854	18,981
Contracts not subject to master netting arrangements, gross amounts recognized	1,400	220
Derivative, cash collateral posted against derivative liabilities, including amount offset the derivative fair value liabilities, and excess cash amount	240,100	91,600
Amount used to offset against derivative liabilities	$ (240,104)	$ (91,634)