Derivative Financial Instruments (Summary of Interest Rate Derivatives) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Derivative Assets
Derivative Assets	$ 153,534	$ 165,008	$ 253,509
Derivative Liabilities
Gross Amounts Recognized	122,107	123,000	200,758
Interest rate derivatives
Derivative Assets
Derivative Assets	139,701	152,493	206,236
Less: Amounts offset in the Statements of Condition	0	0	0
Net amount presented in the Statements of Condition	139,701	152,493	206,236
Offsetting Derivative Positions	(19,557)	(52,832)	(60,593)
Collateral Posted	(70,807)	(3,530)	0
Net Credit Exposure	49,337	96,131	145,643
Derivative Liabilities
Gross Amounts Recognized	120,079	119,907	196,091
Less: Amounts offset in the Statements of Condition	0	0	0
Net amount presented in the Statements of Condition	120,079	119,907	196,091
Offsetting Derivative Positions	(19,557)	(52,832)	(60,593)
Collateral Posted	(257)	(55,201)	(125,818)
Net Credit Exposure	$ 100,265	$ 11,874	$ 9,680