Investment Securities (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale	$ 1,248,787,000		$ 1,332,842,000
Debt Securities, Available-for-sale, Unrealized Loss Position	1,078,968,000		1,206,855,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	86,912,000		87,155,000
Securities Available-for-Sale, 12 months or longer, Fair value	1,003,286,000		1,150,640,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0
Other than Temporary Impairment Losses, Investments	0	$ 0
Debt Securities, Available-for-sale, Amortized Cost	$ 1,334,973,000		1,418,770,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Gain (Loss) on Sale of Investments	$ 398,000	$ 0
Debt securities available for sale, securities sold	31,200,000
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale	603,009,000		635,475,000
Debt Securities, Available-for-sale, Unrealized Loss Position	601,810,000		634,261,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	69,466,000		68,193,000
Securities Available-for-Sale, 12 months or longer, Fair value	601,810,000		634,261,000
Debt Securities, Available-for-sale, Amortized Cost	672,462,000		703,645,000
USGovernmentSponsored asset backed securities and US Treasury obligations
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	69,500,000
Collateral Pledged [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 762,100,000		$ 602,000,000