Investment Securities (Narrative) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule of Investments [Line Items]
Other than Temporary Impairment Losses, Investments	$ 0	$ 0
Debt Securities, Available-for-sale, Amortized Cost	1,939,877,000		$ 1,727,363,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0		0
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Debt Securities, Available for Sale, Sold at Gain, Amortized Cost Amount	$ 0	$ 0
Debt Securities, Available-for-sale	1,839,103,000		1,754,140,000
Debt Securities, Available-for-sale, Unrealized Loss Position	1,657,224,000		840,832,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	102,493,000		9,514,000
Securities Available-for-Sale, 12 months or longer, Fair value	162,521,000		73,431,000
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	922,864,000		849,114,000
Debt Securities, Available-for-sale	863,734,000		854,463,000
Debt Securities, Available-for-sale, Unrealized Loss Position	819,760,000		407,084,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	59,461,000		8,088,000
Securities Available-for-Sale, 12 months or longer, Fair value	138,318,000		73,431,000
Collateral Pledged [Member]
Schedule of Investments [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 693,600,000		$ 733,700,000