Securities Securities (Reconciliation of amortized cost of held to maturity securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	$ 861,821	$ 724,512
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	20,216	28,007
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(4,236)	(342)
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	877,801	752,177
Small Business Administration Pooled Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	24,316	26,917
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	1,326	1,445
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	25,642	28,362
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	1,500	1,500
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	8	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	(2)
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	1,508	1,498
Collateralized Debt Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	418,112	335,993
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	6,347	8,466
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(2,618)	(340)
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	421,841	344,119
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	381,030	356,085
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	12,507	18,036
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(1,495)	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	392,042	374,121
US Treasury Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	3,010	4,017
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	28	60
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	3,038	4,077
U.S. government agency securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-maturity	33,853	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(123)	0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0
Debt Securities, Held-to-maturity, Fair Value	$ 33,730	$ 0