Loans (Narrative) (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($) contract item loan	Jun. 30, 2019 USD ($) contract	Jun. 30, 2020 USD ($) loan item	Jun. 30, 2019 USD ($) loan	Dec. 31, 2019 USD ($) item loan
Financing Receivable, Past Due [Line Items]
Allowance for loan losses, TDR	$ 0		$ 0		$ 14,000
Number of days past due to be considered default			90 days
Minimum prior year principal balance of commercial Real estate loans required to be reviewed annually					80.00%
Number of contracts with payment default | contract	0	0
Number of commitments to lend | item	0		0		0
Number of loans in the process of foreclosure | loan			0		0
Number of loans modified | loan			0	0
Accrued interest receivable	$ 12,830,000		$ 12,830,000		$ 8,409,000
Allowance for credit losses, beginning balance	34,105,000	$ 30,199,000	29,289,000	$ 30,838,000	30,838,000
Outstanding loan balance	$ 621,289,000		$ 621,289,000
Number of Loans | loan	775		775
Accrued Interest	$ 6,237,000		$ 6,237,000
Residential Mortgages [Member]
Financing Receivable, Past Due [Line Items]
Real estate acquired through foreclosure	0		0		0
Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Allowance for credit losses, beginning balance	$ 1,931,000	$ 1,047,000	$ 1,493,000	$ 1,158,000	$ 1,158,000