Investment Securities (Narrative) (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($) item	Dec. 31, 2019 USD ($) security item	Dec. 31, 2018 USD ($) security item	Dec. 31, 2017 USD ($) security
Investment Securities [Line Items]
Number of holdings greater than 10 percent of stockholders equity | item	0	0	0
Income tax expense (benefit) related to net realized gains (losses)		$ 4,000	$ (2,907,000)	$ (782,000)
Restricted investment securities	$ 382,963,000	382,963,000	$ 342,712,000
Held-to-maturity securities, gain or loss	0
Held-to-maturity securities transferred to available-for-sale		$ 3,949,000
Accounting Standards Update 2019-04 [Member]
Investment Securities [Line Items]
Held-to-maturity securities transferred to available-for-sale	$ 3,949,000
Municipal Security [Member]
Investment Securities [Line Items]
Held-to-maturity securities, Number of sales | security				1
Mortgage-Backed Securities [Member]
Investment Securities [Line Items]
Held-to-maturity securities, Number of sales | security		0	0
State And Municipals [Member]
Investment Securities [Line Items]
Held-to-maturity securities, Carrying value				$ 354,000
Held-to-maturity securities, Realized gain				$ 1,000