Investments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) Security	Dec. 31, 2018 USD ($) Security
Available-for-sale, securities in unrealized loss positions, qualitative disclosure, number of positions, total | Security	415	552
Securities available-for-sale	$ 563,628,000	$ 560,479,000
Available-for-sale securities, amortized cost basis, total	566,930,000	569,942,000
Low Income Housing Tax Credit Fund Investments [Member]
Investment, book balance	5,500,000
Investment, remaining commitments for additional capital contributions	1,900,000
Investment, tax credit	133,000
Investment, amortization expense	450,000
States and Political Subdivisions [Member]
Securities available-for-sale	145,712,000	140,534,000
Available-for-sale securities, amortized cost basis, total	143,483,000	$ 140,181,000
States and Political Subdivisions [Member]
Available-for-sale securities, amortized cost basis, total	$ 2,570,000