Investment Securities - Narrative (Details)	Sep. 30, 2019 USD ($) security	Dec. 31, 2018 USD ($)
Investments, Debt and Equity Securities [Abstract]
Carrying value of securities pledged as collateral	$ 632,275,000	$ 416,155,000
Book value of securities sold under agreements to repurchase	187,472,000	116,691,000
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	1,691,000	14,253,000
Held-to-maturity unrealized losses	604,000	4,741,000
State and municipal
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 634,000	5,854,000
Number of securities in unrealized loss positions | security	26
Held-to-maturity unrealized losses	$ 40,000	872,000
Held-to-maturity, number of securities in unrealized loss positions | security	2
U.S. Government-sponsored agency securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 26,000	3,000
Number of securities in unrealized loss positions | security	2
Held-to-maturity unrealized losses	$ 95,000	545,000
Held-to-maturity, number of securities in unrealized loss positions | security	5
Foreign investment
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 0
Held-to-maturity unrealized losses	$ 7,000	1,000
Held-to-maturity, number of securities in unrealized loss positions | security	1
U.S. Government-sponsored mortgage-backed securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 1,031,000	8,396,000
Number of securities in unrealized loss positions | security	31
Held-to-maturity unrealized losses	$ 462,000	$ 3,323,000
Held-to-maturity, number of securities in unrealized loss positions | security	16