Investment Securities - Narrative (Details) $ in Thousands	Jun. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($)
Investments, Debt and Equity Securities [Abstract]
Carrying value of securities pledged as collateral	$ 1,100,278	$ 503,427
Book value of securities sold under agreements to repurchase	171,346	182,856
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	165	2,211
Held-to-maturity unrealized losses	74	545
State and municipal
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 138	807
Number of securities in unrealized loss positions | security	13
Held-to-maturity unrealized losses	$ 43	107
Held-to-maturity, number of securities in unrealized loss positions | security	2
U.S. Government-sponsored mortgage-backed securities
Schedule of Available for sale Securities and Held to maturity Securities [Line Items]
Gross unrealized losses	$ 27	1,404
Number of securities in unrealized loss positions | security	1
Held-to-maturity unrealized losses	$ 31	$ 401
Held-to-maturity, number of securities in unrealized loss positions | security	3