Securities - Summary of Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value
Fair Value	$ 226,018	$ 197,475
Less than 12 Months, Fair Value	137,860	195,789
12 Months or More, Fair Value	88,158	1,686
Unrealized Loss
Unrealized Loss	3,628	4,130
Less than 12 Months, Unrealized Loss	1,018	4,103
12 Months or More, Unrealized Loss	2,610	27
Federal agencies and GSEs
Fair Value
Fair Value	99,133	89,597
Less than 12 Months, Fair Value	45,474	89,597
12 Months or More, Fair Value	53,659	0
Unrealized Loss
Unrealized Loss	2,127	2,387
Less than 12 Months, Unrealized Loss	321	2,387
12 Months or More, Unrealized Loss	1,806	0
Mortgage-backed and CMOs
Fair Value
Fair Value	90,806	57,762
Less than 12 Months, Fair Value	64,449	56,076
12 Months or More, Fair Value	26,357	1,686
Unrealized Loss
Unrealized Loss	1,140	938
Less than 12 Months, Unrealized Loss	533	911
12 Months or More, Unrealized Loss	607	27
State and municipal
Fair Value
Fair Value	34,550	47,221
Less than 12 Months, Fair Value	27,442	47,221
12 Months or More, Fair Value	7,108	0
Unrealized Loss
Unrealized Loss	347	782
Less than 12 Months, Unrealized Loss	159	782
12 Months or More, Unrealized Loss	188	0
Corporate
Fair Value
Fair Value	1,529	2,895
Less than 12 Months, Fair Value	495	2,895
12 Months or More, Fair Value	1,034	0
Unrealized Loss
Unrealized Loss	14	23
Less than 12 Months, Unrealized Loss	5	23
12 Months or More, Unrealized Loss	$ 9	$ 0