Investment Securities - Summary of Unrealized Losses of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	$ 34,639	$ 19,478
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	582	117
Held-to-maturity, Securities with losses over 12 months, Fair Value	10,877	12,090
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	606	451
Held-to-maturity, Total, Fair Value	45,516	31,568
Held-to-maturity, Total, Gross Unrealized Loss	1,188	568
Obligations of state and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	6,318	6,340
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	95	22
Held-to-maturity, Securities with losses over 12 months, Fair Value	0	0
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	0	0
Held-to-maturity, Total, Fair Value	6,318	6,340
Held-to-maturity, Total, Gross Unrealized Loss	95	22
GSE mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	26,853	11,201
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	475	89
Held-to-maturity, Securities with losses over 12 months, Fair Value	4,438	4,961
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	212	130
Held-to-maturity, Total, Fair Value	31,291	16,162
Held-to-maturity, Total, Gross Unrealized Loss	687	219
Collateralized mortgage obligations: residential
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	0	0
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	0	0
Held-to-maturity, Securities with losses over 12 months, Fair Value	6,439	7,129
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	394	321
Held-to-maturity, Total, Fair Value	6,439	7,129
Held-to-maturity, Total, Gross Unrealized Loss	394	321
Collateralized mortgage obligations: commercial
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	1,468	1,937
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	12	6
Held-to-maturity, Securities with losses over 12 months, Fair Value	0	0
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	0	0
Held-to-maturity, Total, Fair Value	1,468	1,937
Held-to-maturity, Total, Gross Unrealized Loss	$ 12	$ 6