Investment Securities - Summary of Unrealized Losses of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	$ 40,209	$ 19,478
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	505	117
Held-to-maturity, Securities with losses over 12 months, Fair Value	11,392	12,090
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	605	451
Held-to-maturity, Total, Fair Value	51,601	31,568
Held-to-maturity, Total, Gross Unrealized Loss	1,110	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	9,893	6,340
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	113	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	9,893	6,340
Held-to-maturity, Total, Gross Unrealized Loss	113	22
GSE mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	28,673	11,201
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	380	89
Held-to-maturity, Securities with losses over 12 months, Fair Value	4,658	4,961
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	218	130
Held-to-maturity, Total, Fair Value	33,331	16,162
Held-to-maturity, Total, Gross Unrealized Loss	598	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	6,734	7,129
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	387	321
Held-to-maturity, Total, Fair Value	6,734	7,129
Held-to-maturity, Total, Gross Unrealized Loss	387	321
Collateralized mortgage obligations: commercial
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	1,643	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	1,643	1,937
Held-to-maturity, Total, Gross Unrealized Loss	$ 12	$ 6