Investment Securities - Summary of Unrealized Losses of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	$ 5,287	$ 31,802
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	59	362
Held-to-maturity, Securities with losses over 12 months, Fair Value	7,596	8,645
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	223	323
Held-to-maturity, Total, Fair Value	12,883	40,447
Held-to-maturity, Total, Gross Unrealized Loss	282	685
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		8,054
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss		39
Held-to-maturity, Securities with losses over 12 months, Fair Value		0
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss		0
Held-to-maturity, Total, Fair Value		8,054
Held-to-maturity, Total, Gross Unrealized Loss		39
GSE mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value	5,287	19,408
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss	59	311
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	5,287	19,408
Held-to-maturity, Total, Gross Unrealized Loss	59	311
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	7,596	8,645
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss	223	323
Held-to-maturity, Total, Fair Value	7,596	8,645
Held-to-maturity, Total, Gross Unrealized Loss	$ 223	323
Collateralized mortgage obligations: commercial
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity, Securities with losses under 12 months, Fair Value		4,340
Held-to-maturity, Securities with losses under 12 months, Gross Unrealized Loss		12
Held-to-maturity, Securities with losses over 12 months, Fair Value		0
Held-to-maturity, Securities with losses over 12 months, Gross Unrealized Loss		0
Held-to-maturity, Total, Fair Value		4,340
Held-to-maturity, Total, Gross Unrealized Loss		$ 12