Securities - Amortized Costs and Fair Values of Securities Held to Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 15,778	$ 9,200
Gross Unrealized Gains	660	112
Gross Unrealized Losses	(22)	(19)
Estimated Fair Value	16,416	9,293
U.S. Government agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	5,000	5,000
Gross Unrealized Gains	18	46
Gross Unrealized Losses	0	0
Estimated Fair Value	5,018	5,046
Municipals
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,778	4,200
Gross Unrealized Gains	642	66
Gross Unrealized Losses	(22)	(19)
Estimated Fair Value	$ 11,398	$ 4,247