Investment Securities - Summary of Maturities (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Available for sale, Amortized Cost
Within one year	$ 300
After one year, but within five	13,311
After five years, but within ten	32,703
After ten years	126,005
Total	172,319
Available for sale, Fair Value
Within one year	301
After one year, but within five	13,768
After five years, but within ten	32,449
After ten years	125,214
Total	171,732
Carrying value of investment securities pledged	$ 76,000