Premises, Furniture, and Equipment - Accretion of Operating Leases (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Property, Plant and Equipment [Abstract]
One year or less	$ 1,011
After one year to two years	742
After two years to three years	648
After three years to four years	648
After four years to five years	648
After five years	3,511
Total accretion	$ 7,208