Premises and Equipment - Maturity Analysis of Operating Lease Liabilities and Reconciliation of Undiscounted Cash Flows (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Lease payments due:
Within one year	$ 1,537
After one but within two years	1,546
After two but within three years	1,548
After three but within four years	1,447
After four but within five years	1,313
After five years	8,545
Total undiscounted cash flows	15,936
Discount on cash flows	(2,778)
Operating lease, liability	$ 13,158