Acquisition PCI Loans Acquired (Details) - Blue Hills Bancorp, Inc. [Member] $ in Thousands	Apr. 01, 2019 USD ($)
Business Acquisition [Line Items]
Contractually required principal and interest at acquisition	$ 14,849
Contractual cash flows not expected to be collected	(5,717)
Expected cash flows at acquisition	9,132
Interest component of expected cash flows	(1,464)
Basis in PCI loans at acquisition - estimated fair value	$ 7,668