Restricted Equity Securities (Investments in Restricted Equity Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Restricted equity securities
Restricted equity securities	$ 53,818	$ 61,751
FHLBB stock
Restricted equity securities
Restricted equity securities	35,482	43,655
FRB stock
Restricted equity securities
Restricted equity securities	18,084	17,995
Other restricted equity securities
Restricted equity securities
Restricted equity securities	$ 252	$ 101