Employee Benefits (Schedule of plan's funded status and amounts recognized in consolidated statement of financial condition) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Employee Benefits
Projected and accumulated benefit obligation	$ (23,964)	$ (20,953)
Plan assets at fair value	22,634	20,628
Funded status included in accrued expenses and other liabilities	$ (1,330)	$ (325)