Mortgage Servicing Rights (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Mortgage Servicing Rights [Abstract]
Residential Mortgage Loans Serviced	$ 3,300,000,000		$ 3,300,000,000
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset	2,100,000	$ 2,100,000
Valuation allowance increase	$ (3,123,000)	$ 2,967,000