Mortgage Servicing Rights (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Mortgage Servicing Rights [Abstract]
Residential Mortgage Loans Serviced	$ 3,300,000,000		$ 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	6,400,000	$ 6,400,000
Valuation allowance increase	$ 0	$ 305,000	$ (1,339,000)	$ 4,341,000