Loan Servicing (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Transfers and Servicing of Financial Assets [Abstract]
Serviced sold mortgage loans	$ 1,790,000,000	$ 1,410,000,000	$ 1,790,000,000	$ 1,410,000,000	$ 1,450,000,000
Serviced sold mortgage loans with recourse	2,000,000.0	2,400,000	2,000,000.0	2,400,000	2,300,000
Servicing fees included in other service income	1,000,000.0	$ 900,000	2,900,000	$ 2,700,000
Mortgage Loans Sold with Recourse, Reserve	$ 44,000		$ 44,000		$ 25,000