Other Real Estate Owned (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Repossessed Assets [Abstract]
Real Estate Acquired Through Foreclosure, Valuation Adjustments	$ 0.0	$ 0.1
Real Estate Acquired Through Foreclosure [Roll Forward]
Balance at beginning of year	2.5	8.5	$ 14.4
OREO acquired through acquisitions	0.0	0.0	2.4
Additions	0.9	3.3	14.1
Valuation adjustments	0.0	(0.1)	(0.9)
Dispositions	(1.4)	(9.2)	(21.8)
Balance at end of year	2.0	2.5	8.5
Real Estate Acquired Through Foreclosure, Improvements	0.0	0.0	0.3
Write-downs of OREO	0.0	(0.1)	$ (0.9)
Mortgage Loans in Process of Foreclosure, Amount	0.2	0.2
Carrying value of foreclosed OREO	$ 0.2	$ 0.0