Allowance for Credit Losses - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Allowance for Credit Losses
Available for sale debt securities past due	$ 0.0		$ 0.0
Provision (reversal) in allowance on individually evaluated loans	(1.3)	$ (1.0)	(1.0)	$ 0.4
Provision (reversal) in allowance on collectively evaluated loans	6.6	(27.7)	6.4	(34.2)
Net charge-offs	$ 1.2	$ 0.5	$ 1.5
Net recoveries				$ 0.1