Pledged and Restricted Assets (Accepted Collateral) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Jun. 30, 2022
Financial Instruments Owned and Pledged as Collateral [Line Items]
Total Collateral Accepted	$ 2,109.8	$ 4,874.5
Fair value of securities received as collateral that have been resold or repledged		3,692.0
Securities received as collateral, amount repledged and sold	1,419.0
Reverse repurchase agreements
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral that may be repledged or sold	1,457.0	4,157.3
Reverse repurchase agreements	650.0	700.0
DERIVATIVE CONTRACTS
Financial Instruments Owned and Pledged as Collateral [Line Items]
Collateral that may be repledged or sold	$ 2.8	$ 17.2