Investments Equity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Equity Securities [Line Items]
Equity securities, cost	$ 212.6	$ 112.4
Equity Securities, FV-NI	338.8	208.5
Industrial and miscellaneous
Equity Securities [Line Items]
Equity securities, cost	170.5	94.1
Equity Securities, FV-NI	283.1	179.1
Other equities
Equity Securities [Line Items]
Equity securities, cost	42.1	18.3
Equity Securities, FV-NI	$ 55.7	$ 29.4