Investments - Variable Interest Entity (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Variable Interest Entity
Total Assets	$ 27,721.5	$ 27,619.0
Total Liabilities	13,951.0	13,954.9
RMMC/RMBC
Variable Interest Entity
Total Assets	237.0	204.9
Total Liabilities	23.0	19.1
Other
Variable Interest Entity
Total Assets	55.8	70.8
Total Liabilities	$ 15.7	$ 14.8