Income Taxes (Summary of Operating and Capital Loss Carryforwards) (Details) $ in Millions	Sep. 30, 2023 USD ($)
U.S. State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 237.1
Capital loss carryforwards	35.2
U.S. Federal
Operating Loss Carryforwards [Line Items]
Capital loss carryforwards	86.3
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	325.9
Capital loss carryforwards	$ 197.8