Investments - Offsetting of Assets and Liabilities (Details) - Free-standing derivatives - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Asset derivatives:
Gross Amounts	$ 12.7	$ 6.8
Gross Amounts Offset in the Consolidated Balance Sheets	0.0	0.0
Net Amounts of Assets/ Liabilities Presented in the Consolidated Balance Sheets	12.7	6.8
Gross Amounts Not Offset in the Consolidated Balance Sheets, Financial Instruments	0.0	0.0
Gross Amounts Not Offset in the Consolidated Balance Sheets, Cash Collateral Received	12.0	5.9
Net Amount	$ 0.7
Net Amount		$ 0.9