Investments - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2024 USD ($) Security	Dec. 31, 2023 USD ($) Security
Summary of Investment Holdings [Line Items]
Number of securities in unrealized loss position | Security	1,059	1,063
Securities lending rate of collateral required	1.02
Debt Securities
Summary of Investment Holdings [Line Items]
Assets held by insurance regulators	$ 14	$ 14
Foreign government and agency securities
Summary of Investment Holdings [Line Items]
Securities lending rate of collateral required	1.05
Loaned securities
Summary of Investment Holdings [Line Items]
Securities lending rate of collateral required	1
Securities received as collateral	$ 18	$ 61