Investments (Limited Partnerships and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	$ 2,697	$ 2,635
Equity Method Investments
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	923	925
Limited partnership Fair Value Member
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	893	856
Corporate Joint Venture
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	810	783
Limited Partnership Cost Method
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	$ 71	$ 71