Investments (Limited Partnerships and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	$ 3,228	$ 3,067
Equity Method Investments
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	1,146	1,067
Limited partnership Fair Value Member
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	963	966
Corporate Joint Venture
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	1,054	970
Limited Partnership Cost Method
Real Estate [Line Items]
Limited partnerships and real estate joint ventures	$ 65	$ 64