Investments (Limited Partnerships and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Real Estate [Line Items]
Real Estate Investments, Joint Ventures	$ 2,473	$ 2,327
Equity Method Investments
Real Estate [Line Items]
Real Estate Investments, Joint Ventures	928	934
Limited partnership Fair Value Member
Real Estate [Line Items]
Real Estate Investments, Joint Ventures	768	683
Corporate Joint Venture
Real Estate [Line Items]
Real Estate Investments, Joint Ventures	715	661
Limited Partnership Cost Method
Real Estate [Line Items]
Real Estate Investments, Joint Ventures	$ 62	$ 49