Investments (Limited Partnerships and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Real Estate [Line Items] | ||
| Real Estate Investments, Joint Ventures | $ 4,427 | $ 3,747 |
| Equity Method Investments | ||
| Real Estate [Line Items] | ||
| Real Estate Investments, Joint Ventures | 2,249 | 1,543 |
| Limited partnership Fair Value Member | ||
| Real Estate [Line Items] | ||
| Real Estate Investments, Joint Ventures | 926 | 925 |
| Corporate Joint Venture | ||
| Real Estate [Line Items] | ||
| Real Estate Investments, Joint Ventures | 1,121 | 1,207 |
| Limited Partnership Cost Method | ||
| Real Estate [Line Items] | ||
| Real Estate Investments, Joint Ventures | 68 | 72 |
| Corporate Joint Venture Fair Value Method | ||
| Real Estate [Line Items] | ||
| Real Estate Investments, Joint Ventures | $ 63 | $ 0 |