Investments (Limited Partnerships and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Real Estate [Line Items] | ||
| Limited partnerships and real estate joint ventures | $ 4,093 | $ 3,747 |
| Equity Method Investments | ||
| Real Estate [Line Items] | ||
| Limited partnerships and real estate joint ventures | 1,878 | 1,543 |
| Limited partnership Fair Value Member | ||
| Real Estate [Line Items] | ||
| Limited partnerships and real estate joint ventures | 935 | 925 |
| Corporate Joint Venture | ||
| Real Estate [Line Items] | ||
| Limited partnerships and real estate joint ventures | 1,193 | 1,207 |
| Limited Partnership Cost Method | ||
| Real Estate [Line Items] | ||
| Limited partnerships and real estate joint ventures | 71 | 72 |
| Corporate Joint Venture Fair Value Method | ||
| Real Estate [Line Items] | ||
| Limited partnerships and real estate joint ventures | $ 16 | $ 0 |