Investments - Schedule of Loans Modified to Borrowers Experiencing Financial Difficulty (Details) - Commercial mortgage loans - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Financing Receivable, Allowance for Credit Loss [Line Items] | ||||
| Amortized Cost Basis | $ 0 | $ 0 | $ 0 | |
| Percent of Total Class | 0.00% | |||
| Extension of term | 42 months | |||
| 30-89 Days Past Due | ||||
| Financing Receivable, Allowance for Credit Loss [Line Items] | ||||
| Amortized Cost Basis | $ 10 | 10 | 0 | |
| Percent of Total Class | 0.11% | |||
| 90+ Days Past Due | ||||
| Financing Receivable, Allowance for Credit Loss [Line Items] | ||||
| Amortized Cost Basis | $ 0 | $ 0 | ||