Guaranteed Benefit Features - Separate Accounts by Investment Type (Details) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Equity funds | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | $ 2,000 | $ 1,904 |
| Bond funds | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | 190 | 184 |
| Balanced funds | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | 341 | 329 |
| Money market funds | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | 49 | 46 |
| Other | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | 10 | 10 |
| Equity securities | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | 2,590 | 2,473 |
| Fixed income securities | ||
| Fair Value, Separate Account Investment [Line Items] | ||
| Equity securities (including mutual funds) | $ 8,400 | $ 7,400 |