Separate accounts (Fair Value of Assets) (Details) - USD ($) $ in Millions |
Sep. 30, 2023 |
Dec. 31, 2022 |
---|---|---|
Fair Value, Separate Account Investment [Line Items] | ||
Separate account assets | $ 5,306 | $ 5,190 |
Separate Account, Cash and Cash Equivalents | ||
Fair Value, Separate Account Investment [Line Items] | ||
Separate account assets | 88 | 141 |
Separate Account, equity securities and mutual funds | ||
Fair Value, Separate Account Investment [Line Items] | ||
Separate account assets | 5,129 | 4,960 |
Separate Account, Non-U.S. Government Treasuries | ||
Fair Value, Separate Account Investment [Line Items] | ||
Separate account assets | $ 89 | $ 89 |