Amount of asset at fair value held for benefit of separate account policyholder.

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Name:	us-gaap_SeparateAccountAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Separate accounts (Fair value of assets) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 6,810	$ 6,231	$ 5,996
Separate Account, Cash and Cash Equivalents
Fair Value, Separate Account Investment [Line Items]
Separate account assets	103		75
Fixed maturities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	76		77
Mutual funds
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 6,631		$ 5,844