Segment Information (Details) - Assets by Segment - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Assets by segment
Total assets	$ 129,315	$ 125,978
Reportable Segments [Member]
Assets by segment
Total assets	128,333	125,115
Reportable Segments [Member] \| Business Insurance [Member]
Assets by segment
Total assets	95,686	93,565
Reportable Segments [Member] \| Bond & Specialty Insurance [Member]
Assets by segment
Total assets	12,243	11,478
Reportable Segments [Member] \| Personal Insurance [Member]
Assets by segment
Total assets	20,404	20,072
Other assets [Member]
Assets by segment
Total assets	$ 982	$ 863

Amount of asset recognized for present right to economic benefit.

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+ Details