Acquisitions - Summary of allocation of purchase price (Details) - US MidCorp and Entertainment $ in Millions	Aug. 01, 2024 USD ($)
Purchase price
Business acquisition, cash paid	$ 450
Assets Acquired
Cash and investments, at fair value	2,332
Premiums receivable	290
Other assets acquired	158
Total assets acquired	3,341
Liabilities Acquired
Reserves for losses and loss adjustment expenses	2,404
Unearned premiums	632
Other liabilities acquired	121
Total liabilities acquired	3,157
Net assets acquired	184
Goodwill	266
Deferred tax asset, goodwill and intangibles	568
Net deferred tax asset, loss reserves and unearned premium	23
Reserves For Losses And Loss Adjustment Expenses
Liabilities Acquired
Loss reserves, fair value adjustment	128
Distribution relationships
Assets Acquired
Intangible assets	$ 220
Useful life	10 years
Value of business acquired
Assets Acquired
Intangible assets	$ 163
Other intangible assets
Assets Acquired
Intangible assets	$ 178	[1]
Minimum | Value of business acquired
Assets Acquired
Useful life	1 year
Minimum | Other intangible assets
Assets Acquired
Useful life	5 years
Maximum | Value of business acquired
Assets Acquired
Useful life	2 years
Maximum | Other intangible assets
Assets Acquired
Useful life	7 years

[1] Includes $128 million related to the net fair value adjustment to reserves for loss and loss adjustment expenses on August 1, 2024.