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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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The cash inflow associated with the deconsolidation of a previously consolidated subsidiary or the sale of investment in consolidated subsidiaries (generally greater than 50 percent).

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The cash outflow from the repayment of long-term borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in case of liquidation of the entity's assets or underlying collateral.

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Acquisitions and Dispositions - Narrative (Details) $ in Millions					9 Months Ended
	Nov. 01, 2021 USD ($)	Oct. 01, 2021 USD ($) state	Mar. 15, 2021 USD ($)	Feb. 03, 2021 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jan. 04, 2021 USD ($)
Business Acquisition [Line Items]
Goodwill					$ 3,502	$ 3,502
Long-term debt					$ 7,967	$ 7,976
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Allstate Life Insurance Company Of New York
Business Acquisition [Line Items]
Definitive agreement with Wilton Reassurance		$ 400
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Allstate Life Insurance Company
Business Acquisition [Line Items]
Proceeds from affiliates	$ 4,000
Pre-close dividend	$ 1,250
Subordinated Debt
Business Acquisition [Line Items]
Repaid of subordinated notes			$ 72	$ 100
Subsequent acquisition (in percentage)				7.625%
Senior Notes
Business Acquisition [Line Items]
Subsequent acquisition (in percentage)					6.75%
Long-term debt					$ 350
National General Holdings Corp.
Business Acquisition [Line Items]
Goodwill							$ 1,038
Purchase accounting fair value adjustment					$ 31
National General Holdings Corp. \| Allstate Protection
Business Acquisition [Line Items]
Goodwill							675
National General Holdings Corp. \| Protection Services
Business Acquisition [Line Items]
Goodwill							20
National General Holdings Corp. \| Allstate Health and Benefits
Business Acquisition [Line Items]
Goodwill							$ 343
SafeAuto
Business Acquisition [Line Items]
Number of states acquiree operates in \| state		28
Cash to acquire businesses		$ 267