Assets and Liabilities Held For Sale - Narrative (Details) - Disposal Group, Held-for-sale, Not Discontinued Operations - Brokerage Insurance - USD ($) $ in Millions		3 Months Ended	9 Months Ended
May 26, 2021	Sep. 30, 2021	Sep. 30, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses	$ 500
Impairment charge		$ 0	$ 0

Amount, before tax, of (gain) loss recognized for the (reversal of write-down) write-down to fair value, less cost to sell, of a disposal group. Excludes discontinued operations.

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