Benefit Plans - Allstate 401(k) Savings Plan (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Company's contribution to the Allstate plan	$ 126	$ 124	$ 131
Defined contribution plan expense for eligible employees of canadian insurance subsidiaries and Sterling	$ 14	$ 14	$ 9