Statutory Financial Information and Dividend Limitations - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Dividend Limitations
Action level RBC expressed as a multiplier of authorized control level RBC, which if not achieved would require specific actions to be taken	2
Capital and surplus	$ 18,630	$ 16,819
Restricted net assets	26,000
Allstate Insurance Company
Dividend Limitations
Dividends paid	1,560
Maximum amount of dividends without prior approval	$ 2,870
Advance notice period required for payment of dividend in excess of amount available for distribution without prior approval	30 days
Unassigned surplus excluding unrealized appreciation from investments	$ 11,040
Capital and surplus	17,700
Authorized control level RBC	$ 2,800