(Details)	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 410,000,000	$ 279,000,000	$ 192,000,000
Statutory capital and surplus	3,470,000,000	3,410,000,000
Dividends paid	250,000,000	600,000,000	$ 0
Maximum amount of dividends ALIC able to pay without prior IL DOI approval	347,000,000
Deficit position used to determine payment of dividends	$ 323,000,000
Multiplier of authorized control level RBC to determine action level RBC	2
Statutory accounting practices, statutory capital and surplus, adjusted balance	$ 3,900,000,000
Authorized control level RBC	680,000,000
Subsidiaries | Allstate Life Insurance Company
Statutory Accounting Practices [Line Items]
Dividends paid	0	$ 0
Maximum amount of dividends ALIC able to pay without prior IL DOI approval	$ 64,000,000