Statutory Financial Information and Dividend Limitations - Allstates domestic insurance subsidiaries (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amount per statutory accounting practices
Net income (loss)	$ 4,411	$ 3,404	$ 3,377
Capital and surplus	20,400	18,147
Property-Liability
Amount per statutory accounting practices
Net income (loss)	3,989	2,939	3,050
Capital and surplus	16,192	14,328
Allstate Annuities
Amount per statutory accounting practices
Net income (loss)	422	465	$ 327
Capital and surplus	$ 4,208	$ 3,819