Reporting Segments (Details 4) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information
Assets	$ 125,563	$ 130,874	$ 132,652
Investments	95,618	100,483	99,833
Property-Liability
Segment Reporting Information
Assets	49,833	47,573	47,179
Investments	35,998	35,048	34,526
Allstate Financial
Segment Reporting Information
Assets	72,854	79,069	81,968
Investments	57,373	61,582	62,216
Corporate and Other
Segment Reporting Information
Assets	2,876	4,232	3,505
Investments	$ 2,247	$ 3,853	$ 3,091