Reporting Segments (Details 5) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information
Assets	$ 126,947	$ 125,193	$ 130,500
Investments	97,278	95,618	100,483
Property-Liability
Segment Reporting Information
Assets	52,201	49,791	47,536
Investments	38,215	35,998	35,048
Allstate Financial
Segment Reporting Information
Assets	72,368	72,526	78,732
Investments	56,999	57,373	61,582
Corporate and Other
Segment Reporting Information
Assets	2,378	2,876	4,232
Investments	$ 2,064	$ 2,247	$ 3,853