Segments of Operations (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets:
Total assets	$ 36,042	$ 32,454	$ 27,683
Property and Casualty Insurance [Member]
Assets:
Total assets	11,882	11,609	11,863
Annuity and Supplemental Insurance [Member]
Assets:
Total assets	20,451	17,766	15,476
Other Segment [Member]
Assets:
Total assets	$ 3,709	$ 3,079	$ 344