Reinsurance (Components of Life Insurance Inforce) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Life Insurance Inforce, Direct	$ 5,713	$ 6,528	$ 8,015
Life Insurance Inforce, Assumed
Life Insurance Inforce, Ceded	5,702	6,515	8,001
Life Insurance Inforce, Net	$ 11	$ 13	$ 14