Investments (Net realized investment gains (losses)) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Net realized investment gains (losses)	$ 31	$ 63	$ (2)
Fixed maturity securities [Member]
Gross realized gains	201	232	289
Gross realized losses	(146)	(149)	(311)
Net realized investment gains (losses)	55	83	(22)
Equity securities [Member]
Gross realized gains	13	19	10
Gross realized losses	(35)	(42)	(11)
Net realized investment gains (losses)	(22)	(23)	(1)
Derivative [Member]
Net realized investment gains (losses)	(9)	(2)
Short term investments and other [Member]
Net realized investment gains (losses)	$ 7	$ 5	$ 21