Investments (details) - Impairment Charges (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Impairment charges
Impairment charges	$ 9	$ 5
Fixed maturities [Member]
Impairment charges
Impairment charges	3	1
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Impairment charges
Impairment charges		1
All other corporate bonds [Member]
Impairment charges
Impairment charges	3
Equity securities [Member]
Impairment charges
Impairment charges	5
Equity securities, common stock [Member]
Impairment charges
Impairment charges	5
Other investments [Member]
Impairment charges
Impairment charges	$ 1	$ 4