Investments (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Investment income from portfolios
Investment income, net of expenses	$ 109	$ 103
Indemnity
Investment income from portfolios
Total investment income	4	4
Less: investment expenses	0	0
Investment income, net of expenses	4	4
Indemnity | Fixed maturities
Investment income from portfolios
Total investment income	3	3
Indemnity | Equity securities
Investment income from portfolios
Total investment income	1	1
Indemnity | Cash equivalents and other
Investment income from portfolios
Total investment income	0	0
Exchange
Investment income from portfolios
Total investment income	115	107
Less: investment expenses	10	8
Investment income, net of expenses	105	99
Exchange | Fixed maturities
Investment income from portfolios
Total investment income	86	83
Exchange | Equity securities
Investment income from portfolios
Total investment income	29	24
Exchange | Cash equivalents and other
Investment income from portfolios
Total investment income	$ 0	$ 0