Investments (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investment income from portfolios
Investment income, net of expenses	$ 115	$ 109	$ 335	$ 316
Indemnity
Investment income from portfolios
Total investment income	4	4	12	12
Less: investment expenses	0	0	0	1
Investment income, net of expenses	4	4	12	11
Indemnity | Fixed maturities
Investment income from portfolios
Total investment income	4	3	10	9
Indemnity | Equity securities
Investment income from portfolios
Total investment income	0	1	1	2
Indemnity | Cash equivalents and other
Investment income from portfolios
Total investment income	0	0	1	1
Exchange
Investment income from portfolios
Total investment income	120	113	351	330
Less: investment expenses	9	8	28	25
Investment income, net of expenses	111	105	323	305
Exchange | Fixed maturities
Investment income from portfolios
Total investment income	90	83	261	249
Exchange | Equity securities
Investment income from portfolios
Total investment income	30	29	89	80
Exchange | Cash equivalents and other
Investment income from portfolios
Total investment income	$ 0	$ 1	$ 1	$ 1