Investments (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014 Holdings	Dec. 31, 2013 Holdings
Indemnity
Fair value
Less than 12 months	$ 202	$ 129
12 months or longer	15	26
Total	217	155
Unrealized losses
Less than 12 months	4	3
12 months or longer	0	0
Total	4	3
No. of holdings	295	38
Indemnity | Investment grade
Fair value
Less than 12 months	146	112
12 months or longer	2	10
Total	148	122
Unrealized losses
Less than 12 months	1	1
12 months or longer	0	0
Total	1	1
No. of holdings	58	32
Indemnity | Non-investment grade
Fair value
Less than 12 months	56	0
12 months or longer	0	0
Total	56	0
Unrealized losses
Less than 12 months	3	0
12 months or longer	0	0
Total	3	0
No. of holdings	236	0
Indemnity | Fixed maturities
Fair value
Less than 12 months	202	112
12 months or longer	2	10
Total	204	122
Unrealized losses
Less than 12 months	4	1
12 months or longer	0	0
Total	4	1
No. of holdings	294	32
Indemnity | States & political subdivisions
Fair value
Less than 12 months	6	58
12 months or longer	2	0
Total	8	58
Unrealized losses
Less than 12 months	0	1
12 months or longer	0	0
Total	0	1
No. of holdings	4	21
Indemnity | Corporate debt securities
Fair value
Less than 12 months	121	54
12 months or longer	0	10
Total	121	64
Unrealized losses
Less than 12 months	3	0
12 months or longer	0	0
Total	3	0
No. of holdings	250	11
Indemnity | Residential mortgage-backed securities
Fair value
Less than 12 months	6
12 months or longer	0
Total	6
Unrealized losses
Less than 12 months	0
12 months or longer	0
Total	0
No. of holdings	4
Indemnity | Commercial mortgage-backed securities
Fair value
Less than 12 months	41
12 months or longer	0
Total	41
Unrealized losses
Less than 12 months	1
12 months or longer	0
Total	1
No. of holdings	24
Indemnity | Collateralized debt obligations
Fair value
Less than 12 months	21
12 months or longer	0
Total	21
Unrealized losses
Less than 12 months	0
12 months or longer	0
Total	0
No. of holdings	9
Indemnity | Other debt securities
Fair value
Less than 12 months	7
12 months or longer	0
Total	7
Unrealized losses
Less than 12 months	0
12 months or longer	0
Total	0
No. of holdings	3
Indemnity | Nonredeemable preferred stock
Fair value
Less than 12 months		5
12 months or longer		3
Total		8
Unrealized losses
Less than 12 months		1
12 months or longer		0
Total		1
No. of holdings		4
Indemnity | Common stock
Fair value
Less than 12 months	0	12
12 months or longer	13	13
Total	13	25
Unrealized losses
Less than 12 months	0	1
12 months or longer	0	0
Total	0	1
No. of holdings	1	2
Exchange
Fair value
Less than 12 months	1,134	2,050
12 months or longer	360	176
Total	1,494	2,226
Unrealized losses
Less than 12 months	32	74
12 months or longer	9	5
Total	41	79
No. of holdings	713	388
Exchange | Investment grade
Fair value
Less than 12 months	606	1,707
12 months or longer	253	62
Total	859	1,769
Unrealized losses
Less than 12 months	10	57
12 months or longer	5	4
Total	15	61
No. of holdings	172	344
Exchange | Non-investment grade
Fair value
Less than 12 months	442	64
12 months or longer	9	0
Total	451	64
Unrealized losses
Less than 12 months	19	4
12 months or longer	2	0
Total	21	4
No. of holdings	523	14
Exchange | Fixed maturities
Fair value
Less than 12 months	1,048	1,771
12 months or longer	262	62
Total	1,310	1,833
Unrealized losses
Less than 12 months	29	61
12 months or longer	7	4
Total	36	65
No. of holdings	695	358
Exchange | U.S. government & agencies
Fair value
Less than 12 months		1
12 months or longer		0
Total		1
Unrealized losses
Less than 12 months		0
12 months or longer		0
Total		0
No. of holdings		2
Exchange | U.S. treasury
Fair value
Less than 12 months	1
12 months or longer	0
Total	1
Unrealized losses
Less than 12 months	0
12 months or longer	0
Total	0
No. of holdings	2
Exchange | States & political subdivisions
Fair value
Less than 12 months	47	408
12 months or longer	47	18
Total	94	426
Unrealized losses
Less than 12 months	0	13
12 months or longer	1	2
Total	1	15
No. of holdings	24	100
Exchange | Foreign government securities
Fair value
Less than 12 months		5
12 months or longer		0
Total		5
Unrealized losses
Less than 12 months		0
12 months or longer		0
Total		0
No. of holdings		1
Exchange | Corporate debt securities
Fair value
Less than 12 months	980	1,251
12 months or longer	181	36
Total	1,161	1,287
Unrealized losses
Less than 12 months	29	43
12 months or longer	5	2
Total	34	45
No. of holdings	656	237
Exchange | Residential mortgage-backed securities
Fair value
Less than 12 months	6	71
12 months or longer	27	8
Total	33	79
Unrealized losses
Less than 12 months	0	4
12 months or longer	1	0
Total	1	4
No. of holdings	8	12
Exchange | Commercial mortgage-backed securities
Fair value
Less than 12 months	1	5
12 months or longer	0	0
Total	1	5
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	0	0
No. of holdings	1	1
Exchange | Other debt securities
Fair value
Less than 12 months	13	30
12 months or longer	7	0
Total	20	30
Unrealized losses
Less than 12 months	0	1
12 months or longer	0	0
Total	0	1
No. of holdings	4	5
Exchange | Nonredeemable preferred stock
Fair value
Less than 12 months	86	182
12 months or longer	25	13
Total	111	195
Unrealized losses
Less than 12 months	3	10
12 months or longer	1	1
Total	4	11
No. of holdings	16	27
Exchange | Common stock
Fair value
Less than 12 months	0	97
12 months or longer	73	101
Total	73	198
Unrealized losses
Less than 12 months	0	3
12 months or longer	1	0
Total	$ 1	$ 3
No. of holdings	2	3