Investments (Details 3) $ in Millions	Jun. 30, 2015 USD ($) Holdings	Dec. 31, 2014 USD ($) Holdings
Indemnity
Fair value
Less than 12 months	$ 214	$ 202
12 months or longer	16	15
Total	230	217
Unrealized losses
Less than 12 months	3	4
12 months or longer	1	0
Total	$ 4	$ 4
No. of holdings | Holdings	296	295
Indemnity | Investment grade
Fair value
Less than 12 months	$ 153	$ 146
12 months or longer	0	2
Total	153	148
Unrealized losses
Less than 12 months	1	1
12 months or longer	0	0
Total	$ 1	$ 1
No. of holdings | Holdings	71	58
Indemnity | Non-investment grade
Fair value
Less than 12 months	$ 45	$ 56
12 months or longer	16	0
Total	61	56
Unrealized losses
Less than 12 months	1	3
12 months or longer	1	0
Total	$ 2	$ 3
No. of holdings | Holdings	222	236
Indemnity | Fixed maturities
Fair value
Less than 12 months	$ 198	$ 202
12 months or longer	16	2
Total	214	204
Unrealized losses
Less than 12 months	2	4
12 months or longer	1	0
Total	$ 3	$ 4
No. of holdings | Holdings	293	294
Indemnity | States & political subdivisions
Fair value
Less than 12 months	$ 17	$ 6
12 months or longer	0	2
Total	17	8
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	8	4
Indemnity | Corporate debt securities
Fair value
Less than 12 months	$ 123	$ 121
12 months or longer	16	0
Total	139	121
Unrealized losses
Less than 12 months	1	3
12 months or longer	1	0
Total	$ 2	$ 3
No. of holdings | Holdings	248	250
Indemnity | Residential mortgage-backed securities
Fair value
Less than 12 months	$ 4	$ 6
12 months or longer	0	0
Total	4	6
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	4	4
Indemnity | Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 35	$ 41
12 months or longer	0	0
Total	35	41
Unrealized losses
Less than 12 months	1	1
12 months or longer	0	0
Total	$ 1	$ 1
No. of holdings | Holdings	23	24
Indemnity | Collateralized debt obligations
Fair value
Less than 12 months	$ 16	$ 21
12 months or longer	0	0
Total	16	21
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	8	9
Indemnity | Other debt securities
Fair value
Less than 12 months	$ 3	$ 7
12 months or longer	0	0
Total	3	7
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	2	3
Indemnity | Nonredeemable preferred stock
Fair value
Less than 12 months	$ 4
12 months or longer	0
Total	4
Unrealized losses
Less than 12 months	0
12 months or longer	0
Total	$ 0
No. of holdings | Holdings	2
Indemnity | Common stock
Fair value
Less than 12 months	$ 12	$ 0
12 months or longer	0	13
Total	12	13
Unrealized losses
Less than 12 months	1	0
12 months or longer	0	0
Total	$ 1	$ 0
No. of holdings | Holdings	1	1
Exchange
Fair value
Less than 12 months	$ 2,492	$ 1,134
12 months or longer	152	360
Total	2,644	1,494
Unrealized losses
Less than 12 months	62	32
12 months or longer	9	9
Total	$ 71	$ 41
No. of holdings | Holdings	990	713
Exchange | Investment grade
Fair value
Less than 12 months	$ 1,893	$ 606
12 months or longer	66	253
Total	1,959	859
Unrealized losses
Less than 12 months	45	10
12 months or longer	2	5
Total	$ 47	$ 15
No. of holdings | Holdings	487	172
Exchange | Non-investment grade
Fair value
Less than 12 months	$ 446	$ 442
12 months or longer	64	9
Total	510	451
Unrealized losses
Less than 12 months	14	19
12 months or longer	6	2
Total	$ 20	$ 21
No. of holdings | Holdings	477	523
Exchange | Fixed maturities
Fair value
Less than 12 months	$ 2,339	$ 1,048
12 months or longer	130	262
Total	2,469	1,310
Unrealized losses
Less than 12 months	59	29
12 months or longer	8	7
Total	$ 67	$ 36
No. of holdings | Holdings	964	695
Exchange | U.S. treasury
Fair value
Less than 12 months	$ 2	$ 1
12 months or longer	0	0
Total	2	1
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	4	2
Exchange | States & political subdivisions
Fair value
Less than 12 months	$ 202	$ 47
12 months or longer	12	47
Total	214	94
Unrealized losses
Less than 12 months	2	0
12 months or longer	0	1
Total	$ 2	$ 1
No. of holdings | Holdings	59	24
Exchange | Foreign government securities
Fair value
Less than 12 months	$ 56
12 months or longer	0
Total	56
Unrealized losses
Less than 12 months	2
12 months or longer	0
Total	$ 2
No. of holdings | Holdings	34
Exchange | Corporate debt securities
Fair value
Less than 12 months	$ 2,042	$ 980
12 months or longer	100	181
Total	2,142	1,161
Unrealized losses
Less than 12 months	55	29
12 months or longer	7	5
Total	$ 62	$ 34
No. of holdings | Holdings	855	656
Exchange | Residential mortgage-backed securities
Fair value
Less than 12 months	$ 4	$ 6
12 months or longer	10	27
Total	14	33
Unrealized losses
Less than 12 months	0	0
12 months or longer	1	1
Total	$ 1	$ 1
No. of holdings | Holdings	4	8
Exchange | Commercial mortgage-backed securities
Fair value
Less than 12 months	$ 0	$ 1
12 months or longer	1	0
Total	1	1
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	1	1
Exchange | Other debt securities
Fair value
Less than 12 months	$ 33	$ 13
12 months or longer	7	7
Total	40	20
Unrealized losses
Less than 12 months	0	0
12 months or longer	0	0
Total	$ 0	$ 0
No. of holdings | Holdings	7	4
Exchange | Nonredeemable preferred stock
Fair value
Less than 12 months	$ 122	$ 86
12 months or longer	22	25
Total	144	111
Unrealized losses
Less than 12 months	2	3
12 months or longer	1	1
Total	$ 3	$ 4
No. of holdings | Holdings	25	16
Exchange | Common stock
Fair value
Less than 12 months	$ 31	$ 0
12 months or longer	0	73
Total	31	73
Unrealized losses
Less than 12 months	1	0
12 months or longer	0	1
Total	$ 1	$ 1
No. of holdings | Holdings	1	2