Business Segments (Income Statement Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues
Net earned premiums	$ 1,735	$ 1,811	$ 3,422	$ 3,617
Net investment income	500	550	1,058	1,076
Other revenues	92	93	189	178
Total operating revenues	2,327	2,454	4,669	4,871
Claims, Benefits and Expenses
Net incurred claims and benefits	1,466	1,437	2,801	2,880
Policyholders' dividends	3	4	7	7
Amortization of deferred acquisition costs	314	335	617	664
Other insurance related expenses	259	259	527	521
Other expenses	121	41	250	169
Total claims, benefits and expenses	2,163	2,076	4,202	4,241
Operating income (loss) before income tax	164	378	467	630
Income tax (expense) benefit on operating income (loss)	(32)	(106)	(110)	(168)
Net operating income (loss)	132	272	357	462
Net realized investment gains (losses), pre-tax	0	(14)	10	32
Income tax (expense) benefit on net realized investment gains (losses)	6	3	4	(13)
Net realized investment gains (losses), after tax	6	(11)	14	19
Net income (loss) from continuing operations	138	261	371	481
Specialty [Member]
Operating Revenues
Net earned premiums	689	709	1,369	1,401
Net investment income	134	153	289	297
Other revenues	81	74	159	142
Total operating revenues	904	936	1,817	1,840
Claims, Benefits and Expenses
Net incurred claims and benefits	416	404	845	846
Policyholders' dividends	1	1	2	2
Amortization of deferred acquisition costs	146	148	290	291
Other insurance related expenses	66	67	135	132
Other expenses	69	65	136	126
Total claims, benefits and expenses	698	685	1,408	1,397
Operating income (loss) before income tax	206	251	409	443
Income tax (expense) benefit on operating income (loss)	(69)	(84)	(137)	(147)
Net operating income (loss)	137	167	272	296
Net realized investment gains (losses), pre-tax	0	(5)	4	6
Income tax (expense) benefit on net realized investment gains (losses)	0	1	(1)	(2)
Net realized investment gains (losses), after tax	0	(4)	3	4
Net income (loss) from continuing operations	137	163	275	300
Commercial [Member]
Operating Revenues
Net earned premiums	703	732	1,381	1,467
Net investment income	169	201	373	392
Other revenues	9	8	18	18
Total operating revenues	881	941	1,772	1,877
Claims, Benefits and Expenses
Net incurred claims and benefits	507	610	961	1,178
Policyholders' dividends	2	3	5	5
Amortization of deferred acquisition costs	117	126	234	249
Other insurance related expenses	130	125	257	251
Other expenses	5	7	13	15
Total claims, benefits and expenses	761	871	1,470	1,698
Operating income (loss) before income tax	120	70	302	179
Income tax (expense) benefit on operating income (loss)	(42)	(21)	(104)	(56)
Net operating income (loss)	78	49	198	123
Net realized investment gains (losses), pre-tax	2	(5)	6	5
Income tax (expense) benefit on net realized investment gains (losses)	2	(2)	(1)	(4)
Net realized investment gains (losses), after tax	4	(7)	5	1
Net income (loss) from continuing operations	82	42	203	124
International [Member]
Operating Revenues
Net earned premiums	207	231	398	472
Net investment income	13	16	27	31
Other revenues	(1)	0	(1)	0
Total operating revenues	219	247	424	503
Claims, Benefits and Expenses
Net incurred claims and benefits	114	118	230	248
Policyholders' dividends	0	0	0	0
Amortization of deferred acquisition costs	45	54	80	109
Other insurance related expenses	31	36	68	76
Other expenses	(5)	5	0	12
Total claims, benefits and expenses	185	213	378	445
Operating income (loss) before income tax	34	34	46	58
Income tax (expense) benefit on operating income (loss)	(12)	(14)	(15)	(22)
Net operating income (loss)	22	20	31	36
Net realized investment gains (losses), pre-tax	1	(3)	2	0
Income tax (expense) benefit on net realized investment gains (losses)	(1)	4	(1)	1
Net realized investment gains (losses), after tax	0	1	1	1
Net income (loss) from continuing operations	22	21	32	37
Life and Group Non-Core [Member]
Operating Revenues
Net earned premiums	137	139	275	278
Net investment income	179	173	358	344
Other revenues	0	8	9	13
Total operating revenues	316	320	642	635
Claims, Benefits and Expenses
Net incurred claims and benefits	344	304	684	610
Policyholders' dividends	0	0	0	0
Amortization of deferred acquisition costs	6	7	13	15
Other insurance related expenses	34	31	69	63
Other expenses	5	(3)	9	(2)
Total claims, benefits and expenses	389	339	775	686
Operating income (loss) before income tax	(73)	(19)	(133)	(51)
Income tax (expense) benefit on operating income (loss)	49	28	92	58
Net operating income (loss)	(24)	9	(41)	7
Net realized investment gains (losses), pre-tax	(5)	(4)	(4)	12
Income tax (expense) benefit on net realized investment gains (losses)	6	1	8	(5)
Net realized investment gains (losses), after tax	1	(3)	4	7
Net income (loss) from continuing operations	(23)	6	(37)	14
Corporate and Other Non-Core [Member]
Operating Revenues
Net earned premiums	0	0	0	0
Net investment income	5	7	11	12
Other revenues	3	5	5	7
Total operating revenues	8	12	16	19
Claims, Benefits and Expenses
Net incurred claims and benefits	85	1	81	(2)
Policyholders' dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	(1)	0	(1)	0
Other expenses	47	(31)	93	20
Total claims, benefits and expenses	131	(30)	173	18
Operating income (loss) before income tax	(123)	42	(157)	1
Income tax (expense) benefit on operating income (loss)	42	(15)	54	(1)
Net operating income (loss)	(81)	27	(103)	0
Net realized investment gains (losses), pre-tax	2	3	2	9
Income tax (expense) benefit on net realized investment gains (losses)	(1)	(1)	(1)	(3)
Net realized investment gains (losses), after tax	1	2	1	6
Net income (loss) from continuing operations	(80)	29	(102)	6
Eliminations [Member]
Operating Revenues
Net earned premiums	(1)	0	(1)	(1)
Net investment income	0	0	0	0
Other revenues	0	(2)	(1)	(2)
Total operating revenues	(1)	(2)	(2)	(3)
Claims, Benefits and Expenses
Net incurred claims and benefits	0	0	0	0
Policyholders' dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Other insurance related expenses	(1)	0	(1)	(1)
Other expenses	0	(2)	(1)	(2)
Total claims, benefits and expenses	(1)	(2)	(2)	(3)
Operating income (loss) before income tax	0	0	0	0
Income tax (expense) benefit on operating income (loss)	0	0	0	0
Net operating income (loss)	0	0	0	0
Net realized investment gains (losses), pre-tax	0	0	0	0
Income tax (expense) benefit on net realized investment gains (losses)	0	0	0	0
Net realized investment gains (losses), after tax	0	0	0	0
Net income (loss) from continuing operations	$ 0	$ 0	$ 0	$ 0