Business Segments (Income Statement Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Operating Revenues
Net earned premiums	$ 1,687	$ 1,806
Net investment income	558	526
Other revenues	97	85
Total operating revenues	2,342	2,417
Claims, Benefits and Expenses
Net incurred claims and benefits	1,335	1,443
Policyholders' dividends	4	3
Amortization of deferred acquisition costs	303	329
Other insurance related expenses	268	262
Other expenses	129	128
Total claims, benefits and expenses	2,039	2,165
Operating income (loss) before income tax	303	252
Income tax (expense) benefit on operating income (loss)	(78)	(62)
Net operating income (loss)	225	190
Net realized investment gains (losses), pre-tax	10	46
Income tax (expense) benefit on net realized investment gains (losses)	(2)	(16)
Net realized investment gains (losses), after tax	8	30
Net income (loss) from continuing operations	233	220
Specialty [Member]
Operating Revenues
Net earned premiums	680	692
Net investment income	155	144
Other revenues	78	68
Total operating revenues	913	904
Claims, Benefits and Expenses
Net incurred claims and benefits	429	442
Policyholders' dividends	1	1
Amortization of deferred acquisition costs	144	143
Other insurance related expenses	69	65
Other expenses	67	61
Total claims, benefits and expenses	710	712
Operating income (loss) before income tax	203	192
Income tax (expense) benefit on operating income (loss)	(68)	(63)
Net operating income (loss)	135	129
Net realized investment gains (losses), pre-tax	4	11
Income tax (expense) benefit on net realized investment gains (losses)	(1)	(3)
Net realized investment gains (losses), after tax	3	8
Net income (loss) from continuing operations	138	137
Commercial [Member]
Operating Revenues
Net earned premiums	678	735
Net investment income	204	191
Other revenues	9	10
Total operating revenues	891	936
Claims, Benefits and Expenses
Net incurred claims and benefits	454	568
Policyholders' dividends	3	2
Amortization of deferred acquisition costs	117	123
Other insurance related expenses	127	126
Other expenses	8	8
Total claims, benefits and expenses	709	827
Operating income (loss) before income tax	182	109
Income tax (expense) benefit on operating income (loss)	(62)	(35)
Net operating income (loss)	120	74
Net realized investment gains (losses), pre-tax	4	10
Income tax (expense) benefit on net realized investment gains (losses)	(3)	(2)
Net realized investment gains (losses), after tax	1	8
Net income (loss) from continuing operations	121	82
International [Member]
Operating Revenues
Net earned premiums	191	241
Net investment income	14	15
Other revenues	0	0
Total operating revenues	205	256
Claims, Benefits and Expenses
Net incurred claims and benefits	116	130
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	35	55
Other insurance related expenses	37	40
Other expenses	5	7
Total claims, benefits and expenses	193	232
Operating income (loss) before income tax	12	24
Income tax (expense) benefit on operating income (loss)	(3)	(8)
Net operating income (loss)	9	16
Net realized investment gains (losses), pre-tax	1	3
Income tax (expense) benefit on net realized investment gains (losses)	0	(3)
Net realized investment gains (losses), after tax	1	0
Net income (loss) from continuing operations	10	16
Life and Group Non-Core [Member]
Operating Revenues
Net earned premiums	138	139
Net investment income	179	171
Other revenues	9	5
Total operating revenues	326	315
Claims, Benefits and Expenses
Net incurred claims and benefits	340	306
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	7	8
Other insurance related expenses	35	32
Other expenses	4	1
Total claims, benefits and expenses	386	347
Operating income (loss) before income tax	(60)	(32)
Income tax (expense) benefit on operating income (loss)	43	30
Net operating income (loss)	(17)	(2)
Net realized investment gains (losses), pre-tax	1	16
Income tax (expense) benefit on net realized investment gains (losses)	2	(6)
Net realized investment gains (losses), after tax	3	10
Net income (loss) from continuing operations	(14)	8
Corporate and Other Non-Core [Member]
Operating Revenues
Net earned premiums	0	0
Net investment income	6	5
Other revenues	2	2
Total operating revenues	8	7
Claims, Benefits and Expenses
Net incurred claims and benefits	(4)	(3)
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	0	0
Other insurance related expenses	0	0
Other expenses	46	51
Total claims, benefits and expenses	42	48
Operating income (loss) before income tax	(34)	(41)
Income tax (expense) benefit on operating income (loss)	12	14
Net operating income (loss)	(22)	(27)
Net realized investment gains (losses), pre-tax	0	6
Income tax (expense) benefit on net realized investment gains (losses)	0	(2)
Net realized investment gains (losses), after tax	0	4
Net income (loss) from continuing operations	(22)	(23)
Eliminations [Member]
Operating Revenues
Net earned premiums	0	(1)
Net investment income	0	0
Other revenues	(1)	0
Total operating revenues	(1)	(1)
Claims, Benefits and Expenses
Net incurred claims and benefits	0	0
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	0	0
Other insurance related expenses	0	(1)
Other expenses	(1)	0
Total claims, benefits and expenses	(1)	(1)
Operating income (loss) before income tax	0	0
Income tax (expense) benefit on operating income (loss)	0	0
Net operating income (loss)	0	0
Net realized investment gains (losses), pre-tax	0	0
Income tax (expense) benefit on net realized investment gains (losses)	0	0
Net realized investment gains (losses), after tax	0	0
Net income (loss) from continuing operations	$ 0	$ 0