Business Segments (Income Statement Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Revenues
Net earned premiums	$ 1,699	$ 1,687
Net investment income	435	558
Other revenues	97	97
Total operating revenues	2,231	2,342
Claims, Benefits and Expenses
Net incurred claims and benefits	1,404	1,335
Policyholders' dividends	4	4
Amortization of deferred acquisition costs	307	303
Other insurance related expenses	277	268
Other expenses	146	129
Total claims, benefits and expenses	2,138	2,039
Operating income (loss) before income tax	93	303
Income tax (expense) benefit on operating income (loss)	(2)	(78)
Net operating income (loss)	91	225
Net realized investment gains (losses), pre-tax	(36)	10
Income tax (expense) benefit on net realized investment gains (losses)	11	(2)
Net realized investment gains (losses), after tax	(25)	8
Net Income (Loss)	66	233
Specialty [Member]
Operating Revenues
Net earned premiums	682	680
Net investment income	107	155
Other revenues	87	78
Total operating revenues	876	913
Claims, Benefits and Expenses
Net incurred claims and benefits	390	429
Policyholders' dividends	1	1
Amortization of deferred acquisition costs	144	144
Other insurance related expenses	75	69
Other expenses	75	67
Total claims, benefits and expenses	685	710
Operating income (loss) before income tax	191	203
Income tax (expense) benefit on operating income (loss)	(64)	(68)
Net operating income (loss)	127	135
Net realized investment gains (losses), pre-tax	(11)	4
Income tax (expense) benefit on net realized investment gains (losses)	4	(1)
Net realized investment gains (losses), after tax	(7)	3
Net Income (Loss)	120	138
Commercial [Member]
Operating Revenues
Net earned premiums	688	678
Net investment income	126	204
Other revenues	6	9
Total operating revenues	820	891
Claims, Benefits and Expenses
Net incurred claims and benefits	442	454
Policyholders' dividends	3	3
Amortization of deferred acquisition costs	116	117
Other insurance related expenses	141	127
Other expenses	5	8
Total claims, benefits and expenses	707	709
Operating income (loss) before income tax	113	182
Income tax (expense) benefit on operating income (loss)	(39)	(62)
Net operating income (loss)	74	120
Net realized investment gains (losses), pre-tax	(18)	4
Income tax (expense) benefit on net realized investment gains (losses)	6	(3)
Net realized investment gains (losses), after tax	(12)	1
Net Income (Loss)	62	121
International [Member]
Operating Revenues
Net earned premiums	198	191
Net investment income	12	14
Other revenues	1	0
Total operating revenues	211	205
Claims, Benefits and Expenses
Net incurred claims and benefits	121	116
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	47	35
Other insurance related expenses	28	37
Other expenses	9	5
Total claims, benefits and expenses	205	193
Operating income (loss) before income tax	6	12
Income tax (expense) benefit on operating income (loss)	0	(3)
Net operating income (loss)	6	9
Net realized investment gains (losses), pre-tax	4	1
Income tax (expense) benefit on net realized investment gains (losses)	(1)	0
Net realized investment gains (losses), after tax	3	1
Net Income (Loss)	9	10
Life and Group Non-Core [Member]
Operating Revenues
Net earned premiums	131	138
Net investment income	187	179
Other revenues	0	9
Total operating revenues	318	326
Claims, Benefits and Expenses
Net incurred claims and benefits	323	340
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	0	7
Other insurance related expenses	33	35
Other expenses	3	4
Total claims, benefits and expenses	359	386
Operating income (loss) before income tax	(41)	(60)
Income tax (expense) benefit on operating income (loss)	39	43
Net operating income (loss)	(2)	(17)
Net realized investment gains (losses), pre-tax	(3)	1
Income tax (expense) benefit on net realized investment gains (losses)	0	2
Net realized investment gains (losses), after tax	(3)	3
Net Income (Loss)	(5)	(14)
Corporate and Other Non-Core [Member]
Operating Revenues
Net earned premiums	0	0
Net investment income	3	6
Other revenues	3	2
Total operating revenues	6	8
Claims, Benefits and Expenses
Net incurred claims and benefits	128	(4)
Policyholders' dividends	0	0
Amortization of deferred acquisition costs	0	0
Other insurance related expenses	0	0
Other expenses	54	46
Total claims, benefits and expenses	182	42
Operating income (loss) before income tax	(176)	(34)
Income tax (expense) benefit on operating income (loss)	62	12
Net operating income (loss)	(114)	(22)
Net realized investment gains (losses), pre-tax	(8)	0
Income tax (expense) benefit on net realized investment gains (losses)	2	0
Net realized investment gains (losses), after tax	(6)	0
Net Income (Loss)	(120)	(22)
Eliminations [Member]
Operating Revenues
Net earned premiums	0	0
Net investment income	0	0
Other revenues	0	(1)
Total operating revenues	0	(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	0
Other expenses	0	(1)
Total claims, benefits and expenses	0	(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)	$ 0	$ 0