Business Segments (Income statement information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating revenues
Net earned premiums	$ 2,155	$ 2,035	$ 4,214	$ 3,997
Net investment income	432	591	880	1,095
Non-insurance warranty revenue	392	359	774	697
Other revenues	6	6	13	11
Total operating revenues	2,985	2,991	5,881	5,800
Claims, Benefits and Expenses
Net incurred claims and benefits	1,576	1,539	3,025	3,039
Policyholders’ dividends	7	7	13	13
Amortization of deferred acquisition costs	374	357	718	716
Non-insurance warranty expense	367	332	721	643
Other insurance related expenses	275	271	566	526
Other expenses	82	61	145	118
Total claims, benefits and expenses	2,681	2,567	5,188	5,055
Core income (loss) before income tax	304	424	693	745
Income tax (expense) benefit on core income (loss)	(59)	(83)	(132)	(141)
Core income (loss)	245	341	561	604
Net investment gains (losses)	(59)	38	(70)	95
Income tax (expense) benefit on net investment gains (losses)	19	(11)	27	(19)
Net investment gains (losses), after tax	(40)	27	(43)	76
Net income (loss)	205	368	518	680
Operating Segments | Specialty
Operating revenues
Net earned premiums	794	762	1,566	1,497
Net investment income	100	134	203	251
Non-insurance warranty revenue	392	359	774	697
Other revenues	0	0	1	0
Total operating revenues	1,286	1,255	2,544	2,445
Claims, Benefits and Expenses
Net incurred claims and benefits	456	439	901	866
Policyholders’ dividends	2	1	3	2
Amortization of deferred acquisition costs	162	159	319	313
Non-insurance warranty expense	367	332	721	643
Other insurance related expenses	81	71	162	141
Other expenses	12	12	25	23
Total claims, benefits and expenses	1,080	1,014	2,131	1,988
Core income (loss) before income tax	206	241	413	457
Income tax (expense) benefit on core income (loss)	(45)	(53)	(89)	(99)
Core income (loss)	161	188	324	358
Operating Segments | Commercial
Operating revenues
Net earned premiums	974	881	1,878	1,736
Net investment income	113	174	231	322
Non-insurance warranty revenue	0	0	0	0
Other revenues	4	5	12	10
Total operating revenues	1,091	1,060	2,121	2,068
Claims, Benefits and Expenses
Net incurred claims and benefits	610	588	1,183	1,227
Policyholders’ dividends	5	6	10	11
Amortization of deferred acquisition costs	156	148	304	301
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	134	136	264	251
Other expenses	11	11	18	20
Total claims, benefits and expenses	916	889	1,779	1,810
Core income (loss) before income tax	175	171	342	258
Income tax (expense) benefit on core income (loss)	(37)	(34)	(72)	(52)
Core income (loss)	138	137	270	206
Operating Segments | International
Operating revenues
Net earned premiums	269	266	533	518
Net investment income	14	14	28	28
Non-insurance warranty revenue	0	0	0	0
Other revenues	1	1	0	1
Total operating revenues	284	281	561	547
Claims, Benefits and Expenses
Net incurred claims and benefits	160	159	318	314
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	56	50	95	102
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	30	39	77	74
Other expenses	13	(3)	14	(8)
Total claims, benefits and expenses	259	245	504	482
Core income (loss) before income tax	25	36	57	65
Income tax (expense) benefit on core income (loss)	(7)	(10)	(13)	(15)
Core income (loss)	18	26	44	50
Operating Segments | Life & Group
Operating revenues
Net earned premiums	118	126	238	246
Net investment income	201	265	413	484
Non-insurance warranty revenue	0	0	0	0
Other revenues	1	(1)	0	0
Total operating revenues	320	390	651	730
Claims, Benefits and Expenses
Net incurred claims and benefits	293	322	574	603
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	29	25	60	50
Other expenses	2	2	5	4
Total claims, benefits and expenses	324	349	639	657
Core income (loss) before income tax	(4)	41	12	73
Income tax (expense) benefit on core income (loss)	10	2	17	6
Core income (loss)	6	43	29	79
Operating Segments | Corporate & Other
Operating revenues
Net earned premiums	0	0	(1)	0
Net investment income	4	4	5	10
Non-insurance warranty revenue	0	0	0	0
Other revenues	1	2	3	3
Total operating revenues	5	6	7	13
Claims, Benefits and Expenses
Net incurred claims and benefits	57	31	49	29
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	1	0	3	10
Other expenses	45	40	86	82
Total claims, benefits and expenses	103	71	138	121
Core income (loss) before income tax	(98)	(65)	(131)	(108)
Income tax (expense) benefit on core income (loss)	20	12	25	19
Core income (loss)	(78)	(53)	(106)	(89)
Eliminations
Operating revenues
Net earned premiums	0	0	0	0
Net investment income	0	0	0	0
Non-insurance warranty revenue	0	0	0	0
Other revenues	(1)	(1)	(3)	(3)
Total operating revenues	(1)	(1)	(3)	(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
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	0	0	0	0
Other expenses	(1)	(1)	(3)	(3)
Total claims, benefits and expenses	(1)	(1)	(3)	(3)
Core income (loss) before income tax	0	0	0	0
Income tax (expense) benefit on core income (loss)	0	0	0	0
Core income (loss)	$ 0	$ 0	$ 0	$ 0