Business Segments (Income statement information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating revenues
Net earned premiums	$ 2,221	$ 2,059	$ 6,435	$ 6,056
Net investment income	422	513	1,302	1,608
Non-insurance warranty revenue	399	357	1,173	1,054
Other revenues	11	8	24	19
Total operating revenues	3,053	2,937	8,934	8,737
Claims, Benefits and Expenses
Net incurred claims and benefits	1,658	1,627	4,683	4,666
Policyholders’ dividends	7	5	20	18
Amortization of deferred acquisition costs	383	368	1,101	1,084
Non-insurance warranty expense	371	330	1,092	973
Other insurance related expenses	297	253	863	779
Other expenses	77	62	222	180
Total claims, benefits and expenses	2,793	2,645	7,981	7,700
Core income (loss) before income tax	260	292	953	1,037
Income tax (expense) benefit on core income (loss)	(47)	(55)	(179)	(196)
Core income (loss)	213	237	774	841
Net investment gains (losses)	(96)	22	(166)	117
Income tax (expense) benefit on net investment gains (losses)	11	(3)	38	(22)
Net investment gains (losses), after tax	(85)	19	(128)	95
Net income (loss)	128	256	646	936
Operating Segments | Specialty
Operating revenues
Net earned premiums	810	773	2,376	2,270
Net investment income	102	116	305	367
Non-insurance warranty revenue	399	357	1,173	1,054
Other revenues	(1)	1	0	1
Total operating revenues	1,310	1,247	3,854	3,692
Claims, Benefits and Expenses
Net incurred claims and benefits	459	446	1,360	1,312
Policyholders’ dividends	2	0	5	2
Amortization of deferred acquisition costs	169	165	488	478
Non-insurance warranty expense	371	330	1,092	973
Other insurance related expenses	88	71	250	212
Other expenses	15	13	40	36
Total claims, benefits and expenses	1,104	1,025	3,235	3,013
Core income (loss) before income tax	206	222	619	679
Income tax (expense) benefit on core income (loss)	(45)	(49)	(134)	(148)
Core income (loss)	161	173	485	531
Operating Segments | Commercial
Operating revenues
Net earned premiums	1,023	893	2,901	2,629
Net investment income	112	141	343	463
Non-insurance warranty revenue	0	0	0	0
Other revenues	13	7	25	17
Total operating revenues	1,148	1,041	3,269	3,109
Claims, Benefits and Expenses
Net incurred claims and benefits	733	720	1,916	1,947
Policyholders’ dividends	5	5	15	16
Amortization of deferred acquisition costs	163	148	467	449
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	145	125	409	376
Other expenses	3	8	21	28
Total claims, benefits and expenses	1,049	1,006	2,828	2,816
Core income (loss) before income tax	99	35	441	293
Income tax (expense) benefit on core income (loss)	(19)	(8)	(91)	(60)
Core income (loss)	80	27	350	233
Operating Segments | International
Operating revenues
Net earned premiums	270	271	803	789
Net investment income	16	14	44	42
Non-insurance warranty revenue	0	0	0	0
Other revenues	0	0	0	1
Total operating revenues	286	285	847	832
Claims, Benefits and Expenses
Net incurred claims and benefits	169	171	487	485
Policyholders’ dividends	0	0	0	0
Amortization of deferred acquisition costs	51	55	146	157
Non-insurance warranty expense	0	0	0	0
Other insurance related expenses	35	32	112	106
Other expenses	11	4	25	(4)
Total claims, benefits and expenses	266	262	770	744
Core income (loss) before income tax	20	23	77	88
Income tax (expense) benefit on core income (loss)	(1)	(6)	(14)	(21)
Core income (loss)	19	17	63	67
Operating Segments | Life & Group
Operating revenues
Net earned premiums	118	123	356	369
Net investment income	187	240	600	724
Non-insurance warranty revenue	0	0	0	0
Other revenues	0	(1)	0	(1)
Total operating revenues	305	362	956	1,092
Claims, Benefits and Expenses
Net incurred claims and benefits	310	296	884	899
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	27	89	77
Other expenses	2	1	7	5
Total claims, benefits and expenses	341	324	980	981
Core income (loss) before income tax	(36)	38	(24)	111
Income tax (expense) benefit on core income (loss)	14	3	31	9
Core income (loss)	(22)	41	7	120
Operating Segments | Corporate & Other
Operating revenues
Net earned premiums	0	0	(1)	0
Net investment income	5	2	10	12
Non-insurance warranty revenue	0	0	0	0
Other revenues	1	2	4	5
Total operating revenues	6	4	13	17
Claims, Benefits and Expenses
Net incurred claims and benefits	(13)	(6)	36	23
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	(1)	4	9
Other expenses	47	37	133	119
Total claims, benefits and expenses	35	30	173	151
Core income (loss) before income tax	(29)	(26)	(160)	(134)
Income tax (expense) benefit on core income (loss)	4	5	29	24
Core income (loss)	(25)	(21)	(131)	(110)
Eliminations
Operating revenues
Net earned premiums	0	(1)	0	(1)
Net investment income	0	0	0	0
Non-insurance warranty revenue	0	0	0	0
Other revenues	(2)	(1)	(5)	(4)
Total operating revenues	(2)	(2)	(5)	(5)
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	(1)	(1)	(1)	(1)
Other expenses	(1)	(1)	(4)	(4)
Total claims, benefits and expenses	(2)	(2)	(5)	(5)
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