Business Segments (Income Statement Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating revenues
Net earned premiums	$ 2,248	$ 2,059	[1]
Net investment income	525	448	[1]
Non-insurance warranty revenue	407	382	[1]
Other revenues	7	7	[1]
Total operating revenues	3,187	2,896
Claims, Benefits and Expenses
Net incurred claims and benefits	1,646	1,472
Policyholders’ dividends	7	6
Amortization of deferred acquisition costs	379	344	[1]
Non-insurance warranty expense	384	354	[1]
Other insurance related expenses	305	291
Other expenses	60	63
Total claims, benefits and expenses	2,781	2,530	[1]
Core income (loss) before income tax	406	366
Income tax (expense) benefit on core income (loss)	(81)	(68)
Core income (loss)	325	298
Net investment gains (losses)	(35)	(11)
Income tax (expense) benefit on net investment gains (losses)	7	8
Net investment gains (losses), after tax	(28)	(3)
Net income (loss)	297	295
Operating Segments | Specialty
Operating revenues
Net earned premiums	797	772
Net investment income	129	103
Non-insurance warranty revenue	407	382
Other revenues	0	1
Total operating revenues	1,333	1,258
Claims, Benefits and Expenses
Net incurred claims and benefits	465	445
Policyholders’ dividends	1	1
Amortization of deferred acquisition costs	165	157
Non-insurance warranty expense	384	354
Other insurance related expenses	86	81
Other expenses	14	13
Total claims, benefits and expenses	1,115	1,051
Core income (loss) before income tax	218	207
Income tax (expense) benefit on core income (loss)	(47)	(44)
Core income (loss)	171	163
Operating Segments | Commercial
Operating revenues
Net earned premiums	1,046	904
Net investment income	149	118
Non-insurance warranty revenue	0	0
Other revenues	7	8
Total operating revenues	1,202	1,030
Claims, Benefits and Expenses
Net incurred claims and benefits	688	573
Policyholders’ dividends	6	5
Amortization of deferred acquisition costs	169	148
Non-insurance warranty expense	0	0
Other insurance related expenses	142	130
Other expenses	6	7
Total claims, benefits and expenses	1,011	863
Core income (loss) before income tax	191	167
Income tax (expense) benefit on core income (loss)	(40)	(35)
Core income (loss)	151	132
Operating Segments | International
Operating revenues
Net earned premiums	290	264
Net investment income	23	14
Non-insurance warranty revenue	0	0
Other revenues	0	(1)
Total operating revenues	313	277
Claims, Benefits and Expenses
Net incurred claims and benefits	189	158
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	45	39
Non-insurance warranty expense	0	0
Other insurance related expenses	47	47
Other expenses	1	1
Total claims, benefits and expenses	282	245
Core income (loss) before income tax	31	32
Income tax (expense) benefit on core income (loss)	(7)	(6)
Core income (loss)	24	26
Operating Segments | Life & Group
Operating revenues
Net earned premiums	115	120
Net investment income	214	212
Non-insurance warranty revenue	0	0
Other revenues	0	(1)
Total operating revenues	329	331
Claims, Benefits and Expenses
Net incurred claims and benefits	311	304
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	0	0
Non-insurance warranty expense	0	0
Other insurance related expenses	29	31
Other expenses	1	3
Total claims, benefits and expenses	341	338
Core income (loss) before income tax	(12)	(7)
Income tax (expense) benefit on core income (loss)	9	12
Core income (loss)	(3)	5
Operating Segments | Corporate & Other
Operating revenues
Net earned premiums	0	(1)
Net investment income	10	1
Non-insurance warranty revenue	0	0
Other revenues	3	2
Total operating revenues	13	2
Claims, Benefits and Expenses
Net incurred claims and benefits	(7)	(8)
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	0	0
Non-insurance warranty expense	0	0
Other insurance related expenses	1	2
Other expenses	41	41
Total claims, benefits and expenses	35	35
Core income (loss) before income tax	(22)	(33)
Income tax (expense) benefit on core income (loss)	4	5
Core income (loss)	(18)	(28)
Eliminations
Operating revenues
Net earned premiums	0	0
Net investment income	0	0
Non-insurance warranty revenue	0	0
Other revenues	(3)	(2)
Total operating revenues	(3)	(2)
Claims, Benefits and Expenses
Net incurred claims and benefits	0	0
Policyholders’ dividends	0	0
Amortization of deferred acquisition costs	0	0
Non-insurance warranty expense	0	0
Other insurance related expenses	0	0
Other expenses	(3)	(2)
Total claims, benefits and expenses	(3)	(2)
Core income (loss) before income tax	0	0
Income tax (expense) benefit on core income (loss)	0	0
Core income (loss)	$ 0	$ 0

[1] As of January 1, 2023, the Company adopted ASU 2018-12, Financial Services-Insurance (Topic 944): Targeted Improvements to the Accounting for Long-Duration Contracts (ASU 2018-12) using the modified retrospective method applied as of the transition date of January 1, 2021. Prior period amounts in the financial statements have been adjusted to reflect application of the new guidance. See Note A to the Condensed Consolidated Financial Statements for additional information.