Segment Information - Revenues (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Earned premiums and fee income									$ 22,326	$ 20,739	$ 19,487
Total net investment income									2,305	2,177	2,313
Net realized gains (losses)									(188)	(627)	509
Other revenues									84	73	81
Revenues	$ 6,400	$ 6,168	$ 6,049	$ 5,910	$ 6,016	$ 5,580	$ 5,373	$ 5,393	24,527	22,362	22,390
P&C Personal Lines | AARP Members
Segment Reporting Information [Line Items]
Earned premiums and fee income									2,900	2,700	2,700
Corporate
Segment Reporting Information [Line Items]
Earned premiums and fee income									39	49	50
Total net investment income									47	26	24
Operating Segments | P&C Commercial Lines
Segment Reporting Information [Line Items]
Earned premiums and fee income									11,682	10,610	9,575
Total net investment income									1,532	1,415	1,502
Operating Segments | P&C Commercial Lines | Workers’ compensation
Segment Reporting Information [Line Items]
Earned premiums and fee income									3,670	3,499	3,172
Operating Segments | P&C Commercial Lines | General liability
Segment Reporting Information [Line Items]
Earned premiums and fee income									1,977	1,836	1,622
Operating Segments | P&C Commercial Lines | Marine [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income									256	235	228
Operating Segments | P&C Commercial Lines | Package business
Segment Reporting Information [Line Items]
Earned premiums and fee income									2,076	1,844	1,665
Operating Segments | P&C Commercial Lines | Property
Segment Reporting Information [Line Items]
Earned premiums and fee income									1,053	845	829
Operating Segments | P&C Commercial Lines | Professional liability
Segment Reporting Information [Line Items]
Earned premiums and fee income									787	737	655
Operating Segments | P&C Commercial Lines | Bond
Segment Reporting Information [Line Items]
Earned premiums and fee income									321	303	287
Operating Segments | P&C Commercial Lines | Assumed Reinsurance [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income									615	467	328
Operating Segments | P&C Commercial Lines | Automobile
Segment Reporting Information [Line Items]
Earned premiums and fee income									927	844	789
Operating Segments | P&C Personal Lines
Segment Reporting Information [Line Items]
Earned premiums and fee income									3,117	2,979	2,986
Total net investment income									171	140	157
Operating Segments | P&C Personal Lines | Property
Segment Reporting Information [Line Items]
Earned premiums and fee income									961	932	927
Operating Segments | P&C Personal Lines | Automobile
Segment Reporting Information [Line Items]
Earned premiums and fee income									2,156	2,047	2,059
Operating Segments | Property & Casualty Other Operations
Segment Reporting Information [Line Items]
Earned premiums and fee income									0	0	0
Total net investment income									69	63	75
Operating Segments | Group Benefits [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income									6,515	6,057	5,687
Total net investment income									469	524	550
Operating Segments | Group Benefits [Member] | Group disability
Segment Reporting Information [Line Items]
Earned premiums and fee income									3,530	3,310	2,983
Operating Segments | Group Benefits [Member] | Group life
Segment Reporting Information [Line Items]
Earned premiums and fee income									2,583	2,393	2,388
Operating Segments | Group Benefits [Member] | Other
Segment Reporting Information [Line Items]
Earned premiums and fee income									402	354	316
Operating Segments | Hartford Funds
Segment Reporting Information [Line Items]
Earned premiums and fee income									973	1,044	1,189
Total net investment income									17	9	5
Operating Segments | Hartford Funds | Third party retail customers [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income									900	964	1,094
Operating Segments | Hartford Funds | Talcott Resolution [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income									$ 73	$ 80	$ 95