Segment Information - Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Earned premiums and fee income	$ 5,013	$ 4,698
Net investment income	509	509
Net realized gains (losses)	(145)	80
Other revenues	16	12
Total revenues	5,393	5,299
Corporate
Segment Reporting Information [Line Items]
Earned premiums and fee income	13	12
Commercial Lines | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income	2,495	2,244
Commercial Lines | Operating Segments [Member] | Workers’ compensation
Segment Reporting Information [Line Items]
Earned premiums and fee income	835	738
Commercial Lines | Operating Segments [Member] | Liability
Segment Reporting Information [Line Items]
Earned premiums and fee income	424	375
Commercial Lines | Operating Segments [Member] | Marine
Segment Reporting Information [Line Items]
Earned premiums and fee income	61	58
Commercial Lines | Operating Segments [Member] | Package business
Segment Reporting Information [Line Items]
Earned premiums and fee income	435	393
Commercial Lines | Operating Segments [Member] | Property
Segment Reporting Information [Line Items]
Earned premiums and fee income	190	200
Commercial Lines | Operating Segments [Member] | Professional liability
Segment Reporting Information [Line Items]
Earned premiums and fee income	178	155
Commercial Lines | Operating Segments [Member] | Bond
Segment Reporting Information [Line Items]
Earned premiums and fee income	72	69
Commercial Lines | Operating Segments [Member] | Assumed reinsurance
Segment Reporting Information [Line Items]
Earned premiums and fee income	100	68
Commercial Lines | Operating Segments [Member] | Automobile
Segment Reporting Information [Line Items]
Earned premiums and fee income	200	188
Personal Lines | AARP Members [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income	667	676
Personal Lines | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income	728	742
Personal Lines | Operating Segments [Member] | Property
Segment Reporting Information [Line Items]
Earned premiums and fee income	229	230
Personal Lines | Operating Segments [Member] | Automobile
Segment Reporting Information [Line Items]
Earned premiums and fee income	499	512
Group Benefits | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income	1,490	1,418
Group Benefits | Operating Segments [Member] | Group disability
Segment Reporting Information [Line Items]
Earned premiums and fee income	806	739
Group Benefits | Operating Segments [Member] | Group life
Segment Reporting Information [Line Items]
Earned premiums and fee income	597	602
Group Benefits | Operating Segments [Member] | Other
Segment Reporting Information [Line Items]
Earned premiums and fee income	87	77
Hartford Funds | Operating Segments [Member]
Segment Reporting Information [Line Items]
Earned premiums and fee income	287	282
Hartford Funds | Operating Segments [Member] | Mutual fund and Exchange-Traded Funds ("ETF")
Segment Reporting Information [Line Items]
Earned premiums and fee income	265	259
Hartford Funds | Operating Segments [Member] | Talcott Resolution life and annuity separate accounts [2]
Segment Reporting Information [Line Items]
Earned premiums and fee income	$ 22	$ 23