Schedule III Supplementary Insurance Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	$ 881	$ 789
Unpaid Losses and Loss Adjustment Expenses	39,659	37,855
Reserve for Future Policy Benefits	596	638
Unearned Premiums	7,194	6,629
Other Policyholder Funds and Benefits Payable	687	701
Earned Premiums, Fee Income and Other	19,568	18,691	$ 18,394
Net Investment Income	2,313	1,846	1,951
Benefits, Losses and Loss Adjustment Expenses	12,729	11,805	11,472
Amortization of Deferred Policy Acquisition Costs	1,680	1,706	1,622
Insurance Operating Costs and Other Expenses	5,085	4,892	5,086
Net Written Premiums	12,949	11,914	11,595
Group Insurance Policy [Member]
Schedule of Supplementary Insurance Information [Abstract]
Unpaid Losses and Loss Adjustment Expenses	8,210	8,233	8,256	$ 8,445
Operating Segments | Property and Casualty, Commercial Insurance [Member]
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	742	641
Unpaid Losses and Loss Adjustment Expenses	26,906	25,058
Reserve for Future Policy Benefits	0	0
Unearned Premiums	5,693	5,081
Other Policyholder Funds and Benefits Payable	0	0
Earned Premiums, Fee Income and Other	9,586	8,941	8,326
Net Investment Income	1,502	1,160	1,129
Benefits, Losses and Loss Adjustment Expenses	6,044	5,929	5,192
Amortization of Deferred Policy Acquisition Costs	1,398	1,397	1,296
Insurance Operating Costs and Other Expenses	1,747	1,683	1,776
Net Written Premiums	10,041	8,969	8,452
Operating Segments | Property and Casualty, Personal Insurance [Member]
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	101	103
Unpaid Losses and Loss Adjustment Expenses	1,844	1,836
Reserve for Future Policy Benefits	0	0
Unearned Premiums	1,459	1,506
Other Policyholder Funds and Benefits Payable	0	0
Earned Premiums, Fee Income and Other	3,066	3,123	3,318
Net Investment Income	157	157	179
Benefits, Losses and Loss Adjustment Expenses	1,864	1,466	2,185
Amortization of Deferred Policy Acquisition Costs	230	244	259
Insurance Operating Costs and Other Expenses	678	663	702
Net Written Premiums	2,908	2,936	3,131
Operating Segments | Property & Casualty Other Operations
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	0	0
Unpaid Losses and Loss Adjustment Expenses	2,699	2,728
Reserve for Future Policy Benefits	0	0
Unearned Premiums	2	2
Other Policyholder Funds and Benefits Payable	0	0
Earned Premiums, Fee Income and Other	0	0	2
Net Investment Income	75	55	84
Benefits, Losses and Loss Adjustment Expenses	202	258	21
Amortization of Deferred Policy Acquisition Costs	0	0	0
Insurance Operating Costs and Other Expenses	9	10	12
Net Written Premiums	0	0	0
Operating Segments | Group Insurance Policy [Member]
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	31	38
Unpaid Losses and Loss Adjustment Expenses	8,210	8,233
Reserve for Future Policy Benefits	399	420
Unearned Premiums	40	40
Other Policyholder Funds and Benefits Payable	426	415
Earned Premiums, Fee Income and Other	5,687	5,536	5,603
Net Investment Income	550	448	486
Benefits, Losses and Loss Adjustment Expenses	4,612	4,137	4,055
Amortization of Deferred Policy Acquisition Costs	40	50	54
Insurance Operating Costs and Other Expenses	1,413	1,348	1,352
Net Written Premiums	0	0	0
Operating Segments | Hartford Funds
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	7	7
Unpaid Losses and Loss Adjustment Expenses	0	0
Reserve for Future Policy Benefits	0	0
Unearned Premiums	0	0
Other Policyholder Funds and Benefits Payable	0	0
Earned Premiums, Fee Income and Other	1,189	989	999
Net Investment Income	5	4	7
Benefits, Losses and Loss Adjustment Expenses	0	0	0
Amortization of Deferred Policy Acquisition Costs	12	14	12
Insurance Operating Costs and Other Expenses	913	773	813
Net Written Premiums	0	0	0
Corporate
Schedule of Supplementary Insurance Information [Abstract]
Deferred Policy Acquisition Costs	0	0
Unpaid Losses and Loss Adjustment Expenses	0	0
Reserve for Future Policy Benefits	197	218
Unearned Premiums	0	0
Other Policyholder Funds and Benefits Payable	261	286
Earned Premiums, Fee Income and Other	40	102	146
Net Investment Income	24	22	66
Benefits, Losses and Loss Adjustment Expenses	7	15	19
Amortization of Deferred Policy Acquisition Costs	0	1	1
Insurance Operating Costs and Other Expenses	325	415	431
Net Written Premiums	$ 0	$ 9	$ 12