Debt (Details) - Junior Subordinated Debt $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) debenture_instruments trusts	Dec. 31, 2020 USD ($)
Debt Instrument
Unamortized fair value adjustment	$ 39	$ 41
Junior Subordinated Debt [Member]
Debt Instrument
Number of junior subordinated debentures that are all similar in nature | debenture_instruments	3
Number of separate trusts that issued preferred securities and used proceeds to purchase the Company's subordinated debentures | trusts	3
Impact of amortization of the fair value adjustment on interest expense	$ 2	$ 2
Junior Subordinated Debt [Member] | 7.625% Junior subordinated debentures due December 15, 2027 [Member]
Debt Instrument
Interest rate (percent)	7.625%	7.625%
Effective interest rate (percent)	6.147%
Unamortized fair value adjustment	$ 8	$ 10
Junior Subordinated Debt [Member] | 8.50% Junior subordinated debentures due December 15, 2045 [Member]
Debt Instrument
Interest rate (percent)	8.50%	8.50%
Effective interest rate (percent)	6.362%
Unamortized fair value adjustment	$ 14	$ 14
Junior Subordinated Debt [Member] | 8.312% Junior subordinated debentures due July 1, 2046 [Member]
Debt Instrument
Interest rate (percent)	8.312%	8.312%
Effective interest rate (percent)	6.362%
Unamortized fair value adjustment	$ 17	$ 17
Senior Notes [Member] | 7.75% Senior notes due April 15, 2026 [Member]
Debt Instrument
Interest rate (percent)	7.75%	7.75%
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 200
Senior Notes [Member] | 6.375% Senior notes due March 15, 2033 [Member]
Debt Instrument
Interest rate (percent)	6.375%	6.375%
Amount of certain debt obligations of Travelers Property Casualty Corp. (TPC) and Travelers Insurance Group Holdings, Inc. (TIGHI) that are fully and unconditionally guaranteed by The Travelers Companies, Inc.	$ 500