Share-Based Incentive Compensation (details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Feb. 02, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	May. 31, 2014
Summary of stock option activity
Stock options outstanding, beginning of year, number (in shares)		10,024,860
Granted (in shares)		2,244,464
Stock options exercised, number (in shares)		(2,310,548)
Stock options forfeited or expired, number (in shares)		(94,521)
Stock options outstanding, end of year, number (in shares)		9,864,255	10,024,860
Stock options outstanding, beginning of year, weighted average exercise price (per share)		$ 63.08
Stock options granted, weighted average exercise price (per share)		106.04
Stock options exercised, weighted average exercise price (per share)		55.16
Stock options forfeited or expired, weighted average exercise price (per share)		87.17
Stock options outstanding, end of year, weighted average exercise price (per share)		$ 74.48	$ 63.08
Stock options outstanding, weighted average contractual life remaining		6 years 7 months 6 days
Stock options outstanding, aggregate intrinsic value		$ 379
Stock options vested at end of year, number (in shares)		7,226,516
Stock options vested at end of year, weighted average exercise price (per share)		$ 68.80
Stock options vested at end of year, weighted average contractual life remaining		6 years
Stock options vested at end of year, aggregate intrinsic value		$ 318
Stock options exercisable at end of year, number (in shares)		4,155,912
Stock options exercisable at end of year, weighted average exercise price (per share)		$ 53.51
Stock options exercisable at end of year, weighted average contractual life remaining		4 years 3 months 18 days
Stock options exercisable at end of year, aggregate intrinsic value		$ 247
Stock option grants [Member]
Assumptions used in estimating fair value of options
Expected term of stock options		6 years	6 years	6 years
Expected volatility of the Company's stock (percent)		19.29%
Weighted average volatility (percent)		19.29%	27.50%	28.80%
Expected annual dividend per share		$ 2.20		$ 1.84
Risk-free rate		1.31%
Summary of stock option activity
Stock options granted, weighted average grant-date fair value of options granted (per share)		$ 15.78	$ 17.22	$ 17.09
Total intrinsic value of options exercised during the year		$ 120	$ 117	$ 122
Stock option grants [Member] | Minimum [Member]
Assumptions used in estimating fair value of options
Expected volatility of the Company's stock (percent)			27.20%	28.70%
Expected annual dividend per share			$ 2.00
Risk-free rate			1.81%	1.11%
Stock option grants [Member] | Maxiumum [Member]
Assumptions used in estimating fair value of options
Expected volatility of the Company's stock (percent)			27.50%	28.80%
Expected annual dividend per share			$ 2.20
Risk-free rate			1.82%	1.14%
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member]
Share-based compensation plan description
Number of shares of the Company's common stock authorized for grant under the 2014 Incentive Plan					10,000,000
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] | Stock option grants [Member]
Share-based compensation plan description
Option term		10 years
Vesting period		3 years
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] | Stock option grants [Member] | Subsequent Event [Member]
Summary of stock option activity
Granted (in shares)	2,808,558
Stock options granted, weighted average exercise price (per share)	$ 106.03
Stock options granted, weighted average grant-date fair value of options granted (per share)	$ 13.26
The Travelers Companies, Inc 2014 Stock Incentive Plan [Member] | Director deferred stock awards [Member]
Share-based compensation plan description
Number of days prior to date of annual meeting in year following date of grant in which annual deferred stock awards vest in full		1 day
Number of months after termination of service as a director before distributions of deferreed stock awards begin		6 months