Investments (Details) - Investment Information, Debt Securities - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Investment disclosure details
Fixed maturities, amortized cost	$ 95,401			$ 91,717
Allowance for expected credit losses	2			3
Gross unrealized gains	600			968
Gross unrealized losses	3,077			2,849
Fixed maturities, at fair value	92,922			89,833
Proceeds from sales of fixed maturities classified as available for sale	385	$ 601
Gross realized gains	1	3
Gross realized losses on sales of fixed maturities	30	26
Realized losses resulting from the early redemption of fixed maturities by the issuer prior to the bonds' maturity date	14	23
Amounts classified as held for sale [Member]
Investment disclosure details
Fixed maturities, amortized cost				3,221
Fixed maturities, at fair value				3,243
U.S. Treasury securities and obligations of U.S. government and government agencies and authorities [Member]
Investment disclosure details
Fixed maturities, amortized cost	3,380			3,927
Allowance for expected credit losses	0			0
Gross unrealized gains	1			11
Gross unrealized losses	100			81
Fixed maturities, at fair value	3,281			3,857
Obligations of U.S. states, municipalities and political subdivisions [Member]
Investment disclosure details
Fixed maturities, amortized cost	34,427			32,819
Allowance for expected credit losses	0			0
Gross unrealized gains	268			229
Gross unrealized losses	1,638			1,670
Fixed maturities, at fair value	33,057			31,378
Obligations of U.S. states, municipalities and political subdivisions, local general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	22,923			21,724
Allowance for expected credit losses	0			0
Gross unrealized gains	182			161
Gross unrealized losses	1,095			1,096
Fixed maturities, at fair value	22,010			20,789
Obligations of U.S. states, municipalities and political subdivisions, revenue [Member]
Investment disclosure details
Fixed maturities, amortized cost	10,252			9,810
Allowance for expected credit losses	0			0
Gross unrealized gains	79			58
Gross unrealized losses	515			543
Fixed maturities, at fair value	9,816			9,325
Obligations of U.S. states, municipalities and political subdivisions, state general obligation [Member]
Investment disclosure details
Fixed maturities, amortized cost	808			871
Allowance for expected credit losses	0			0
Gross unrealized gains	5			6
Gross unrealized losses	25			29
Fixed maturities, at fair value	788			848
Obligations of U.S. states, municipalities and political subdivisions, pre-refunded [Member]
Investment disclosure details
Fixed maturities, amortized cost	444			414
Allowance for expected credit losses	0			0
Gross unrealized gains	2			4
Gross unrealized losses	3			2
Fixed maturities, at fair value	443			416
Debt securities issued by foreign governments [Member]
Investment disclosure details
Fixed maturities, amortized cost	399			313
Allowance for expected credit losses	0			0
Gross unrealized gains	1			2
Gross unrealized losses	3			3
Fixed maturities, at fair value	397			312
Mortgage-backed securities, collateralized mortgage obligations and pass-through securities [Member]
Investment disclosure details
Fixed maturities, amortized cost	12,647			13,094
Allowance for expected credit losses	0			0
Gross unrealized gains	145			268
Gross unrealized losses	173			130
Fixed maturities, at fair value	12,619			13,232
Corporate and all other bonds [Member]
Investment disclosure details
Fixed maturities, amortized cost	44,548			41,564
Allowance for expected credit losses	2	$ 4	$ 3	3	$ 4	$ 2
Gross unrealized gains	185			458
Gross unrealized losses	1,163			965
Fixed maturities, at fair value	$ 43,568			$ 41,054

TRAVELERS COMPANIES, INC. 10-Q