Debt (Schedule of Debt Outstanding) (Details) € in Millions, $ in Millions		Dec. 31, 2022 USD ($)	Dec. 31, 2022 EUR (€)	Dec. 31, 2021 USD ($)	Mar. 31, 2000 USD ($)
Debt Instrument [Line Items]
Long-term debt		$ 14,402		$ 15,169
Short-term debt		475		999
Senior Notes | INA Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 475
Long-term debt stated interest rate		2.70%	2.70%
Long-term debt		$ 0		474
Make Whole Premium Additional Percent		0.10%	0.10%
Senior Notes | INA Senior Notes Due May 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 700
Long-term debt stated interest rate		3.35%	3.35%
Long-term debt		$ 699		698
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due December 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | €			€ 700
Long-term debt stated interest rate		0.30%	0.30%
Long-term debt		$ 742		787
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due March 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 800
Long-term debt stated interest rate		3.15%	3.15%
Long-term debt		$ 798		798
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due May 2026 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,500
Long-term debt stated interest rate		3.35%	3.35%
Long-term debt		$ 1,496		1,494
Make Whole Premium Additional Percent		0.20%	0.20%
Senior Notes | INA Senior Notes Due June 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | €			€ 575
Long-term debt stated interest rate		0.875%	0.875%
Long-term debt		$ 609		645
Make Whole Premium Additional Percent		0.20%	0.20%
Senior Notes | INA Senior Notes Due March 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | €			€ 900
Long-term debt stated interest rate		1.55%	1.55%
Long-term debt		$ 952		1,009
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due December 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | €			€ 700
Long-term debt stated interest rate		0.875%	0.875%
Long-term debt		$ 740		785
Make Whole Premium Additional Percent		0.20%	0.20%
Senior Notes | INA Senior Notes Due September 2030 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,000
Long-term debt stated interest rate		1.375%	1.375%
Long-term debt		$ 993		992
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due June 2031 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | €			€ 575
Long-term debt stated interest rate		1.40%	1.40%
Long-term debt		$ 606		642
Make Whole Premium Additional Percent		0.25%	0.25%
Senior Notes | INA Senior Notes Due May 2036 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 300
Long-term debt stated interest rate		6.70%	6.70%
Long-term debt		$ 298		298
Make Whole Premium Additional Percent		0.20%	0.20%
Senior Notes | INA Senior Notes Due May 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 800
Long-term debt stated interest rate		6.00%	6.00%
Long-term debt		$ 927		936
Make Whole Premium Additional Percent		0.20%	0.20%
Senior Notes | INA Senior Notes Due March 2038 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount | €			€ 900
Long-term debt stated interest rate		2.50%	2.50%
Long-term debt		$ 949		1,007
Make Whole Premium Additional Percent		0.25%	0.25%
Senior Notes | INA Senior Notes Due May 2038 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 600
Long-term debt stated interest rate		6.50%	6.50%
Long-term debt		$ 726		735
Make Whole Premium Additional Percent		0.30%	0.30%
Senior Notes | INA Senior Notes Due March 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 475
Long-term debt stated interest rate		4.15%	4.15%
Long-term debt		$ 471		470
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due November 2045 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,500
Long-term debt stated interest rate		4.35%	4.35%
Long-term debt		$ 1,485		1,485
Make Whole Premium Additional Percent		0.25%	0.25%
Senior Notes | INA Senior Notes Due December 2051 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 600
Long-term debt stated interest rate		2.85%	2.85%
Long-term debt		$ 593		593
Make Whole Premium Additional Percent		0.15%	0.15%
Senior Notes | INA Senior Notes Due December 2061 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,000
Long-term debt stated interest rate		3.05%	3.05%
Long-term debt		$ 984		983
Make Whole Premium Additional Percent		0.20%	0.20%
Trust Preferred Securities | Chubb INA Capital Securities Due 2030 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 309			$ 300
Long-term debt stated interest rate		9.70%	9.70%		9.70%
Trust preferred securities	[1]	$ 308		308
Unsecured Debt | INA Senior Notes Due August 2029 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 100
Long-term debt stated interest rate		8.875%	8.875%
Long-term debt		$ 100		100
Unsecured Debt | INA Senior Notes Due November 2031 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 200
Long-term debt stated interest rate		6.80%	6.80%
Long-term debt		$ 234		$ 238
Make Whole Premium Additional Percent		0.25%	0.25%
Repurchase agreements
Debt Instrument [Line Items]
Weighted average interest rate on short-term debt		3.90%	3.90%	0.20%
Short-term debt		$ 1,419		$ 1,406
Senior Notes | INA Senior Notes Due November 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 1,000
Long-term debt stated interest rate		2.875%	2.875%
Make Whole Premium Additional Percent		0.20%	0.20%
Short-term debt		$ 0		999
Senior Notes | INA Senior Notes Due March 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount		$ 475
Long-term debt stated interest rate		2.70%	2.70%
Make Whole Premium Additional Percent		0.10%	0.10%
Short-term debt		$ 475		$ 0

[1] Redemption prices are equal to accrued and unpaid interest to the redemption date plus the greater of (i) 100 percent of the principal amount thereof, or (ii) sum of present value of scheduled payments of principal and interest on the capital securities from the redemption date to April 1, 2030.