Shareholders' equity AOCI Reclassifications (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 672	$ 570	$ 492
Income tax expense	511	1,239	1,269
Net income attributable to Chubb	9,028	5,246	8,525
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income attributable to Chubb	(401)	(797)	9
Reclassification out of Accumulated Other Comprehensive Income [Member] | AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Debt Securities, Available-for-sale, Realized Gain (Loss), Excluding Other-than-temporary Impairment	(500)	(1,049)	3
Income tax expense	62	170	6
Net income attributable to Chubb	(438)	(879)	9
Reclassification out of Accumulated Other Comprehensive Income [Member] | Cumulative Translation Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	13	4	0
Income tax expense	(3)	(1)	0
Net income attributable to Chubb	10	3	0
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Foreign Currency Transaction Gain (Loss), Realized	50	105	0
Interest expense	(16)	(5)	0
Income tax expense	(7)	(21)	0
Net income attributable to Chubb	$ 27	$ 79	$ 0