Share-Based Compensation (Detail) - $ / shares		9 Months Ended
Feb. 25, 2021	Sep. 30, 2021
Chubb Limited Amended 2016 Long-Term Incentive Plan \| Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized		13,400,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period in years		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period		3 years
Award term period in years		10 years
Stock options granted	1,790,057
Weighted-average grant date fair value for stock options granted	$ 33.05
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period in years		4 years
Restricted stock awards granted to employees and officers of the company	848,762
Grant date fair value of awards except for options granted to employees and officers of the company	$ 164.94
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period in years		3 years
Restricted stock awards granted to employees and officers of the company	284,766
Grant date fair value of awards except for options granted to employees and officers of the company	$ 164.94
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period in years		4 years
Restricted stock awards granted to employees and officers of the company	324,142
Grant date fair value of awards except for options granted to employees and officers of the company	$ 164.94

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under share-based payment arrangement.

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Net number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of shares issued under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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