Agreement termination date.

No definition available.

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- Definition

Amount payable to redeem notes percent of principal amount following transaction termination event.

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No definition available.

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- Definition

Debt Instrument Maturity Year

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No definition available.

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- Definition

Debt instrument redemption date.

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No definition available.

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- Definition

Number of days to occur reinsurance transaction termination event for note redemption.

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No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

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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No definition available.

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- Definition

Weighted average interest rate of debt outstanding.

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- Definition

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

The difference between the reacquisition price and the net carrying amount of the extinguished debt recognized currently as a component of income in the period of extinguishment, net of tax.

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- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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- Definition

The fair value of notes issued in noncash investing and financing activities.

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Credit and Other Debt Agreements - Additional Information (Detail) - USD ($)			3 Months Ended
	Jul. 29, 2021	May 20, 2021	Sep. 30, 2021	Jun. 30, 2021
Subsequent Event [Member] \| Willis Towers Watson PLC [Member]
Debt Instrument [Line Items]
Agreement termination date	Jul. 29, 2021
Private Placement [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 1,500,000,000.0
Weighted average interest rate		3.31%
Realized a cash gain (loss) on hedging transaction		$ (57,800,000)
Derivative instrument, term		10 years
Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest				2.50%
Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Amount payable to redeem the notes, percent of the principal amount following transaction termination event		101.00%
Number of days to occur reinsurance transaction termination event for note redemption		30 days
Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member] \| Unsecured Senior Notes [Member] \| Scenario, Forecast [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Extinguishment of debt after tax loss			$ 12,000,000.0
Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member] \| Unsecured Senior Notes [Member] \| Scenario, Forecast [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Extinguishment of debt after tax loss			$ 14,000,000.0
Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member] \| Private Placement [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 650,000,000.0
Periodic Payment of Interest		2.50%
Periodic payments of interest and principal, expiry year		2031
Fixed Rate of 2.50%, Balloon Due May 20, 2031 [Member] \| Private Placement [Member] \| Unsecured Senior Notes [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Notes redemption date	Aug. 13, 2021
Fixed Rate of 3.50%, Balloon Due May 20, 2051 [Member]
Debt Instrument [Line Items]
Periodic Payment of Interest				3.50%
Fixed Rate of 3.50%, Balloon Due May 20, 2051 [Member] \| Private Placement [Member] \| Unsecured Senior Notes [Member]
Debt Instrument [Line Items]
Notes issued and sold		$ 850,000,000.0
Periodic Payment of Interest		3.50%
Periodic payments of interest and principal, expiry year		2051