Debt (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Schedule of Current and Long-term Debt

Current debt consists of the following:

	December 31,
	2023		2022
4.625% senior notes due 2023	$	—	$	250
3.600% senior notes due 2024		650		—
	$	650	$	250

Long-term debt consists of the following:

	December 31,
	2023		2022
Revolving $1.5 billion credit facility	$	—	$	—
3.600% senior notes due 2024		—		649
4.400% senior notes due 2026		548		547
4.650% senior notes due 2027		745		744
4.500% senior notes due 2028		598		597
2.950% senior notes due 2029		726		726
5.350% senior notes due 2033		741		—
6.125% senior notes due 2043		272		271
5.050% senior notes due 2048		395		395
3.875% senior notes due 2049		542		542
	$	4,567	$	4,471

Summary of Entities

The following table presents a summary of the entities that issued each note or entered into the revolving credit facility and those wholly-owned and consolidated subsidiaries of the Company that guarantee each respective note and the revolving credit facility on a joint and several basis as of December 31, 2023.

Entity	Revolving credit facility 4.400% due 2026 6.125% due 2043	3.600% due 2024 4.650% due 2027  4.500% due 2028 2.950% due 2029 5.350% due 2033 5.050% due 2048 3.875% due 2049
Willis Towers Watson plc	Guarantor	Guarantor
Trinity Acquisition plc	Issuer	Guarantor
Willis North America Inc.	Guarantor	Issuer
Willis Netherlands Holdings B.V.	Guarantor	Guarantor
Willis Investment UK Holdings Limited	Guarantor	Guarantor
TA I Limited	Guarantor	Guarantor
Willis Group Limited	Guarantor	Guarantor
Willis Towers Watson Sub Holdings Unlimited Company	Guarantor	Guarantor
Willis Towers Watson UK Holdings Limited	Guarantor	Guarantor

Schedule of Maturities of Long-term Debt

The following table summarizes the maturity of our debt and interest on senior notes and excludes any reduction for debt issuance costs:

	2024		2025		2026		2027		2028		Thereafter		Total
Senior notes	$	650	$	—	$	550	$	750	$	600	$	2,700	$	5,250
Interest on senior notes		214		206		187		163		139		1,276		2,185
Revolving $1.5 billion credit facility		—		—		—		—		—		—		—
Total	$	864	$	206	$	737	$	913	$	739	$	3,976	$	7,435

Schedule of Debt Interest Expense

The following table shows an analysis of the interest expense for the years ended December 31, 2023, 2022 and 2021:

	Years ended December 31,
	2023		2022		2021
Senior notes	$	227	$	196	$	200
Revolving credit facility		3		3		3
Collateralized facility		—		—		2
Other (i)		5		9		6
Total interest expense	$	235	$	208	$	211

(i)Other primarily includes interest expense on finance leases and accretion on deferred and contingent consideration.