Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2024

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

The following table summarizes revenue from contracts with customers by principal service line (in millions):

	Years Ended December 31
	2024		2023		2022
Commercial Risk Solutions	$	7,861	$	7,043	$	6,715
Reinsurance Solutions	2,656		2,481		2,190
Total Risk Capital (1)	10,517		9,524		8,905
Health Solutions	3,335		2,433		2,224
Wealth Solutions	1,874		1,431		1,367
Total Human Capital (1)	5,209		3,864		3,591
Eliminations	(28)		(12)		(17)
Total revenue	$	15,698	$	13,376	$	12,479

(1)Includes inter-segment revenue. Refer to Note 17 “Segment Information” for further information.

Consolidated revenue from contracts with customers by geographic area, which is attributed on the basis of where the services are performed, is as follows (in millions):

	Year Ended December 31, 2024
	Risk Capital		Human Capital		Corporate/Eliminations		Total
U.S.	$	4,697	$	2,997	$	(28)	$	7,666
Americas other than U.S.	954		381		—		1,335
U.K.	1,266		709		—		1,975
Ireland	78		68		—		146
Europe, Middle East, & Africa other than U.K. and Ireland	2,176		724		—		2,900
Asia Pacific	1,346		330		—		1,676
Total revenue	$	10,517	$	5,209	$	(28)	$	15,698

	Year Ended December 31, 2023
	Risk Capital		Human Capital		Corporate/Eliminations		Total
U.S.	$	4,067	$	1,868	$	(12)	$	5,923
Americas other than U.S.	909		351		—		1,260
U.K.	1,186		633		—		1,819
Ireland	61		52		—		113
Europe, Middle East, & Africa other than U.K. and Ireland	2,036		636		—		2,672
Asia Pacific	1,265		324		—		1,589
Total revenue	$	9,524	$	3,864	$	(12)	$	13,376

	Year Ended December 31, 2022
	Risk Capital		Human Capital		Corporate/Eliminations		Total
U.S.	$	3,910	$	1,773	$	(17)	$	5,666
Americas other than U.S.	837		300		—		1,137
U.K.	1,068		592		—		1,660
Ireland	53		46		—		99
Europe, Middle East, & Africa other than U.K. and Ireland	1,877		566		—		2,443
Asia Pacific	1,160		314		—		1,474
Total revenue	$	8,905	$	3,591	$	(17)	$	12,479

Schedule of Capitalized Contract Cost

Changes in the net carrying amount of costs to fulfill contracts with customers are as follows (in millions):

	2024		2023
Balance at beginning of period	$	370	$	355
Additions	1,725		1,532
Amortization	(1,659)		(1,522)
Impairment	—		—
Foreign currency translation and other	(12)		5
Balance at end of period	$	424	$	370

Changes in the net carrying amount of costs to obtain contracts with customers are as follows (in millions):

	2024		2023
Balance at beginning of period	$	195	$	185
Additions	73		57
Amortization	(54)		(51)
Impairment	—		—
Foreign currency translation and other	(7)		4
Balance at end of period	$	207	$	195