Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2025

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
	2025		2024		2023
Commercial Risk Solutions	$	8,497	$	7,861	$	7,043
Reinsurance Solutions	2,793		2,656		2,481
Total Risk Capital (1)	11,290		10,517		9,524
Health Solutions	3,839		3,335		2,433
Wealth Solutions	2,068		1,874		1,431
Total Human Capital (1)	5,907		5,209		3,864
Eliminations	(16)		(28)		(12)
Total revenue	$	17,181	$	15,698	$	13,376

(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, 2025
	Risk Capital		Human Capital		Corporate/Eliminations		Total
U.S.	$	4,991	$	3,304	$	(16)	$	8,279
Americas other than U.S.	1,131		502		—		1,633
U.K.	1,409		811		—		2,220
Ireland	95		90		—		185
Europe, Middle East, & Africa other than U.K. and Ireland	2,321		832		—		3,153
Asia Pacific	1,343		368		—		1,711
Total revenue	$	11,290	$	5,907	$	(16)	$	17,181

	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

Schedule of Capitalized Contract Cost

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

	2025		2024
Balance at beginning of period	$	424	$	370
Additions	1,849		1,725
Amortization	(1,839)		(1,659)
Impairment	—		—
Foreign currency translation and other	16		(12)
Balance at end of period	$	450	$	424

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

	2025		2024
Balance at beginning of period	$	207	$	195
Additions	63		73
Amortization	(68)		(54)
Impairment	—		—
Foreign currency translation and other	6		(7)
Balance at end of period	$	208	$	207