Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2025

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Changes in the Net Carrying Amount of Goodwill by Operating Segment

The changes in the net carrying amount of goodwill for the years ended December 31, 2025 and 2024, respectively, are as follows (in millions):

	Risk Capital		Human Capital		Total
Balance as of January 1, 2024	$	6,227	$	2,187	$	8,414
Goodwill related to current year acquisitions	2,768		4,357		7,125
Goodwill related to current year disposals	(50)		(32)		(82)
Foreign currency translation and other	(160)		(63)		(223)
Balance as of December 31, 2024	$	8,785	$	6,449	$	15,234
Goodwill related to current year acquisitions	478		53		531
Goodwill related to current year disposals (1)	(7)		(398)		(405)
Goodwill related to prior year acquisitions	(11)		(10)		(21)
Foreign currency translation and other	306		152		458
Balance as of December 31, 2025	$	9,551	$	6,246	$	15,797

(1)Aon disposed of $398 million of Goodwill that related to the NFP Wealth business.

Schedule of Other Intangible Assets by Asset Class

Amortization basis and estimated useful lives by intangible asset type are generally as follows:

Intangible Asset Description	Amortization Basis	Estimated Useful Life
Customer-related and contract-based	In line with underlying cash flows	7 to 23 years
Tradenames	Straight-line	1 to 10.5 years
Technology and other intangibles	Straight-line	5 to 7 years

Other intangible assets by asset class are as follows (in millions):

	2025						2024
As of December 31	Gross Carrying Amount		Accumulated Amortization and Impairment		Net Carrying Amount (1)		Gross Carrying Amount		Accumulated Amortization and Impairment		Net Carrying Amount
Customer-related and contract-based	$	7,738	$	2,644	$	5,094	$	7,994	$	2,050	$	5,944
Tradenames	716		121		595		812		66		746
Technology and other	369		331		38		366		313		53
Total	$	8,823	$	3,096	$	5,727	$	9,172	$	2,429	$	6,743

(1)Aon disposed of $760 million of net intangible assets that related to the NFP Wealth business.

Schedule of Estimated Future Amortization Expense on Intangible Assets

The estimated future amortization for finite-lived intangible assets as of December 31, 2025 is as follows (in millions):

	Estimated Future Amortization
For the years ended
2026	$	670
2027	621
2028	568
2029	523
2030	475
Thereafter	2,870
Total	$	5,727