Employee Benefits (Tables)

3 Months Ended

Mar. 31, 2022

Retirement Benefits [Abstract]

Schedule of Components of Net Periodic Benefit Cost for the Pension Plans

The following table provides the components of the net periodic (benefit) cost recognized in the Condensed Consolidated Statements of Income for Aon’s significant U.K., U.S., and other major pension plans, which are located in the Netherlands and Canada. Service cost is reported in Compensation and benefits and all other components are reported in Other income (expense) as follows (in millions):

	Three Months Ended March 31,
	U.K.				U.S.				Other
	2022		2021		2022		2021		2022		2021
Service cost	$	—	$	—	$	—	$	—	$	—	$	—
Interest cost	23		16		17		14		5		3
Expected return on plan assets, net of administration expenses	(36)		(34)		(27)		(32)		(9)		(8)
Amortization of prior-service cost	1		1		—		—		—		—
Amortization of net actuarial loss	7		8		16		19		4		4
Net periodic (benefits) cost	(5)		(9)		6		1		—		(1)
Loss on pension settlement	—		—		1		—		—		—
Total net periodic (benefit) cost	$	(5)	$	(9)	$	7	$	1	$	—	$	(1)

Schedule of Employer's Contributions

The following table summarizes contributions made to the Company’s significant pension plans (in millions):

	Three Months Ended March 31,
	2022		2021
Contributions to U.K. pension plans	$	3	$	4
Contributions to U.S. pension plans	18		38
Contributions to other major pension plans	8		8
Total contributions	$	29	$	50