Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2019

Retirement Benefits [Abstract]

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 international pension plans. 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 June 30
	U.K.						U.S.						Other
	2019			2018			2019			2018			2019			2018
Service cost	$	—		$	—		$	—		$	—		$	—		$	—
Interest cost	27			29			27			25			7			7
Expected return on plan assets, net of administration expenses	(48		)	(50		)	(34		)	(36		)	(10		)	(11		)
Amortization of prior-service cost	—			—			—			1			—			—
Amortization of net actuarial loss	8			7			14			15			3			3
Net periodic (benefit) cost	(13		)	(14		)	7			5			—			(1		)
Loss on pension settlement	—			16			—			—			—			—
Total net periodic (benefit) cost	$	(13	)	$	2		$	7		$	5		$	—		$	(1	)

	Six Months Ended June 30
	U.K.						U.S.						Other
	2019			2018			2019			2018			2019			2018
Service cost	$	—		$	—		$	—		$	—		$	—		$	—
Interest cost	55			58			54			50			14			14
Expected return on plan assets, net of administration expenses	(97		)	(101		)	(68		)	(72		)	(20		)	(23		)
Amortization of prior-service cost	1			—			1			1			—			—
Amortization of net actuarial loss	15			15			27			30			6			6
Net periodic (benefit) cost	(26		)	(28		)	14			9			—			(3		)
Loss on pension settlement	—			23			—			—			—			—
Total net periodic (benefit) cost	$	(26	)	$	(5	)	$	14		$	9		$	—		$	(3	)