Employee Benefits (Tables)

3 Months Ended

Mar. 31, 2017

Compensation and Retirement Disclosure [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 in Compensation and benefits for Aon’s material U.K., U.S., and other significant international pension plans located in the Netherlands and Canada (in millions):

	Three months ended March 31
	U.K.						U.S.						Other
	2017			2016			2017			2016			2017			2016
Service cost	$	—		$	—		$	—		$	—		$	—		$	—
Interest cost	30			43			24			28			6			7
Expected return on plan assets, net of administration expenses	(48		)	(64		)	(35		)	(39		)	(11		)	(12		)
Amortization of prior-service cost	—			1			—			—			—			—
Amortization of net actuarial loss	7			8			13			13			3			3
Net periodic (benefit) cost	$	(11	)	$	(12	)	$	2		$	2		$	(2	)	$	(2	)