Share-Based Compensation Plans

The following table summarizes share-based compensation expense recognized in the Consolidated Statements of Income in Compensation and benefits (in millions):



Years ended December 31	2017		2016		2015
Restricted share units (“RSUs”)	$	182	$	176	$	186
Performance share awards ("PSAs")	127		120		123
Employee share purchase plans	10		10		9
Total share-based compensation expense	319		306		318
Tax benefit	73		90		87
Share-based compensation expense, net of tax	$	246	$	216	$	231

Restricted Share Units

RSUs generally vest between three and five years. The fair value of RSUs is based upon the market value of Aon plc ordinary shares at the date of grant. With certain limited exceptions, any break in continuous employment will cause the forfeiture of all non-vested awards. Compensation expense associated with RSUs is recognized on a straight-line basis over the requisite service period. Dividend equivalents are paid on certain RSUs, based on the initial grant amount.

The following table summarizes the status of the Company’s RSUs, including shares related to the Divested Business (shares in

thousands):



Years ended December 31	2017				2016				2015
	Shares		Fair Value ⁽¹⁾		Shares		Fair Value ⁽¹⁾		Shares		Fair Value ⁽¹⁾
Non-vested at beginning of year	6,195		$	89	7,167		$	77	8,381		$	63
Granted	1,700		123		2,252		101		2,459		97
Vested	(2,407	)	82		(2,845	)	70		(3,385	)	58
Forfeited	(639	)	93		(379	)	82		(288	)	71
Non-vested at end of year	4,849		$	104	6,195		$	89	7,167		$	77


(1)	Represents per share weighted average fair value of award at date of grant.

The fair value of RSUs that vested during 2017, 2016 and 2015 was $197 million, $200 million, and $196 million, respectively.

Unamortized deferred compensation expense amounted to $341 million as of December 31, 2017, with a remaining weighted-average amortization period of approximately 2.1 years.

Performance Share Awards

The vesting of PSAs is contingent upon meeting a cumulative level of earnings per share related performance over a three-year period. The actual issue of shares may range from 0-200% of the target number of PSAs granted, based on the terms of the plan and level of achievement of the related performance target. The grant date fair value of PSAs is based upon the market price of Aon plc ordinary shares at the date of grant. The performance conditions are not considered in the determination of the grant date fair value for these awards. Compensation expense is recognized over the performance period based on management’s estimate of the number of units expected to vest. Management evaluates on a quarterly basis its estimate of the actual number of shares expected to be issued at the end of the programs. The cumulative effect of the change in estimate is recognized in the period of change as an adjustment to Compensation and benefits expense, if necessary. Dividend equivalents are not paid on PSAs.

Information regarding the Company’s target PSAs granted and shares that would be issued at current performance levels for PSAs granted during the years ended December 31, 2017, 2016, and 2015, respectively, is as follows (shares in thousands and dollars in millions, except fair value):



	2017		2016		2015
Target PSAs granted during period	548		750		963
Weighted average fair value per share at date of grant	$	114	$	100	$	96
Number of shares that would be issued based on current performance levels	944		745		1,527
Unamortized expense, based on current performance levels	$	78	$	25	$	—

During 2017, the Company issued approximately 0.9 million shares in connection with performance achievements related to the 2014-2016 Leadership Performance Plan (“LPP”) cycle. During 2016, the Company issued approximately 1.3 million shares in connection with performance achievements related to the 2013-2015 LPP cycle. During 2015, the Company issued approximately 1.6 million shares in connection with performance achievements related to the 2012-2014 LPP cycle.