We maintain a Management Incentive Plan (the “Plan”) that provides various share-based financial methods to compensate our key employees with shares of our common stock or common stock equivalents. Under the Plan, as amended, we have, from time to time, utilized restricted share units, performance share units, restricted shares, and non-statutory stock options to compensate our employees and directors. We currently are utilizing restricted and performance share units.

Our restricted share units have various vesting schedules generally ranging from 3 to 10 years when awarded. These restricted share units do not contain rights to vote or receive dividends until the vesting date. Unvested restricted share units are forfeited if the employee terminates for any reason other than death, disability, or special circumstances as determined by the Compensation Committee. Restricted share units are valued based on the fair value of the award on the grant date, adjusted for dividend estimates based on grant date dividend rates.

Our performance share units vest based on the passage of time (generally 3 to 10 years) and achievement of performance criteria. Performance share units do not contain rights to vote or receive dividends until the vesting date. Unvested performance share units are forfeited if the employee terminates for any reason other than death, disability, or special circumstances as determined by the Compensation Committee. Performance shares are valued based on the fair value of the award on the grant date, adjusted for dividend estimates based on grant date dividend rates.

An employee is allowed to surrender shares of common stock received upon vesting to satisfy tax withholding obligations incident to the vesting of restricted share units and performance share units.

We account for our restricted share units and performance share units in accordance with current accounting standards for share-based payments. These standards require that the cost of all share-based payments to employees be recognized in our Consolidated Financial Statements based on the grant date fair value of those awards. This cost is recognized over the period for which an employee is required to provide service in exchange for the award, subject to the attainment of performance metrics established for performance share units. Share-based compensation expense is recorded in salaries, wages, and employee benefits in our Consolidated Statements of Earnings, along with other compensation expenses to employees. The following table summarizes the components of our share-based compensation program expense (in thousands):

	Years ended December 31,
	2019		2018		2017
Restricted share units
Pretax compensation expense	$	38,632	$	32,797	$	28,679
Tax benefit		9,337		7,740		(4,385	)
Restricted share units, net of tax	$	29,295	$	25,057	$	33,064
Performance share units
Pretax compensation expense	$	14,692	$	14,572	$	9,612
Tax benefit		3,551		3,439		(1,470	)
Performance share awards, net of tax	$	11,141	$	11,133	$	11,082

A summary of our restricted share units and performance share units is as follows:

Restricted Share Units	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2016		1,502,656		$	71.16
Granted		158,319			90.06
Vested		(380,702	)		67.29
Forfeited		(37,745	)		75.13
Unvested at December 31, 2017		1,242,528		$	74.71
Granted		370,669			119.82
Vested		(337,512	)		79.02
Forfeited		(29,850	)		83.69
Unvested at December 31, 2018		1,245,835		$	86.80
Granted		440,255			99.60
Vested		(341,218	)		85.61
Forfeited		(31,454	)		93.91
Unvested at December 31, 2019		1,313,418		$	91.22

Performance Share Units	Number of Shares			Weighted Average Grant Date Fair Value
Unvested at December 31, 2016		484,054		$	70.58
Granted		-			-
Vested		(155,867	)		68.27
Forfeited		-			-
Unvested at December 31, 2017		328,187		$	71.68
Granted		150,763			122.57
Vested		(118,438	)		69.29
Forfeited		-			-
Unvested at December 31, 2018		360,512		$	93.74
Granted		142,156			98.58
Vested		(127,140	)		93.46
Forfeited		-			-
Unvested at December 31, 2019		375,528		$	95.67

At December 31, 2019, we had $61.3 million and $13.0 million of total unrecognized compensation expense related to restricted share units and performance share units, respectively, that is expected to be recognized on a straight-line basis over the remaining weighted average vesting period of approximately 3.2 years for restricted share units and 2.2 years for performance share units.

The aggregate intrinsic value of restricted and performance share units vested during the years ended December 31, 2019, 2018, and 2017, was $47.0 million, $55.1 million, and $49.3 million, respectively. The aggregate intrinsic value of unvested restricted and performance share units was $197.2 million at December 31, 2019. The total fair value of shares vested for restricted and performance share units during the years ended December 31, 2019, 2018, and 2017, was $41.1 million, $35.0 million, and $36.4 million, respectively.