STOCK-BASED EMPLOYEE COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Activity of unvested restricted stock units

The following table summarizes the activity of restricted stock units for employees and non-employee directors during the three months ended March 31, 2020: 

Restricted Stock Units	Shares		Weighted-average Grant-date Fair Value Per Share
Unvested at December 31, 2019	256,745			$	1,801
Granted	152,832			$	1,732
Vested	(109,595	)		$	1,808
Forfeited	(5,971	)		$	1,805
Unvested at March 31, 2020	294,011			$	1,762

Activity of unvested performance share units

The following table summarizes the activity of performance share units for employees during the three months ended March 31, 2020:

Performance Share Units	Shares		Weighted-average Grant-date Fair Value Per Share
Unvested at December 31, 2019	216,083			$	1,835
Vested	(80,266	)		$	1,737
Performance Shares Adjustment *	(58,427	)		$	1,957
Forfeited	(2,989	)		$	1,834
Unvested at March 31, 2020	74,401			$	1,841

Estimated vesting of performance share units granted [Table Text Block]

The following table summarizes the estimated vesting, as of March 31, 2020, of performance share units granted in 2019 and 2018, net of forfeiture and vesting since the respective grant dates:

Performance Share Units, by grant year	2019	2018
Shares probable to be issued	45,361	29,040
Shares not subject to the achievement of minimum performance thresholds	45,361	28,647
Shares that could be issued if maximum performance thresholds are met	117,558	79,914

Activity of outstanding stock options

All outstanding employee stock options were assumed in acquisitions, and generally have a term of 10 years from the grant date. The following table summarizes the activity for stock options during the three months ended March 31, 2020: 

Employee Stock Options	Number of Shares		Weighted-average Exercise Price			Aggregate  Intrinsic Value (in millions)			Weighted-average Remaining Contractual Term (in years)
Balance, December 31, 2019	15,122			$	484		$	24	2.6
Exercised	(100	)		$	334
Balance, March 31, 2020	15,022			$	485		$	13	2.4
Vested and exercisable at March 31, 2020	15,022			$	485		$	13	2.4