STOCK-BASED COMPENSATION (Tables)

6 Months Ended

Jun. 30, 2021

STOCK-BASED COMPENSATION

Schedule of weighted-average assumptions used to estimate the fair value of options granted

	Three-Months Ended June 30,			Six-Months Ended June 30,
	2021		2020*	2021		2020
Dividend yield	0.0	%	—	0.0	%	0.0	%
Expected volatility	29.0	%	—	28.9	%	30.5	%
Risk-free interest rate	0.9	%	—	0.8	%	0.7	%
Expected term	5.9	years	—	5.8	years	5.8	years

Summary of activities with respect to its stock option plans

				Weighted-
		Weighted-		Average
		Average		Remaining
	Number of	Exercise		Contractual	Aggregate
	Shares (in	Price Per		Term (in	Intrinsic
Options	thousands)	Share		years)	Value
Outstanding at January 1, 2021	13,973	$	44.93	5.7	$	664,432
Granted 01/01/21 - 03/31/21	1,015	$	88.95
Granted 04/01/21 - 06/30/21	13	$	91.36
Exercised	(570)	$	42.95
Cancelled or forfeited	(57)	$	61.56
Outstanding at June 30, 2021	14,374	$	48.09	5.6	$	621,788
Vested and expected to vest in the future at June 30, 2021	14,058	$	47.61	5.5	$	614,822
Exercisable at June 30, 2021	9,682	$	40.31	4.5	$	494,110

Summary of activities with respect to non-vested restricted stock units

		Weighted
	Number of	Average
	Shares (in	Grant-Date
	thousands)	Fair Value
Non-vested at January 1, 2021	947	$	60.52
Granted 01/01/21 - 03/31/211	304	$	86.28
Granted 04/01/21 - 06/30/21	14	$	92.14
Vested	(344)	$	62.27
Forfeited/cancelled	(4)	$	60.15
Non-vested at June 30, 2021	917	$	68.89

¹The grant activity for performance share units is recorded based on the target performance level earning 100% of target performance share units. The actual number of performance share units earned could range from 0% to 200% of target depending on the achievement of pre-established performance goals.