STOCK-BASED COMPENSATION (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock-Based Compensation Expense Included in Consolidated Statements of Operations

(in thousands)	2021		2020		2019
Cost of revenue	$	21,822	$	20,796	$	18,822
Selling and marketing	54,182		46,283		32,665
Research and development	25,413		22,885		18,938
General and administrative	14,530		13,104		10,484
	$	115,947	$	103,068	$	80,909
Income tax benefit	$	(23,410)	$	(20,464)	$	(16,392)

Schedule of Compensating Balances

(in thousands)	2021
Compensation expense from 2006 ESPP	$	1,860

Weighted-Average Assumptions Used in Black-Scholes Option Valuation Model

The following table summarizes the Company’s fair value assumptions for stock options:

	2021			2020			2019
Weighted-average grant-date fair value	$	37.74		$	24.16		$	19.10
Assumptions used in the Black-Scholes option-pricing model:
Expected annual volatility (1)	35		%	31 %			32		%
Expected term in years (2)	4.4			4.5			4.5
Risk-free interest rate (3)	0.6		%	0.7		%	2.4		%
Expected annual dividend yield (4)	0.2		%	0.2		%	0.3		%

(1) The expected annual volatility for each grant is determined based on the average of historic daily price changes of the Company’s common stock over a period, which approximates the expected option term.

(2) The expected option term for each grant is determined based on the historical exercise behavior of employees and post-vesting employment termination behavior.

(3) The risk-free interest rate is based on the yield of U.S. Treasury securities with a commensurate maturity with the expected option term at the time of grant.

(4) The expected annual dividend yield is based on the weighted-average dividend yield assumptions used for options granted during the applicable period.

Combined Stock Option Activity

The following table summarizes the combined stock option activity under the Company’s stock option plans for 2021:

	Shares (in thousands)	Weighted-average Exercise Price		Weighted-average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Options outstanding as of January 1, 2021	7,391	$	59.88
Granted	1,574	129.71
Exercised	(1,170)	47.93
Forfeited	(606)	85.69
Options outstanding as of December 31, 2021	7,189	$	74.94
Vested and expected to vest as of December 31, 2021	6,176	$	71.97	6.7	$	267,722
Exercisable as of December 31, 2021	3,398	$	50.06	5.4	$	210,796

Combined Restricted Stock Units Activity

The following table summarizes the combined RSU activity for all grants, including the CICP, under the 2004 Plan for 2021:

	Shares (in thousands)	Weighted- Average Grant-Date Fair Value		Aggregate Intrinsic Value (in thousands)
Nonvested as of January 1, 2021	2,462	$	74.78
Granted	945	129.03
Vested	(972)	70.19
Forfeited	(381)	88.01
Nonvested as of December 31, 2021	2,054	$	99.36	$	229,643
Expected to vest as of December 31, 2021	1,523	$	101.32	$	170,357