Stock Plans (Tables)

12 Months Ended

Dec. 31, 2022

Stock Plans

Schedule of stock options activity

	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (thousands)
Balance at December 31, 2021 (1,466,983 shares exercisable)	4,309,201		$	102.19
Granted	622,722		$	90.31
Exercised	(197,184	)	$	30.11
Forfeited/Canceled	(30,316	)	$	125.52
Expired	(1,018	)	$	23.63
Balance at December 31, 2022	4,703,405		$	103.51	6.9	$	26,045
Exercisable at December 31, 2022	1,514,504		$	91.88	4.4	$	23,497
Vested and expected to vest at December 31, 2022	4,207,661		$	95.72	6.0	$	25,584

Schedule of the fair value using the Black-Scholes-Merton option-pricing model

	Year ended December 31,
	2022			2021			2020
Volatility	42.4		%	39.3		%	35.6		%
Risk-free interest rate - weighted average	3.97		%	1.2		%	0.6		%
Risk-free interest rate - range	3.45% to 3.97		%	0.50% to 1.21		%	0.31% to 1.17		%
Dividend yield	—		%	—		%	—		%
Assumed forfeitures	8.0		%	8.0		%	8.0		%
Expected lives	4.6 years			4.6 years			7.1 years
Weighted-average fair value (per option)	$	37.15		$	39.99		$	48.21

Schedule of restricted stock activity

	Number of Shares		Weighted Average Grant Date Fair Value Per Share
Nonvested at December 31, 2021	535,104		$	127.96
Granted	270,124		$	91.47
Vested	(90,986	)	$	39.99
Forfeited	(37,807	)	$	117.01
Nonvested at December 31, 2022	676,435		$	115.36