Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Assumptions Used to Determine Fair Value of Stock Options Granted

The assumptions used to determine the fair value of the stock options granted during the three months ended March 31, 2021 and 2020 were as follows:

	Three Months Ended March 31,
	2021			2020
Weighted-average fair value options granted	$	31.02		$	19.67
Average risk-free interest rate		0.33	%		1.44	%
Expected stock price volatility		55.9	%		48.3	%
Dividend yield	None			None
Expected stock option life (years)		4.00			4.00

Summary of Stock Option Activity

Stock option awards as of December 31, 2020 and March 31, 2021, and changes during the three months ended March 31, 2021, were as follows:

	Options			Weighted-Average Exercise Price		Aggregate Intrinsic Value (thousands)		Weighted-Average Exercise Term (years)
Outstanding at December 31, 2020		2,511,570		$	41.58	$	88,030		5.80
Granted		16,841			72.54
Forfeited		(2,433	)		26.34
Exercised		(34,204	)		32.24
Outstanding at March 31, 2021		2,491,774			41.93		59,508		5.60
Vested and expected to vest at March 31, 2021		2,452,818			41.60		59,267		5.55
Exercisable at March 31, 2021		2,065,269		$	36.98	$	57,112		5.07

Non-vested Restricted Stock Units

Non-vested restricted stock units as of December 31, 2020 and March 31, 2021, and changes during the three months ended March 31, 2021 were as follows:

	Restricted Stock Units
	Shares			Weighted-Average Grant Date Fair Value
Outstanding at December 31, 2020		3,088,736		$	61.47
Granted		1,456,877			72.56
Forfeited		(156,491	)		63.93
Vested		(347,836	)		61.71
Outstanding at March 31, 2021		4,041,286		$	65.35