Stock-Based Compensation (Tables)

Stock-based compensation expense under the Company’s plans was as follows:


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2020		2019		2020		2019
Stock-based compensation expense	$	15,729	$	13,169	$	42,500	$	39,467
Tax effect on stock-based compensation expense	(4,011)		(3,438)		(10,837)		(10,305)
Net effect on income	$	11,718	$	9,731	$	31,663	$	29,162

The following weighted average assumptions were used to value options granted during the periods indicated:


	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2020			2019			2020			2019
Grant date fair value of options	$	—		$	—		$	—		$	21.55
Volatility	—		%	—		%	—		%	40.0		%
Risk-free interest rate	—		%	—		%	—		%	2.5		%
Dividend yield	—		%	—		%	—		%	—		%
Expected term (in years)	0.0			0.0			0.0			6.5

The following table summarizes option activity under the Company’s plans:

The following is a summary of the activity for unvested restricted stock units and performance stock units granted under the Company’s plans:


	RSUs			PSUs
	Number of Shares	Weighted- Average Grant Date Fair Value per Share		Number of Shares	Weighted- Average Grant Date Fair Value per Share
Outstanding as of December 31, 2019	1,318,870	$	58.88	254,118	$	67.96
Granted	956,494	74.55		67,793	81.42
Vested	(677,129)	57.51		—	—
Forfeited	(120,421)	61.04		(33,010)	64.70
Outstanding as of September 30, 2020	1,477,814	69.48		288,901	71.49