Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of Share-based Compensation, Restricted Stock Units Award Activity

RSU activity for the nine months ended September 30, 2020 is as follows:

	Number of Shares	Weighted-Average Grant-Date Fair Value
(in thousands, except weighted-average fair value prices)
Unvested RSUs outstanding at December 31, 2019	1,032	$	39.84
RSUs granted	777	$	37.10
RSUs vested	(524)	$	40.51
RSUs forfeited	(47)	$	36.53
Unvested RSUs outstanding at September 30, 2020	1,238	$	37.98

Schedule of Share-based Payment Award, Performance-Based Units, Valuation Assumptions

market-based vesting conditions, we also use the Monte-Carlo simulation with the following weighted-average assumptions:

	For the Nine Months Ended September 30,
	2020		2019
Expected dividend yield (1)	—	%	—	%
Risk-free interest rate (2)	0.60	%	2.44	%
Expected volatility (3)	32.53	%	28.24	%
Average total stockholder return (3)	(21.47)	%	17.15	%
(1) Since PBRSU participants are credited with dividend equivalent shares when dividends are paid, 0.00% was used in the Monte-Carlo simulation which is mathematically equivalent to paying dividend equivalents upon vesting. Please see Note 1 - Basis for Condensed Consolidated Financial Statements for further information regarding dividends. (2) The risk-free interest rate for the periods within the contractual term of the PBRSUs is based on the US Treasury yield curve in effect at the time of the grant. (3) The expected volatility and average total stockholder return are measures of the amount by which a stock price has fluctuated or is expected to fluctuate based primarily on our and our peers' historical data.

Schedule of Other Share-based Compensation, Activity

PBRSU activity for the nine months ended September 30, 2020 is as follows:

	Number of Shares	Weighted-Average Grant-Date Fair Value
(in thousands, except weighted-average fair value prices)
Unvested PBRSUs outstanding at December 31, 2019	636	$	42.62
PBRSUs granted	321	$	40.64
PBRSUs vested	(184)	$	39.50
PBRSUs forfeited	(29)	$	44.77
Unvested PBRSUs outstanding at September 30, 2020	744	$	42.58

Schedule of Share-based Compensation, Stock Options, Activity

Option activity for the nine months ended September 30, 2020 is as follows:

(in thousands, except weighted-average price)	Number of Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term	Aggregate Intrinsic Value
Options outstanding at December 31, 2019	479	$	19.59
Options exercised	(82)	$	18.34
Options outstanding at September 30, 2020	397	$	19.84	1.9	$	19,024

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The following table sets forth the share-based compensation expense recognized for the three and nine months ended September 30, 2020 and 2019:

	For the Three Months Ended				For the Nine Months Ended
	September 30,				September 30,
(in thousands)	2020		2019		2020		2019
RSUs	$	6,378	$	4,521	$	17,446	$	17,063
PBRSUs	5,468		3,893		14,264		7,390
Stock options	—		—		—		—
Employee stock purchase plan	700		392		2,188		1,565
	$	12,546	$	8,806	$	33,898	$	26,018