Stock-Based Compensation

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Equity-based awards, including restricted stock units ("RSUs"), performance stock units ("PSUs"), stock options and unrestricted shares of common stock, may be granted to officers, employees and directors of the Company pursuant to the Company's Omnibus Incentive and Equity Plan (the "Omnibus Plan"). At March 31, 2024, 375,169 shares of common stock remained available for issuance of the 3,370,000 shares that are authorized for issuance under the Omnibus Plan.

Stock-based compensation expense is summarized as follows:


	Three Months Ended March 31,
(in thousands)	2024		2023
Stock-based compensation expense	$	6,831	$	5,749

Restricted Stock Units

Each RSU entitles the holder to one share of common stock when the restriction expires. RSUs may be time-vested or performance-contingent PSUs that convert into RSUs after performance measurement is complete and generally vest in one to three years. Shares that are issued upon vesting are newly issued shares from the Omnibus Plan and are not issued from treasury stock.

RSU activity, inclusive of PSUs, for the three months ended March 31, 2024 is summarized as follows:


	Number of Shares	Weighted Average Grant Date Fair Value
Outstanding at December 31, 2023	344,717	$	204.48
Granted	108,658	$	235.14
Forfeited	(8,333)	$	261.65
Settled	(103,849)	$	229.92
Outstanding at March 31, 2024	341,193	$	205.10

For the three months ended March 31, 2024 and 2023, a total of 42,588 and 70,716 RSUs, respectively, were withheld by the Company as a result of net share settlements to settle minimum employee tax withholding obligations and for which the Company paid $9.9 million and $12.2 million respectively, in minimum employee tax withholding obligations. These net share settlements had the effect of share repurchases by the Company as they reduced the number of shares that would have otherwise been issued as a result of the vesting.

During the three months ended March 31, 2024 and 2023, the Company granted 26,733 and 44,291 PSUs, respectively, that contain performance-based metrics in addition to a service condition. Compensation expense for PSUs is generally recognized over a three-year service period based upon the value determined using a combination of (i) the intrinsic value method for awards that contain a performance metric that represents a "performance condition" in accordance with ASC 718, Stock Compensation ("ASC 718") and (ii) the Monte Carlo simulation valuation model for awards that contain a "market condition" performance metric under ASC 718. Compensation expense for PSU awards that contain a market condition is fixed at the date of grant and will not be adjusted in future periods based upon the achievement of the market condition. Compensation expense for PSU awards with a performance condition is recorded each period based upon a probability assessment of the expected outcome of the performance metric with a final adjustment upon measurement at the end of the performance period.

As of March 31, 2024, unamortized stock-based compensation expense for unvested RSUs and PSUs was $45.5 million with a weighted-average remaining contractual life of 1.6 years.