Stock-based Compensation

12 Months Ended

Dec. 31, 2021

Share-Based Payment Arrangement, Noncash Expense [Abstract]

Stock Compensation Plans

Pursuant to stockholder approved plans, the Company has granted stock-based awards to certain employees, consultants or non-employee directors of the Company and its subsidiaries or affiliates. Following the stockholder approval of the 2022 Long-Term Incentive Plan ("2022 LTIP"), no further awards can be made under the 2013 Long-Term Incentive Plan ("2013 LTIP"). As of December 31, 2022, the Company had approximately 3 million shares available for issuance under existing awards pursuant to the 2013 LTIP and approximately 13 million shares available for issuance under existing and future awards pursuant to the 2022 LTIP. Of the shares remaining available for future issuance, approximately 2 million shares may be issued pursuant to outstanding RSUs granted under the 2013 LTIP.

Restricted Stock Units

The Company issues RSUs to certain executives and employees. Each RSU represents a contingent right to receive one share of the Company's common stock subject to satisfaction of the applicable vesting terms. The RSUs granted to certain executives and employees include (1) annual performance awards that generally include provisions for forfeiture by the employee if certain market performance of the Company's common stock (as further described below) is not achieved, (2) new hire or promotional awards that generally contain only service-based vesting conditions and (3) other awards related to specific business initiatives or compensation objectives including retention and merger integration. Generally, such awards vest over periods of approximately three years.

The following is a summary of the RSU activity during the year ended December 31, 2022.


			RSUs
			(In millions)
Outstanding at the beginning of year			2
Granted			1
Vested			(1)
Forfeited			—
Outstanding at end of year			2

The Company granted approximately one million RSUs to its executives and certain other employees for each of the years ended December 31, 2022, 2021 and 2020. The weighted-average grant-date fair value per share of the grants for the years ended December 31, 2022, 2021 and 2020 was $146.52, $155.01 and $160.78 per share, respectively. The weighted-average requisite service period for the RSUs granted during 2022 was approximately 2.3 years.

Of the approximately one million RSUs granted during the year ended December 31, 2022, (1) approximately 0.7 million RSUs were subject to time-based vesting conditions, vesting over a three-year period and (2) approximately 0.4 million RSUs were granted to the Company's executives and certain other employees and may vest on the third anniversary of the grant date based upon (a) the Company's total stockholder returns (defined as share price appreciation plus the value of dividends paid during the performance period) and (b) the Company's total stockholder return compared to that of the companies in the Standard & Poor's 500 Index. Certain RSU agreements contain provisions that result in forfeiture by the employee of any unvested shares in the event that the Company's common stock does not achieve certain performance targets. To the extent that the requisite service is rendered, compensation cost for accounting purposes is not reversed; rather, it is recognized regardless of whether or not the market performance target is achieved.

The following table summarizes the assumptions used in the Monte Carlo simulation to determine the grant-date fair value for the RSUs with market conditions granted during the years ended December 31, 2022, 2021 and 2020.


	Years Ended December 31,
	2022		2021		2020
Risk-free rate	1.7	%	0.2	%	1.4	%
Expected volatility	31	%	30	%	19	%
Expected dividend rate	3.0	%	3.4	%	3.5	%

The Company recognized aggregate stock-based compensation expense related to RSUs of $134 million, $110 million and $111 million for the years ended December 31, 2022, 2021 and 2020, respectively. The aggregate unrecognized compensation (net of estimated forfeitures) related to RSUs at December 31, 2022 is $69 million and is estimated to be recognized over a weighted-average period of less than one year.

The following table is a summary of the RSUs vested during the years ended December 31, 2022, 2021 and 2020.


Years Ended December 31,	Total Shares Vested	Fair Value on Vesting Date
	(In millions of shares)
2022	1	$	187
2021	1	199
2020	1	220

Stock-based Compensation Expense

The following table discloses the components of stock-based compensation expense.


	Years Ended December 31,
	2022		2021		2020
Stock-based compensation expense:
Site rental costs of operations	$	18	$	14	$	16
Services and other costs of operations	10		8		8
Selling, general and administrative expenses	128		109		109
Total stock-based compensation expense	$	156	$	131	$	133