Share and Unit-based Plans

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Share and Unit-based Plans:

The Company has established share and unit-based compensation plans for the purpose of attracting and retaining executive officers, directors and key employees.

2003 Equity Incentive Plan:

The 2003 Equity Incentive Plan ("2003 Plan") authorizes the grant of stock awards, stock options, stock appreciation rights, stock units, stock bonuses, performance-based awards, dividend equivalent rights and OP Units or other convertible or exchangeable units. As of December 31, 2023, stock awards, stock units, LTIP Units (as defined below), stock appreciation rights ("SARs") and stock options have been granted under the 2003 Plan. All stock options or other rights to acquire common stock granted under the 2003 Plan have a term of 10 years or less. These awards were generally granted based on the performance of the Company and the employees. None of the awards have performance requirements other than a service condition of continued employment unless otherwise provided. All awards are subject to restrictions determined by the Company's compensation committee. The aggregate number of shares of common stock that may be issued under the 2003 Plan is 26,112,331 shares. As of December 31, 2023, there were 7,678,580 shares available for issuance under the 2003 Plan.

Stock Units:

The stock units represent the right to receive upon vesting one share of the Company's common stock for one stock unit. The value of the stock units was determined by the market price of the Company's common stock on the date of the grant. The following table summarizes the activity of non-vested stock units during the years ended December 31, 2023, 2022 and 2021:


	2023			2022			2021
	Units	Weighted Average Grant Date Fair Value		Units	Weighted Average Grant Date Fair Value		Units	Weighted Average Grant Date Fair Value
Balance at beginning of year	295,054	$	14.58	266,505	$	19.05	309,845	$	21.47
Granted	251,738	10.92		209,146	13.43		169,112	14.61
Vested	(262,745)	14.08		(180,597)	19.84		(211,465)	19.03
Forfeited	—	—		—	—		(987)	22.12
Balance at end of year	284,047	$	11.79	295,054	$	14.58	266,505	$	19.05

19. Share and Unit-based Plans: (Continued)

Long-Term Incentive Plan Units:

Under the Long-Term Incentive Plan ("LTIP"), each award recipient is issued a form of operating partnership units ("LTIP Units") in the Operating Partnership or form of restricted stock units (together with the LTIP Units, the "LTI Units"). Upon the occurrence of specified events and subject to the satisfaction of applicable vesting conditions, LTIP Units (after conversion into OP Units) are ultimately redeemable for common stock of the Company, or cash at the Company's option, on a one-unit for one-share basis. LTI Units receive cash dividends based on the dividend amount paid on the common stock of the Company. The LTIP may include market-indexed awards, performance-based awards and service-based awards.

The market-indexed LTI Units vest over the service period of the award based on the percentile ranking of the Company in terms of total return to stockholders (the "Total Return") per share of common stock relative to the Total Return of a group of peer REITs, as measured at the end of the measurement period. The performance-based LTI Units vest over a specified period based on the Company's operational performance over that period.

The fair value of the service-based LTI Units was determined by the market price of the Company's common stock on the date of the grant. The fair value of the market-indexed LTI Units and performance-based LTI Units are estimated on the date of grant using a Monte Carlo Simulation model. The stock price of the Company, along with the stock prices of the group of peer REITs (for market-indexed awards), is assumed to follow the Multivariate Geometric Brownian Motion Process. Multivariate Geometric Brownian Motion is a common assumption when modeling in financial markets, as it allows the modeled quantity (in this case, the stock price) to vary randomly from its current value and take any value greater than zero. The volatilities of the returns on the share price of the Company and the peer group REITs were estimated based on a look-back period. The expected growth rate of the stock prices over the "derived service period" is determined with consideration of the risk free rate as of the grant date.

The Company has granted the following LTI units during the years ended December 31, 2023, 2022 and 2021:


Grant Date	Units	Type	Fair Value per LTI Unit		Vest Date
1/1/2021	576,378	Service-based	$	10.67	12/31/2023
1/1/2021	1,005,073	Performance-based	$	9.85	12/31/2023
	1,581,451

1/1/2022	376,153	Service-based	$	17.28	12/31/2024
1/1/2022	716,545	Performance-based	$	15.77	12/31/2024
	1,092,698

1/1/2023	577,255	Service-based	$	11.26	12/31/2025
1/1/2023	1,030,077	Performance-based	$	10.97	12/31/2025
	1,607,332

19. Share and Unit-based Plans: (Continued)

The fair value of the market-indexed LTI Units and performance-based LTI Units (Level 3) were estimated on the date of grant using a Monte Carlo Simulation model that based on the following assumptions:


Grant Date	Risk Free Interest Rate		Expected Volatility
1/1/2021	0.17	%	62.82	%
1/1/2022	0.97	%	70.83	%
1/1/2023	4.21	%	74.23	%

The following table summarizes the activity of the non-vested LTI Units during the years ended December 31, 2023, 2022 and 2021:


	2023			2022			2021
	Units	Weighted Average Grant Date Fair Value		Units	Weighted Average Grant Date Fair Value		Units	Weighted Average Grant Date Fair Value
Balance at beginning of year	2,215,167	$	12.90	1,837,691	$	14.14	784,052	$	28.11
Granted	1,607,332	11.07		1,092,698	16.29		1,581,451	10.15
Vested	(1,378,528)	10.94		(386,828)	15.86		(286,373)	17.62
Forfeited	(187,124)	12.15		(328,394)	27.64		(241,439)	29.25
Balance at end of year	2,256,847	$	12.86	2,215,167	$	12.90	1,837,691	$	14.14

Stock Options:

The following table summarizes the activity of vested stock options for the years ended December 31, 2023, 2022 and 2021:


	2023			2022			2021
	Options	Weighted Average Exercise Price		Options	Weighted Average Exercise Price		Options	Weighted Average Exercise Price
Balance at beginning of year	26,371	$	54.56	37,515	$	54.34	37,515	$	54.34
Granted	—	—		—	—		—	—

Forfeited	—	$	—	(11,144)	53.82		—	—
Balance at end of year	26,371	$	54.56	26,371	$	54.56	37,515	$	54.34

19. Share and Unit-based Plans: (Continued)

Directors' Phantom Stock Plan:

The Directors' Phantom Stock Plan offers non-employee members of the board of directors ("Directors") the opportunity to defer their cash compensation and to receive that compensation in common stock rather than in cash after termination of service or a predetermined period. Compensation generally includes the annual retainers payable by the Company to the Directors. Deferred amounts are generally credited as units of phantom stock at the beginning of each three-year deferral period by dividing the present value of the deferred compensation by the average fair market value of the Company's common stock at the date of award. Compensation expense related to the phantom stock awards was determined by the amortization of the value of the stock units on a straight-line basis over the applicable service period. The stock units (including dividend equivalents) vest as the Directors' services (to which the fees relate) are rendered. Vested phantom stock units are ultimately paid out in common stock on a one-unit for one-share basis. To the extent elected by a Director, stock units receive dividend equivalents in the form of additional stock units based on the dividend amount paid on the common stock. The aggregate number of phantom stock units that may be granted under the Directors' Phantom Stock Plan is 650,000. As of December 31, 2023, there were 174,576 stock units available for grant under the Directors' Phantom Stock Plan.

The following table summarizes the activity of the non-vested phantom stock units for the years ended December 31, 2023, 2022 and 2021:


	2023			2022			2021
	Stock Units	Weighted Average Grant Date Fair Value		Stock Units	Weighted Average Grant Date Fair Value		Stock Units	Weighted Average Grant Date Fair Value
Balance at beginning of year	34,039	$	14.19	—	$	—	4,662	$	35.35
Granted	6,513	11.48		61,420	14.35		17,554	12.09
Vested	(23,509)	13.44		(27,381)	14.55		(22,216)	16.97

Balance at end of year	17,043	$	14.19	34,039	$	14.19	—	$	—

Employee Stock Purchase Plan ("ESPP"):

The ESPP authorizes eligible employees to purchase the Company's common stock through voluntary payroll deductions made during periodic offering periods. Under the ESPP, common stock is purchased at a 15% discount from the lesser of the fair value of common stock at the beginning and end of the offering period. A maximum of 1,291,117 shares of common stock is available for purchase under the ESPP. The number of shares available for future purchase under the plan at December 31, 2023 was 82,873.

Compensation:

The following summarizes the compensation cost under the share and unit-based plans for the years ended December 31, 2023, 2022 and 2021:


	2023		2022		2021
Stock units	$	3,150	$	3,110	$	3,173
LTI units	12,599		18,611		14,448

Phantom stock units	316		398		377
	$	16,065	$	22,119	$	17,998

19. Share and Unit-based Plans: (Continued)

The Company capitalized share and unit-based compensation costs of $2,899, $4,481 and $3,725 for the years ended December 31, 2023, 2022 and 2021, respectively.

The fair value of the stock units that vested during the years ended December 31, 2023, 2022 and 2021 was $2,736, $2,349 and $3,408, respectively. Unrecognized compensation costs of share and unit-based plans at December 31, 2023 consisted of $3,087 from LTI Units and $1,858 from stock units.