Share-based compensation (Notes)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock plan

For the purpose of attracting and retaining the highest-quality personnel, providing for additional incentives, and promoting the success of our Company, we have historically issued two forms of share-based compensation under our equity incentive plan: (i) options to purchase common stock and (ii) restricted stock. We have not granted any options since 2002. Each restricted share issued reduced our share reserve by three shares (3:1 ratio) prior to March 23, 2018, and by one share (1:1 ratio) on and after March 23, 2018. As of December 31, 2021, there were 2,556,301 shares reserved for the granting of future options and stock awards under the equity incentive plan.

In addition, our stock plan permits us to issue share awards to our employees, non-employees, and non-employee directors. A share award is an award of common stock that (i) may be fully vested upon issuance or (ii) may be subject to the risk of forfeiture under Section 83 of the Code. Shares issued generally vest over a four-year period from the date of issuance, and the sale of the shares is restricted prior to the date of vesting. Certain time-based restricted share awards are also subject to an additional one-year holding period after vesting. The unearned portion of time-based share awards is amortized as stock compensation expense on a straight-line basis over the vesting period. Certain restricted share awards are subject to vesting based upon the satisfaction of levels of performance and market conditions. Failure to satisfy the threshold performance conditions will result in the forfeiture of shares. Forfeiture of share awards with time-based or performance-based restrictions results in a reversal of previously recognized share-based compensation expense. Forfeiture of share awards with market-based restrictions does not result in a reversal of previously recognized share-based compensation expense.

The following is a summary of the stock awards activity under our equity incentive plan and related information for the years ended December 31, 2021, 2020, and 2019:


			Number of Share Awards		Weighted-Average Grant Date Fair Value Per Share
Outstanding at December 31, 2018			1,712,376		$		105.22
Granted			768,625		$		134.70
Vested			(666,836)		$		96.77
Forfeited			(14,480)		$		119.88
Outstanding at December 31, 2019			1,799,685		$		119.59
Granted			753,473		$		147.71
Vested			(688,599)		$		115.57
Forfeited			(39,279)		$		117.76
Outstanding at December 31, 2020			1,825,280		$		132.95
Granted			740,920		$		174.32
Vested			(709,737)		$		131.54
Forfeited			(33,003)		$		99.55
Outstanding at December 31, 2021			1,823,460		$		150.89

	Year Ended December 31,
(In thousands)	2021		2020		2019
Total grant date fair value of stock awards vested	$	93,359	$	79,578	$	64,530
Total gross compensation recognized for stock awards	$	94,748	$	80,651	$	68,036
Capitalized stock compensation	$	46,079	$	37,149	$	24,396

Certain restricted stock awards granted during each year from 2018 to 2021 are subject to performance and market conditions. The grant date fair value of these awards is determined using a Monte Carlo simulation pricing model using the following assumptions for 2021, 2020, and 2019, respectively: (i) expected term of 3.0 years, 3.0 years, and 3.0 years (equal to the remaining performance measurement period at the grant date), (ii) volatility of 29.0%, 17.0%, and 18.0% (approximating a blended average of implied and historical volatilities), (iii) dividend yield of 2.8%, 2.8%, and 3.2%, and (iv) risk-free rate of 0.23%, 1.63%, and 2.60%.

As of December 31, 2021, there was $222.3 million of unrecognized compensation related to unvested share awards under the equity incentive plan, which is expected to be recognized over the next four years and has a weighted-average vesting period of approximately 19 months.