Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Schedule of stock-based compensation expense, net of forfeitures

For 2021, 2020, and 2019, stock-based compensation expense, net of forfeitures, was recorded as follows (in thousands):

	2021		2020		2019
Equity-classified awards:
Restricted stock	$	2,677	$	2,555	$	2,468
Market-based RSUs	2,532		1,255		—
Performance-based RSUs	881		428		—
Director grants	890		1,060		1,362
	6,980		5,298		3,830
Liability-classified awards
Market-based RSUs	1,942		2,498		6,306
Performance-based RSUs	456		258		1,814
Service-based RSUs	690		633		1,040
Dividend equivalent units	564		675		740
	3,652		4,064		9,900
Total stock-based compensation expense	$	10,632	$	9,362	$	13,730

Summary of equity and liability classified award activity

The following table summarizes equity-classified award activity for the years ended December 31, 2021, 2020, and 2019 (shares in thousands):

	2021		2020		2019
	Shares	Weighted Average Fair Market Value at Grant	Shares	Weighted Average Fair Market Value at Grant	Shares	Weighted Average Fair Market Value at Grant
Shares unvested at beginning of the year	221	$41.90	141	$34.81	148	$33.08
Granted	248	$35.44	173	$44.13	66	$35.64
Vested	(58)	$37.47	(82)	$34.69	(72)	$34.09
Forfeited	(2)	$39.27	(11)	$41.10	(1)	$34.46
Shares unvested at end of year	409	$38.63	221	$41.90	141	$34.81

The following table summarizes the Company's liability-classified award activity during the years ended December 31, 2021, 2020, and 2019 (shares in thousands):

	2021	2020	2019
	Shares	Shares	Shares
Shares unvested at beginning of the year	135	316	276
Granted	—	—	136
Vested	(92)	(172)	(95)
Forfeited	—	(9)	(1)
Shares unvested at end of year	43	135	316

Summary of valuation assumptions

The Monte Carlo valuation used to determine the grant date fair value of the equity-classified Market-based RSUs included the following assumptions for those RSUs granted in 2021 and 2020:

		2021		2020
Volatility	(1)	37.5	%	18.0	%
Risk-free rate	(2)	0.17	%	1.34	%
Stock beta	(3)	1.04	%	1.04	%

(1) Based on historical volatility over three years using daily stock price.

(2) Reflects the yield on three-year Treasury bonds.

(3) Betas are calculated with up to three years of daily stock price data.

Summary of stock options activity

The following is a summary of stock option activity for the years ended December 31, 2021, 2020, and 2019 (options in thousands):

	2021		2020		2019
	Number of Options	Weighted Average Exercise Price Per Option	Number of Options	Weighted Average Exercise Price Per Option	Number of Options	Weighted Average Exercise Price Per Option
Outstanding at beginning of year	28	$25.55	67	$23.13	114	$24.00
Exercised	(28)	$25.55	(37)	$21.28	(42)	$25.59
Forfeited/expired	—	—	(2)	$22.76	(5)	$25.32
Outstanding at end of year	—	—	28	$25.55	67	$23.13