Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Schedule of stock-based compensation expense, net of forfeitures

For 2020, 2019, and 2018, stock-based compensation expense, net of forfeitures, was recorded as follows (in thousands):

	2020		2019		2018
Equity-classified awards:
Restricted stock	$	2,555	$	2,468	$	2,257
Market based RSUs	1,255		—		—
Performance based RSUs	428		—		—
Director grants	1,060		1,362		1,142
Total equity-classified award expense, net of forfeitures	5,298		3,830		3,399
Liability-classified awards
Market based RSUs	2,498		6,306		2,712
Performance based RSUs	258		1,814		963
Time vested RSUs	633		1,040		357
Dividend equivalent units	675		740		532
Total liability-classified award expense, net of forfeitures	4,064		9,900		4,564
Total stock-based compensation expense, net of forfeitures	$	9,362	$	13,730	$	7,963

Summary of equity and liability classified award activity

The following table summarizes equity-classified award activity for the years ended December 31, 2020, 2019, and 2018 (shares in thousands):

	2020		2019		2018
	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	141	$34.81	148	$33.08	139	$31.72
Granted	173	$44.13	66	$35.64	78	$34.04
Vested	(82)	$34.69	(72)	$34.09	(64)	$31.32
Forfeited	(11)	$41.10	(1)	$34.46	(5)	$32.88
Shares unvested at end of year	221	$41.90	141	$34.81	148	$33.08

The following table summarizes the Company's liability-classified award activity during the years ended December 31, 2020, 2019, and 2018 (shares in thousands):

	2020	2019	2018
	Shares	Shares	Shares
Shares unvested at beginning of the year	316	276	262
Granted	—	136	117
Vested	(172)	(95)	(94)
Forfeited	(9)	(1)	(9)
Shares unvested at end of year	135	316	276

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 2020:

		2020
Volatility	(1)	18.00	%
Risk-free rate	(2)	1.34	%
Stock beta	(3)	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, 2020, 2019, and 2018 (options in thousands):

	2020		2019		2018
	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	67	$23.13	114	$24.00	232	$26.36
Exercised	(37)	$21.28	(42)	$25.59	(114)	$26.40
Forfeited/Expired	(2)	$22.76	(5)	$25.32	(4)	$74.88
Outstanding at end of year	28	$25.55	67	$23.13	114	$24.00