Stock-Based Compensation - Schedule of SAR Activity (Details) - SARs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Shares
Outstanding, beginning balance (in shares)	130,070	138,020
Granted (in shares)	50,000	9,000
Exercised (in shares)	0	0
Forfeited (in shares)	0	(7,334)
Expired (in shares)	(4,500)	(9,616)
Outstanding, ending balance (in shares)	175,570	130,070	138,020
Exercisable (in shares)	119,569	86,736
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 9.41	$ 9.66
Granted (in dollars per share)	4.83	7.30
Exercised (in dollars per share)	0	0
Forfeited (in dollars per share)	0	9.81
Expired (in dollars per share)	11.25	10.70
Outstanding, ending balance (in dollars per share)	8.06	9.41	$ 9.66
Exercisable (in dollars per share)	$ 9.00	$ 10.33
Weighted-Average Remaining Contractual Term (years)
Outstanding (in years)	7 years 14 days	7 years 2 months 15 days	8 years 18 days
Exercisable (in years)	6 years 5 months 15 days	5 years 10 months 28 days
Aggregate Intrinsic Value (in thousands)
Outstanding	$ 0	$ 11	$ 89
Exercisable	$ 0	$ 5