Stock-Based Compensation - Share Appreciation Rights (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Stock options outstanding (in shares)	222,273	291,779	319,086	617,446
Stock options outstanding (in dollars per share)	$ 15.44	$ 14.05	$ 13.53	$ 10.53
SARS outstanding (in shares)	0	32,282	42,152	42,152
SARs outstanding (in dollars per share)	$ 0	$ 15.40	$ 14.14	$ 14.14
Stock options granted (in shares)	(30,401)	(11,055)	(14,310)
Stock options granted (in dollars per share)	$ 5.57	$ 5.57	$ 7.91
SARs granted (in shares)	0	0	0
SARs granted (in dollars per share)	$ 0	$ 0	$ 0
Stock options exercised (in shares)	(39,105)	(11,519)	(159,069)
Stock options exercised (in dollars per share)	$ 12.77	$ 9.31	$ 3.35
SARs exercised (in shares)	0	0	0
SARs exercised (in dollars per share)	$ 0	$ 0	$ 0
Stock options canceled/forfeited (in shares)		(4,733)	(153,601)
Stock options canceled/forfeited (in dollars per share)		$ 10.00	$ 11.48
SARs canceled/forfeited (in shares)		(9,870)	0
SARs canceled/forfeited (in dollars per share)		$ 10.00	$ 0
Stock options expired (in shares)	0
Stock options expired (in dollars per share)	$ 0
SARs expired (in shares)	(32,282)
SARS expired (in dollars per share)	$ 15.40