Significant Accounting Policies - Earnings (Loss) Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Denominator:
Denominator for basic earnings (loss) per share (in shares)	22,585,515	22,515,161	22,901,511
Effect of dilutive securities:
Supplemental executive retirement plan (in shares)	40,859	48,047	0
Denominator for diluted earnings (loss) per share (in shares)	22,877,743	22,674,182	22,901,511
Restricted Stock
Effect of dilutive securities:
Unvested stock units (in shares)	185,965	110,974	0
Performance Shares
Effect of dilutive securities:
Unvested stock units (in shares)	65,404	0	0