Summary of Significant Accounting Policies - Weighted Average Number of Shares Outstanding Used to Compute Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Net income	$ 29,174	$ 32,461	$ 9,035
Weighted-average number of common shares outstanding
Basic weighted-average common shares outstanding (in shares)	11,676	11,518	11,390
Dilutive potential common shares (in shares)	256	274	269
Diluted weighted-average common shares outstanding (in shares)	11,932	11,792	11,659
Earnings per share
Basic earnings per share (in dollars per share)	$ 2.50	$ 2.82	$ 0.79
Diluted earnings per share (in dollars per share)	$ 2.45	$ 2.75	$ 0.77