Earnings Per Share (Computation of Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income	$ 31,218	$ 13,259
Denominator:
Weighted-average shares outstanding - basic (in shares)	18,712,000	18,669,000
Effect of dilutive shares (in shares)	62,000	22,000
Weighted-average shares outstanding - dilutive (in shares)	18,774,000	18,691,000
Basic earnings per share (in dollars per share)	$ 1.67	$ 0.71
Diluted earnings per share (in dollars per share)	$ 1.66	$ 0.71
Anti-dilutive shares excluded (in shares)	44,792	127,106