Earnings Per Share (Computation of Basic and Diluted) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income	$ 13,259	$ 28,399
Denominator:
Weighted-average shares outstanding - basic (in shares)	18,669,000	18,557,000
Effect of dilutive shares (in shares)	22,000	135,000
Weighted-average shares outstanding - dilutive (in shares)	18,691,000	18,692,000
Basic earnings per share (in dollars per share)	$ 0.71	$ 1.53
Diluted earnings per share (in dollars per share)	$ 0.71	$ 1.52
Anti-dilutive shares excluded (in shares)	127,106	23,081