Earnings per Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share, Basic and Diluted [Abstract]
Net income	$ 20,911	$ 18,119	$ 74,389	$ 21,042
Net income allocated to unvested restricted stock awards	0	(23)	(28)	(29)
Net income allocated to common shares	$ 20,911	$ 18,096	$ 74,361	$ 21,013
Weighted average shares outstanding	29,420	29,227	29,380	29,233
Average unvested restricted stock awards	0	(38)	(10)	(47)
Denominator for basic earnings per share—weighted-average shares outstanding	29,420	29,189	29,370	29,186
Effect of dilutive securities—employee stock options and restricted stock units	142	28	143	32
Denominator for diluted earnings per share—adjusted weighted-average shares outstanding	29,562	29,217	29,513	29,218
Basic earnings per share	$ 0.71	$ 0.62	$ 2.53	$ 0.72
Diluted earnings per share	$ 0.71	$ 0.62	$ 2.52	$ 0.72
Average antidilutive options and restricted stock units excluded from computation of diluted earnings per share	286	526	289	509