Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

	2020								2019
	1Q		2Q		3Q		4Q		1Q		2Q		3Q		4Q
Revenue	$	358,238	$	353,987	$	360,315	$	434,335	$	341,254	$	366,717	$	373,918	$	396,636
Operating income	$	16,319	$	22,782	$	28,250	$	21,758	$	21,889	$	22,542	$	28,664	$	28,298
Net income	$	10,612	$	13,656	$	17,871	$	12,820	$	15,318	$	14,611	$	19,630	$	19,379
Earnings per share:
Basic	$	0.56	$	0.73	$	0.95	$	0.68	$	0.81	$	0.78	$	1.04	$	1.03
Diluted	$	0.55	$	0.72	$	0.94	$	0.67	$	0.80	$	0.76	$	1.02	$	1.01
Weighted-average common shares outstanding
(in thousands)
Basic		18,840		18,829		18,853		18,841		18,825		18,805		18,799		18,834
Diluted		19,197		19,020		19,086		19,143		19,263		19,133		19,169		19,234
Cash dividends declared per common share	$	0.14	$	0.14	$	0.14	$	0.14	$	0.14	$	0.14	$	0.14	$	0.14