Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue	$ 133,277	$ 127,982	$ 119,686
Insurance recoveries	533
Operating expenses:
Direct	49,187	46,435	47,577
Selling, general and administrative	34,441	32,973	31,371
Depreciation, amortization and impairment	7,505	5,539	5,463
Total operating expenses	91,133	84,947	84,411
Operating income	42,677	43,035	35,275
Other income (expense):
Interest income	18	37	62
Interest expense	(1,813)	(2,091)	(1,513)
Other, net	585	(462)	885
Total other income (expense)	(1,210)	(2,516)	(566)
Income before income taxes	41,467	40,519	34,709
Provision for income taxes	4,207	8,113	4,662
Net income	$ 37,260	$ 32,406	30,047
Common Class A [Member]
Other income (expense):
Net income			$ 25,423
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 1.48	$ 1.30	$ 1.08
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 1.45	$ 1.26	$ 1.04
Weighted average shares and share equivalents outstanding
Weighted average shares and share equivalents outstanding, basic (in shares)	25,170	24,809	23,562
Weighted average shares and share equivalents outstanding, diluted (in shares)	25,696	25,653	24,448
Common Class B [Member]
Other income (expense):
Net income			$ 4,624
Basic earnings per share:
Basic earnings per share (in dollars per share)			$ 1.31
Diluted earnings per share:
Diluted earnings per share (in dollars per share)			$ 1.27
Weighted average shares and share equivalents outstanding
Weighted average shares and share equivalents outstanding, basic (in shares)			3,527
Weighted average shares and share equivalents outstanding, diluted (in shares)			3,628