Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue	$ 31,414	$ 28,017	$ 62,894	$ 59,034
Operating expenses:
Direct	11,506	10,996	23,160	23,904
Selling, general and administrative	8,319	7,940	16,026	15,808
Depreciation and amortization	1,440	1,325	2,855	2,608
Total operating expenses	21,265	20,261	42,041	42,320
Operating income	10,149	7,756	20,853	16,714
Other income (expense):
Interest income	8	9	14	54
Interest expense	(533)	(439)	(1,103)	(447)
Other, net	(139)	493	(419)	464
Total other income (expense)	(664)	63	(1,508)	71
Income before income taxes	9,485	7,819	19,345	16,785
Provision (benefit) for income taxes	2,092	(129)	3,756	1,531
Net income	$ 7,393	7,948	$ 15,589	15,254
Denominator for net income per share - basic:
Basic earnings per share (in dollars per share)	$ 0.30		$ 0.63
Numerator for net income per share - diluted:
Diluted earnings per share (in dollars per share)	$ 0.29		$ 0.61
Weighted average shares and share equivalents outstanding:
Weighted average shares and share equivalents outstanding, basic (in shares)	24,789		24,777
Weighted average shares and share equivalents outstanding, diluted (in shares)	25,586		25,549
Common Class A [Member]
Other income (expense):
Net income		$ 7,000		$ 10,630
Denominator for net income per share - basic:
Basic earnings per share (in dollars per share)		$ 0.29		$ 0.47
Numerator for net income per share - diluted:
Diluted earnings per share (in dollars per share)		$ 0.28		$ 0.45
Weighted average shares and share equivalents outstanding:
Weighted average shares and share equivalents outstanding, basic (in shares)		23,957		22,429
Weighted average shares and share equivalents outstanding, diluted (in shares)		24,846		23,350
Common Class B [Member]
Other income (expense):
Net income		$ 948		$ 4,624
Denominator for net income per share - basic:
Basic earnings per share (in dollars per share)		$ 0.27		$ 1.31
Numerator for net income per share - diluted:
Diluted earnings per share (in dollars per share)		$ 0.26		$ 1.27
Weighted average shares and share equivalents outstanding:
Weighted average shares and share equivalents outstanding, basic (in shares)		3,527		3,527
Weighted average shares and share equivalents outstanding, diluted (in shares)		3,620		3,628