Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue	$ 30,276	$ 27,870
Operating expenses:
Direct	12,500	11,539
Selling, general and administrative	6,686	7,357
Depreciation and amortization	1,106	968
Total operating expenses	20,292	19,864
Operating income	9,984	8,006
Other income (expense):
Interest income	14	11
Interest expense	(27)	(85)
Other, net	9	74
Total other income (expense)	(4)
Income before income taxes	9,980	8,006
Provision for income taxes	3,459	2,500
Net income	6,521	5,506
Common Class A [Member]
Other income (expense):
Net income	$ 3,234	$ 2,735
Basic Earnings Per Share:
Basic earnings per share (in dollars per share)	$ 0.15	$ 0.13
Diluted Earnings Per Share:
Diluted earnings per share (in dollars per share)	0.15	0.13
Dividends Per Share of Common Stock:
Dividends per share (in dollars per share)	$ 0.10	$ 0.08
Weighted average shares and share equivalents outstanding:
Weighted average shares and share equivalents outstanding, basic (in shares)	20,737	20,710
Weighted average shares and share equivalents outstanding, diluted (in shares)	21,245	21,012
Common Class B [Member]
Other income (expense):
Net income	$ 3,287	$ 2,771
Basic Earnings Per Share:
Basic earnings per share (in dollars per share)	$ 0.93	$ 0.79
Diluted Earnings Per Share:
Diluted earnings per share (in dollars per share)	0.91	0.77
Dividends Per Share of Common Stock:
Dividends per share (in dollars per share)	$ 0.60	$ 0.48
Weighted average shares and share equivalents outstanding:
Weighted average shares and share equivalents outstanding, basic (in shares)	3,513	3,489
Weighted average shares and share equivalents outstanding, diluted (in shares)	3,576	3,549