Condensed Consolidated Statements of Income (unaudited) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue	$ 22,354,000	$ 20,632,000	$ 47,260,000	$ 43,039,000
Operating expenses:
Direct	9,498,000	8,633,000	19,744,000	17,564,000
Selling, general and administrative	6,391,000	5,569,000	12,884,000	11,720,000
Depreciation and amortization	931,000	1,214,000	1,882,000	2,457,000
Total operating expenses	16,820,000	15,416,000	34,510,000	31,741,000
Operating income	5,534,000	5,216,000	12,750,000	11,298,000
Other income (expense):
Interest income	12,000	6,000	31,000	12,000
Interest expense	(101,000)	(140,000)	(217,000)	(282,000)
Other, net	18,000	29,000	32,000	14,000
Total other expense	(71,000)	(105,000)	(154,000)	(256,000)
Income before income taxes	5,463,000	5,111,000	12,596,000	11,042,000
Provision for income taxes	2,029,000	1,172,000	4,692,000	3,253,000
Net income	3,434,000	3,939,000	7,904,000	7,789,000
Common Class A [Member]
Other income (expense):
Earnings per share, basic (in Dollars per share)	$ 0.08	$ 0.10	$ 0.19	$ 0.19
Earnings per share, diluted (in Dollars per share)	$ 0.08	$ 0.09	$ 0.19	$ 0.19
Dividends per share of common stock		40	50	90
Weighted average shares and share equivalents outstanding, basic (in Shares)	20,672	20,254	20,671	20,206
Weighted average shares and share equivalents outstanding, diluted (in Shares)	21,085	20,829	21,074	20,792
Common Class B [Member]
Other income (expense):
Earnings per share, basic (in Dollars per share)	$ 0.50	$ 0.58	$ 1.15	$ 1.16
Earnings per share, diluted (in Dollars per share)	$ 0.49	$ 0.57	$ 1.12	$ 1.12
Dividends per share of common stock		$ 260	$ 310	$ 520
Weighted average shares and share equivalents outstanding, basic (in Shares)	3,445	3,376	3,445	3,368
Weighted average shares and share equivalents outstanding, diluted (in Shares)	3,516	3,471	3,513	3,465