Note 1 - Summary of Significant Accounting Policies - Impact of the Adoption of ASC 606 on the Consolidated Financial Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018	[1]	Dec. 31, 2015
Accounts receivable, net	$ 11,922	$ 14,806		$ 14,674
Other current assets	224	35
All other current assets	16,264
Total current assets	28,410	52,259
Deferred contract costs	3,484
All other noncurrent assets	76,138
Total assets	108,032	127,316	$ 120,624
Deferred revenue	16,244	16,878		$ 16,642
Other current liabilities	30,865
Total current liabilities	47,109	32,310
Deferred income taxes	6,276	4,030
Other long term liabilities	35,564
Total liabilities	88,949	37,275
Retained earnings	(106,339)	77,574
Accumulated other comprehensive income	(2,916)	(1,635)
Other stockholders’ equity	128,338
Total stockholders’ equity	19,083	90,041	82,806			$ 74,222
Total liabilities and stockholders’ equity	108,032	127,316
Revenue	119,686	117,559	109,384
Direct expenses	47,577	49,068	45,577
Selling, general and administrative	31,371	29,686	28,385
Depreciation and amortization	5,463	4,586	4,225
Total operating expenses	84,411	83,340	78,187
Operating income	35,275	34,219	31,197
Other income (expense)	(566)	64	159
Income before income taxes	34,709	34,283	31,356
Provision (benefit) for income taxes	4,662	11,340	10,838
Net income	30,047
Cumulative translation adjustment	(1,281)	991	369
Comprehensive Income	28,766	23,934	20,887
Deferred income taxes	1,476	(684)	798
Liability for uncertain tax positions	(288)	181	73
Non-cash share-based compensation expense	1,514	1,845	1,929
Loss on disposal of property and equipment	186	26	22
Trade accounts receivable	2,767	(2,340)	(1,137)
Prepaid expenses and other current assets	(833)	(565)	(535)
Deferred contract costs	(113)
Accounts payable	(39)	12	(15)
Accrued expenses, wages, bonus and profit sharing	(566)	1,759	440
Income taxes receivable and payable	686	(1,023)	105
Deferred revenue	(452)	1,351	643
Net cash provided by operating activities	39,848	28,091	26,843
Net cash used in investing activities	(5,971)	(6,118)	(3,750)
Net cash used in financing activities	(54,497)	(21,116)	(32,502)
Effect of exchange rate changes on cash	(1,122)	855	285
Change in cash and cash equivalents	(21,742)	1,712	(9,124)
Cash and cash equivalents at beginning of period	34,733	33,021	42,145
Cash and cash equivalents at end of period	$ 12,991	$ 34,733	$ 33,021
Common Class A [Member]
Basic earnings per share (in dollars per share)	$ 1.08	$ 0.54	$ 0.49
Diluted earnings per share (in dollars per share)	$ 1.04	$ 0.52	$ 0.48
Common Class B [Member]
Net income	$ 4,624	$ 11,555	$ 10,341
Basic earnings per share (in dollars per share)	$ 1.31	$ 3.26	$ 2.93
Diluted earnings per share (in dollars per share)	$ 1.27	$ 3.18	$ 2.88
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Adjustments for New Accounting Pronouncement [Member]
Accounts receivable, net	$ 5
Other current assets	(53)
All other current assets	94
Total current assets	46
Deferred contract costs	(3,484)
All other noncurrent assets
Total assets	(3,438)
Deferred revenue	327
Other current liabilities
Total current liabilities	327
Deferred income taxes	(871)
Other long term liabilities
Total liabilities	(544)
Retained earnings	(2,888)
Accumulated other comprehensive income	(6)
Other stockholders’ equity
Total stockholders’ equity	(2,894)
Total liabilities and stockholders’ equity	(3,438)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue	(191)
Direct expenses	(82)
Selling, general and administrative	101
Depreciation and amortization
Total operating expenses	19
Operating income	(210)
Other income (expense)
Income before income taxes	(210)
Provision (benefit) for income taxes	(57)
Net income	(153)
Cumulative translation adjustment	(6)
Comprehensive Income	(159)
Deferred income taxes	(57)
Liability for uncertain tax positions
Non-cash share-based compensation expense
Loss on disposal of property and equipment
Trade accounts receivable	122
Prepaid expenses and other current assets	(115)
Deferred contract costs	113
Accounts payable
Accrued expenses, wages, bonus and profit sharing
Income taxes receivable and payable
Deferred revenue	90
Net cash provided by operating activities
Net cash used in investing activities
Net cash used in financing activities
Effect of exchange rate changes on cash
Change in cash and cash equivalents
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member] | Common Class A [Member]
Basic earnings per share (in dollars per share)	$ (0.01)
Diluted earnings per share (in dollars per share)	(0.01)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member] | Common Class B [Member]
Basic earnings per share (in dollars per share)
Diluted earnings per share (in dollars per share)	$ 0.01
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Accounts receivable, net	$ 11,927
Other current assets	171
All other current assets	16,358
Total current assets	28,456
Deferred contract costs
All other noncurrent assets	76,138
Total assets	104,594
Deferred revenue	16,571
Other current liabilities	30,865
Total current liabilities	47,436
Deferred income taxes	5,405
Other long term liabilities	35,564
Total liabilities	88,405
Retained earnings	(109,227)
Accumulated other comprehensive income	(2,922)
Other stockholders’ equity	128,338
Total stockholders’ equity	16,189
Total liabilities and stockholders’ equity	104,594
Revenue	119,495
Direct expenses	47,495
Selling, general and administrative	31,472
Depreciation and amortization	5,463
Total operating expenses	84,430
Operating income	35,065
Other income (expense)	(566)
Income before income taxes	34,499
Provision (benefit) for income taxes	4,605
Net income	29,894
Cumulative translation adjustment	(1,287)
Comprehensive Income	28,607
Deferred income taxes	1,419
Liability for uncertain tax positions	(288)
Non-cash share-based compensation expense	1,514
Loss on disposal of property and equipment	186
Trade accounts receivable	2,889
Prepaid expenses and other current assets	(948)
Deferred contract costs
Accounts payable	(39)
Accrued expenses, wages, bonus and profit sharing	(566)
Income taxes receivable and payable	686
Deferred revenue	(362)
Net cash provided by operating activities	39,848
Net cash used in investing activities	(5,971)
Net cash used in financing activities	(54,497)
Effect of exchange rate changes on cash	(1,122)
Change in cash and cash equivalents	(21,742)
Cash and cash equivalents at beginning of period	34,733
Cash and cash equivalents at end of period	$ 12,991	$ 34,733
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Common Class A [Member]
Basic earnings per share (in dollars per share)	$ 1.07
Diluted earnings per share (in dollars per share)	1.03
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Common Class B [Member]
Basic earnings per share (in dollars per share)	1.31
Diluted earnings per share (in dollars per share)	$ 1.28

[1] Represents the December 31, 2017 balance adjusted for the ASC 606 transition adjustments.