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	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	[1]	Dec. 31, 2017
Accounts receivable, net	$ 16,544		$ 16,544		$ 14,674		$ 14,806
Other current assets	278		278				35
All other current assets	11,948		11,948
Total current assets	28,770		28,770				52,259
Deferred contract costs	3,371		3,371
All other noncurrent assets	76,576		76,576
Total assets	108,717		108,717				127,316
Deferred revenue	18,642		18,642		$ 16,642		16,878
Other current liabilities	16,795		16,795
Total current liabilities	35,437		35,437				32,310
Deferred income taxes	6,599		6,599				4,030
Other long term liabilities	36,542		36,542
Total liabilities	78,578		78,578				37,275
Retained earnings	(97,027)		(97,027)				77,574
Accumulated other comprehensive income	(2,053)		(2,053)				(1,635)
Other stockholders’ equity	129,219		129,219
Total stockholders’ equity	30,139		30,139				90,041
Total liabilities and stockholders’ equity	108,717		108,717				$ 127,316
Revenue	30,013	$ 28,951	89,047	$ 87,661
Direct expenses	11,780	12,267	35,685	36,706
Selling, general and administrative	7,679	8,430	23,486	22,021
Depreciation and amortization	1,388	1,132	3,996	3,376
Total operating expenses	20,847	21,829	63,167	62,103
Operating income	9,166	7,122	25,880	25,558
Other income (expense)	(783)	51	(711)	66
Income before income taxes	8,383	7,173	25,169	25,624
Provision (benefit) for income taxes	1,391	3,020	2,923	9,198
Net income	6,992	4,153	22,246	16,426
Cumulative translation adjustment	280	599	(418)	1,098
Comprehensive Income	7,272	4,752	21,828	17,524
Deferred income taxes			1,775	184
Reserve for uncertain tax positions			(297)	112
Non-cash share-based compensation expense			1,254	1,273
Loss on disposal of property and equipment			212
Trade accounts receivable and unbilled revenue			(1,841)	(2,298)
Prepaid expenses and other current assets			(1,632)	(1,274)
Deferred contract costs			1
Accounts payable			147	(108)
Accrued expenses, wages, bonus and profit sharing			(1,310)	(293)
Income taxes receivable and payable			(554)	1,157
Deferred revenue			1,939	2,925
Net cash provided by operating activities			25,936	21,480
Net cash used in investing activities			(4,858)	(4,897)
Net cash used in financing activities			(48,193)	(14,682)
Effect of exchange rate changes on cash			(345)	828
Change in cash and cash equivalents			(27,460)	2,729
Cash and cash equivalents at beginning of period			34,733	33,021
Cash and cash equivalents at end of period	7,273	35,750	7,273	35,750
Common Class A [Member]
Net income	$ 6,992	$ 2,062	$ 17,622	$ 8,151
Basic earnings per share (in dollars per share)	$ 0.28	$ 0.10	$ 0.76	$ 0.39
Diluted earnings per share (in dollars per share)	$ 0.27	$ 0.09	$ 0.73	$ 0.38
Common Class B [Member]
Net income		$ 2,091	$ 4,624	$ 8,275
Basic earnings per share (in dollars per share)		$ 0.59	$ 1.31	$ 2.34
Diluted earnings per share (in dollars per share)		$ 0.57	$ 1.27	$ 2.28
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Adjustments for New Accounting Pronouncement [Member]
Accounts receivable, net	$ 1		$ 1
Other current assets	(68)		(68)
All other current assets
Total current assets	(67)		(67)
Deferred contract costs	(3,371)		(3,371)
All other noncurrent assets
Total assets	(3,438)		(3,438)
Deferred revenue	330		330
Other current liabilities
Total current liabilities	330		330
Deferred income taxes	(865)		(865)
Other long term liabilities
Total liabilities	(535)		(535)
Retained earnings	(2,905)		(2,905)
Accumulated other comprehensive income	2		2
Other stockholders’ equity
Total stockholders’ equity	(2,903)		(2,903)
Total liabilities and stockholders’ equity	(3,438)		(3,438)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue	(269)		(221)
Direct expenses	(14)		(73)
Selling, general and administrative	16		73
Depreciation and amortization
Total operating expenses	2
Operating income	(271)		(221)
Other income (expense)
Income before income taxes	(271)		(221)
Provision (benefit) for income taxes	(63)		(51)
Net income	(208)		(170)
Cumulative translation adjustment			2
Comprehensive Income	(208)		(168)
Deferred income taxes			(51)
Reserve for uncertain tax positions
Non-cash share-based compensation expense
Loss on disposal of property and equipment
Trade accounts receivable and unbilled revenue			132
Prepaid expenses and other current assets			(6)
Deferred contract costs
Accounts payable
Accrued expenses, wages, bonus and profit sharing
Income taxes receivable and payable
Deferred revenue			93
Net cash provided by operating activities			(2)
Net cash used in investing activities
Net cash used in financing activities
Effect of exchange rate changes on cash			2
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)		$ (0.01)
Diluted earnings per share (in dollars per share)	(0.01)		(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	$ 16,545		$ 16,545
Other current assets	210		210
All other current assets	11,948		11,948
Total current assets	28,703		28,703
Deferred contract costs
All other noncurrent assets	76,576		76,576
Total assets	105,279		105,279
Deferred revenue	18,972		18,972
Other current liabilities	16,795		16,795
Total current liabilities	35,767		35,767
Deferred income taxes	5,734		5,734
Other long term liabilities	36,542		36,542
Total liabilities	78,043		78,043
Retained earnings	(99,932)		(99,932)
Accumulated other comprehensive income	(2,051)		(2,051)
Other stockholders’ equity	129,219		129,219
Total stockholders’ equity	27,236		27,236
Total liabilities and stockholders’ equity	105,279		105,279
Revenue	29,744		88,826
Direct expenses	11,766		35,612
Selling, general and administrative	7,695		23,559
Depreciation and amortization	1,388		3,996
Total operating expenses	20,849		63,167
Operating income	8,895		25,659
Other income (expense)	(783)		(711)
Income before income taxes	8,112		24,948
Provision (benefit) for income taxes	1,328		2,872
Net income	6,784		22,076
Cumulative translation adjustment	280		(416)
Comprehensive Income	7,064		21,660
Deferred income taxes			1,724
Reserve for uncertain tax positions			(297)
Non-cash share-based compensation expense			1,254
Loss on disposal of property and equipment			212
Trade accounts receivable and unbilled revenue			(1,709)
Prepaid expenses and other current assets			(1,638)
Deferred contract costs			1
Accounts payable			147
Accrued expenses, wages, bonus and profit sharing			(1,310)
Income taxes receivable and payable			(554)
Deferred revenue			2,032
Net cash provided by operating activities			25,934
Net cash used in investing activities			(4,858)
Net cash used in financing activities			(48,193)
Effect of exchange rate changes on cash			(343)
Change in cash and cash equivalents			(27,460)
Cash and cash equivalents at beginning of period			34,733
Cash and cash equivalents at end of period	$ 7,273		$ 7,273
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Common Class A [Member]
Basic earnings per share (in dollars per share)	$ 0.27		$ 0.75
Diluted earnings per share (in dollars per share)	0.26		0.72
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.