Note 10 - Previously Reported Quarterly Results (Details) - USD ($) $ / shares in Units, shares in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Scenario, Previously Reported [Member] | Common Class A [Member]
Income statement:
Basic earnings per share (in dollars per share)		$ 0.12
Diluted earnings per share (in dollars per share)		$ 0.12
Diluted weighted average shares outstanding (in shares)		20,948
Scenario, Previously Reported [Member] | Common Class B [Member]
Income statement:
Basic earnings per share (in dollars per share)		$ 0.74
Diluted earnings per share (in dollars per share)		$ 0.73
Diluted weighted average shares outstanding (in shares)		3,531
Scenario, Previously Reported [Member]
Income statement:
Provision for income taxes		$ 2,833,000
Net income		5,173,000
Statement of cash flows:
Net cash provided by operating activities		4,034,000
Net cash used in investing activities		(1,084,000)
Net cash used in financing activities		(20,326,000)
Effect of exchange rate changes on cash		597,000
Decrease in cash and cash equivalents		(16,779,000)
Cash and cash equivalents at beginning of period	$ 25,366,000	42,145,000		$ 42,145,000
Cash and cash equivalents at end of period		$ 25,366,000
Common Class A [Member]
Income statement:
Net income	$ 2,260,000		$ 2,028,000	$ 4,994,000	$ 3,765,000
Basic earnings per share (in dollars per share)	$ 0.11	$ 0.13	$ 0.10	$ 0.24	$ 0.18
Diluted earnings per share (in dollars per share)	$ 0.11	$ 0.13	$ 0.10	$ 0.24	$ 0.18
Diluted weighted average shares outstanding (in shares)	20,992	21,012	21,029	21,002	21,031
Common Class B [Member]
Income statement:
Net income	$ 2,298,000		$ 2,036,000	$ 5,071,000	$ 3,780,000
Basic earnings per share (in dollars per share)	$ 0.65	$ 0.79	$ 0.58	$ 1.44	$ 1.08
Diluted earnings per share (in dollars per share)	$ 0.64	$ 0.77	$ 0.57	$ 1.41	$ 1.07
Diluted weighted average shares outstanding (in shares)	3,565	3,549	3,522	3,557	3,523
Provision for income taxes	$ 2,478,000	$ 2,500,000	$ 2,261,000	$ 4,978,000	$ 4,563,000
Net income	4,558,000	5,506,000	4,064,000	10,065,000	7,544,000
Statement of cash flows:
Net cash provided by operating activities		4,367,000		11,225,000	9,233,000
Net cash used in investing activities		(1,084,000)		(2,217,000)	(1,632,000)
Net cash used in financing activities		(20,659,000)		(24,647,000)	(6,546,000)
Effect of exchange rate changes on cash		597,000		686,000	(542,000)
Decrease in cash and cash equivalents		(16,779,000)		(14,953,000)	513,000
Cash and cash equivalents at beginning of period	25,366,000	42,145,000		42,145,000	40,042,000
Cash and cash equivalents at end of period	$ 27,192,000	$ 25,366,000	$ 40,555,000	$ 27,192,000	$ 40,555,000