Note 7 - Share-Based Compensation (Details) - Stock Option Activity (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Common Class A [Member]
Note 7 - Share-Based Compensation (Details) - Stock Option Activity [Line Items]
Number of options	1,444,845	1,367,754
Weighted average exercise price (in Dollars per share)	$ 10.21	$ 8.45
Weighted average remaining contractual terms (years)	6 years 175 days
Aggregate intrinsic value (in thousands) (in Dollars)	$ 12,438
Number of options	693,975
Weighted average exercise price (in Dollars per share)	$ 8.96
Weighted average remaining contractual terms (years)	5 years 135 days
Aggregate intrinsic value (in thousands) (in Dollars)	6,846,000
Number of options	232,344	238,890	498,024
Weighted average exercise price (in Dollars per share)	$ 15.98
Number of options	(155,253)
Weighted average exercise price (in Dollars per share)	$ 3.36
Aggregate intrinsic value (in thousands) (in Dollars)	1,126,000	5,600,000	900,000
Common Class B [Member]
Note 7 - Share-Based Compensation (Details) - Stock Option Activity [Line Items]
Number of options	234,802	227,959
Weighted average exercise price (in Dollars per share)	$ 20.76	$ 18.45
Weighted average remaining contractual terms (years)	6 years 197 days
Aggregate intrinsic value (in thousands) (in Dollars)	3,276
Number of options	109,662
Weighted average exercise price (in Dollars per share)	$ 18.85
Weighted average remaining contractual terms (years)	5 years 156 days
Aggregate intrinsic value (in thousands) (in Dollars)	1,739,000
Number of options	38,718	39,815	83,004
Weighted average exercise price (in Dollars per share)	$ 29.35
Number of options	(31,875)
Weighted average exercise price (in Dollars per share)	$ 14.69
Aggregate intrinsic value (in thousands) (in Dollars)	$ 992,000	$ 941,000	$ 150,000