Note 5 - Share-Based Compensation (Details) - Stock Option Activity (USD $)	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Common Class A [Member]
Note 5 - Share-Based Compensation (Details) - Stock Option Activity [Line Items]
Number of options	1,174,490		1,444,845
Weighted average exercise price	$ 10.39		$ 10.21
Weighted average remaining contractual terms (years)	6 years 178 days
Aggregate intrinsic value (in thousands)	$ 7,368
Number of options	673,383
Weighted average exercise price	$ 9.23
Weighted average remaining contractual terms (years)	5 years 211 days
Aggregate intrinsic value (in thousands)	4,955
Number of options	24,166	88,344
Weighted average exercise price	$ 18.80
Number of options	(110,625)
Weighted average exercise price	$ 6.60
Aggregate intrinsic value (in thousands)	1,268
Number of options	(183,896)
Weighted average exercise price	$ 12.40
Common Class B [Member]
Note 5 - Share-Based Compensation (Details) - Stock Option Activity [Line Items]
Number of options	188,465		234,802
Weighted average exercise price	$ 21.00		$ 20.76
Weighted average remaining contractual terms (years)	6 years 186 days
Aggregate intrinsic value (in thousands)	4,313
Number of options	106,229
Weighted average exercise price	$ 19.35
Weighted average remaining contractual terms (years)	5 years 222 days
Aggregate intrinsic value (in thousands)	2,606
Number of options	2,217	14,724
Weighted average exercise price	$ 34.15
Number of options	(18,437)
Weighted average exercise price	$ 14.93
Aggregate intrinsic value (in thousands)	$ 400
Number of options	(30,117)
Weighted average exercise price	$ 23.82

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(iii)

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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-Publisher FASB

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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