Note 8 - Stockholders' Equity (Details) - Statement of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	3 Months Ended											3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Common Stock [Member] Voting Common Stock [Member]	Mar. 31, 2013 Common Stock [Member] Voting Common Stock [Member]	Dec. 31, 2012 Common Stock [Member] Voting Common Stock [Member]	Mar. 31, 2014 Common Stock [Member] Nonvoting Common Stock [Member]	Dec. 31, 2013 Common Stock [Member] Nonvoting Common Stock [Member]	Mar. 31, 2014 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Mar. 31, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Dec. 31, 2012 Accumulated Other Comprehensive Income (Loss) [Member]	Mar. 31, 2014 Retained Earnings [Member]	Mar. 31, 2013 Retained Earnings [Member]	Mar. 31, 2014 Noncontrolling Interest [Member]	Mar. 31, 2013 Noncontrolling Interest [Member]
Note 8 - Stockholders' Equity (Details) - Statement of Stockholders' Equity [Line Items]
Balance	$ 735,237	$ 286,991	$ 557,754	$ 133,000	$ 133,000	$ 12,483	$ 12,483	$ 5,668	$ 5,668	$ (987)	$ (987)	$ 161,076	$ 154,936	$ (1,744)	$ 42
Net income (loss)	5,439	3,019										5,385	3,114	54	(95)
Exercise of stock options	394		394
Stock-based compensation	584		584
Other	(19)		(19)
Balance	$ 741,635	$ 290,010	$ 558,713	$ 133,000	$ 133,000	$ 12,483	$ 12,483	$ 5,668	$ 5,668	$ (987)	$ (987)	$ 166,461	$ 158,050	$ (1,690)	$ (53)