Note 5 - Stockholders' Equity (Details Textual) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Dec. 31, 2016 shares	Nov. 06, 2016 shares	Mar. 31, 2006 shares	Nov. 30, 2004 shares	Mar. 31, 2004 shares
Capital Units, Authorized	135,000,000		135,000,000
Common Stock, Shares Authorized	100,000,000		100,000,000		100,000,000
Common Stock, Voting Rights, Votes Per Share	1		1
Dividends, Common Stock | $	$ 0	$ 0	$ 0	$ 0
Treasury Stock, Value, Acquired, Cost Method | $			$ 4,000
Common Stock, Capital Shares Reserved for Future Issuance	7,632,465		7,632,465
March 2004 Authorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased									2,000,000
The 2004-2006 Repurchase Authorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased							5,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased					279,200
The 2016 Repurchase Authorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased						75,000,000
Treasury Stock, Shares, Acquired			322,038
Treasury Stock Acquired, Average Cost Per Share | $ / shares			$ 12.39
Treasury Stock, Value, Acquired, Cost Method | $			$ 4,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount | $	$ 69,000		$ 69,000
November 2004 Authorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased								2,000,000
Common Class A [Member]
Common Stock, Shares Authorized	15,000,000		15,000,000		15,000,000
Common Stock, Voting Rights, Votes Per Share	10		10
Common Stock, Capital Shares Reserved for Future Issuance	1,923,144		1,923,144
Blank Check Preferred Stock [Member]
Preferred Stock, Shares Authorized	20,000,000		20,000,000