Note 5 - Stockholders' Equity (Details Textual) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Mar. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($)	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
Proceeds from Issuance of Common Stock | $			$ 0	$ 167,313
Treasury Stock, Value, Acquired, Cost Method | $			$ 2,000
Common Stock, Capital Shares Reserved for Future Issuance		5,449,148	5,449,148	5,689,219
Dividends, Common Stock | $			$ 0	$ 0	0
Payments of Dividends | $			$ 0	$ 0	$ 0
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	279,200
The 2016 Repurchase Authorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased						75,000,000
Treasury Stock, Shares, Acquired		192,183
Treasury Stock Acquired, Average Cost Per Share | $ / shares			$ 10.38
Treasury Stock, Value, Acquired, Cost Method | $		$ 2,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount | $		$ 73,000	$ 73,000
November 2004 Authorization [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased								2,000,000
Underwritten Offering [Member]
Stock Issued During Period, Shares, New Issues	13,500,000
Share Price | $ / shares	$ 13
Proceeds from Issuance of Common Stock | $	$ 167,300
Issuance of Stock, Underwriting Discount | $	7,500
Issuance of Stock, Underwriting Expenses | $	$ 900
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		257,581	257,581	476,193
Blank Check Preferred Stock [Member]
Preferred Stock, Shares Authorized		20,000,000	20,000,000