Note 9 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Domestic Tax Authority [Member] | Non-recurring Tax Credit [Member]
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ 6,500,000
Domestic Tax Authority [Member]
Deferred Tax Assets, Valuation Allowance	0	$ 0
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	7,000,000
Operating Loss Carryforwards	28,600,000
Tax Credit Carryforward, Amount	300,000
State and Local Jurisdiction [Member]
Deferred Tax Assets, Valuation Allowance	1,200,000	1,000,000
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	100,000
Operating Loss Carryforwards	122,900,000
Tax Credit Carryforward, Amount	300,000
Reclassification from Net Current Deferred Income Tax Assets to Net Non-current Deferred Income Tax Liabilities [Member] | December 31, 2014 [Member]
Prior Period Reclassification Adjustment	14,700,000
Interest and Penalties Recognized for Uncertain Tax Positions [Member]
Income Tax Expense (Benefit)	(200,000)	(100,000)	$ (300,000)
Deferred Tax Assets, Valuation Allowance	$ 1,219,000	1,001,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Amount	$ 7,151,000	112,000	250,000
Deferred Tax Liabilities, Net	76,981,000	59,004,000
Liability for Uncertain Tax Positions, Current	3,200,000	1,600,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	900,000	700,000
Income Tax Expense (Benefit)	21,822,000	14,774,000	$ 7,503,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 2,700,000	$ 1,100,000