Note 14 - Income Taxes (Details) - Summary of Effective Income Tax Rate Reconciliation (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of Effective Income Tax Rate Reconciliation [Abstract]
Tax expense computed at federal statutory rate	$ 35,166	$ 45,439	$ 21,390
State income tax expense, net of federal benefit	3,340	4,544	2,139
Permanent differences	(1,435)	(358)	1,771
Expiration of state net operating loss	3,030	3,874	2,634
Tax expense (benefit) related to an increase (decrease) in unrecognized tax benefits	559	(552)	(1,857)
Write-off of deferred tax asset for deferred compensation retirement plans		11,856
Charitable contributions statute expiration	181
Federal energy credits	(1,131)	(6,530)
Rate changes	866
Change in valuation allowance	(1,665)	(242,833)	(27,661)
Other	(1,579)
Provision for (benefit from) income taxes	$ 37,332	$ (184,560)	$ (1,584)
Effective tax (benefit) rate	37.20%	(142.20%)	(2.60%)