Note 14 - Income Taxes (Tables)
 12 Months Ended
Dec. 31, 2013
Income Tax Disclosure [Abstract]  
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]
      Years Ended December 31,   
 

2013

2012

2011

         

(in thousands)

       

Current:

                       

State

  $ 1,265     $ 453     $ 276  

U.S.

    11,031       4,288       10,924  

Deferred:

                       

State

    227       294       920  

U.S.

    2,941       1,860       5,608  

Provision (benefit) for income taxes

  $ 15,464     $ 6,895     $ 17,728  
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
      Years Ended December 31,    
      2013       2012       2011  
            (in thousands)          

Taxes at statutory rate

  $ 16,097     $ 3,835     $ 18,159  

Other non-deductible expenses

    145       163       189  

Qualified production activities deduction

    (1,334 )     (193 )     (1,305 )

Charges related to U.S. Attorney investigation

    —       2,625       —  

State taxes, net of federal benefit

    969       485       778  

Excess executive compensation

    —       —       128  

Impact of federal tax credits (1)

    (85 )     —       490  

Change in deferred tax asset valuation allowance (2)

    (77 )     (55 )     (1,120 )

Impact of federal tax rate adjustment to 35%

    —       —       491  

Other

    (251 )     35       (82 )

Provision (benefit) for income taxes

  $ 15,464     $ 6,895     $ 17,728  
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]
    2013     2012  
    (in thousands)  

Deferred tax assets:

               
Assets and accruals not yet deductible   $ 4,369     $ 3,639  
Equity based compensation     3,429       3,243  
Equity in loss of unconsolidated affiliates     125       125  
Tax credit carryforward     225       225  
Pension liability     3,716       5,636  
State income tax     492       404  
Valuation allowance     (584 )     (661 )
Total deferred tax assets     11,772       12,611  
                 

Deferred tax liabilities:

               
Property and equipment     (21,844 )     (20,814 )
Intangible assets     (590 )     (187 )
Pension and other retirement benefits     (1,350 )     (1,272 )
Assets currently deductible     (6,277 )     (4,967 )
Total deferred tax liabilities     (30,061 )     (27,240 )
Net deferred tax liability   $ (18,289 )   $ (14,629 )
                 
Deferred income tax asset (liability) current   $ 1,062     $ 1,165  
Deferred income tax asset (liability) non-current     (19,351 )     (15,794 )
Net deferred tax liability   $ (18,289 )   $ (14,629 )
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]
   

2013

   

2012

   

2011

 
   

(in thousands)

 

Balance at January 1,

  $ 1,514     $ 1,513     $ 896  

Additions for tax positions of prior years

    58       37       451  

Reductions for tax positions of prior years

    —       (36  )     —  

Additions based on tax positions related to the current year

    —       —       166  

Balance at December 31,

  $ 1,572     $ 1,514     $ 1,513