XML 85 R55.htm IDEA: XBRL DOCUMENT v3.8.0.1
Note 6 - Senior Notes, Credit Facility and Capital Leases (Details Textual) - USD ($)
$ in Thousands
12 Months Ended
May 31, 2016
Apr. 12, 2013
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2014
Sep. 30, 2017
Underwriting Discount on Senior Notes   2.00%        
Letters of Credit Outstanding, Amount     $ 2,600     $ 2,600
Capital Lease Obligations     11,801 $ 11,500    
Capital Lease Obligations, Current     5,608 5,653    
Capital Lease Obligations, Noncurrent     6,193 5,838    
Capital Leases, Future Minimum Payments Due     12,514      
Capital Leases, Future Minimum Payments, Interest Included in Payments     713      
Revolving Credit Facility [Member]            
Line of Credit Facility, Maximum Borrowing Capacity $ 100,000          
Debt Instrument, Term 3 years          
Long-term Line of Credit     $ 0      
Letter of Credit [Member]            
Letter of Credit Outstanding, Fronting Fee     0.20%      
Letter of Credit [Member] | Minimum [Member]            
Letter of Credit, Participation Fee, Percent     2.25%      
Letter of Credit [Member] | Maximum [Member]            
Letter of Credit, Participation Fee, Percent     3.25%      
Senior Notes [Member]            
Debt Instrument, Face Amount   $ 500,000        
Payment for Pension Benefits         $ 6,500  
Proceeds from Issuance of Senior Long-term Debt   490,000        
Debt Instrument, Unamortized Discount   $ 10,000 $ 4,300      
Debt Instrument, Interest Rate, Stated Percentage   6.875% 6.875%      
Interest Expense, Debt     $ 35,300 20,100    
Interest Costs Capitalized     $ 900 $ 16,200    
Debt Instrument, Redemption Price, Percentage     101.00%      
Senior Notes [Member] | Costs Related to Private Offering and Tender Offer [Member]            
Interest Expense, Debt     $ 900