XML 112 R97.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments (Schedule of Long-Term Debt) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]    
Long-term debt $ 515,919 $ 484,584
Less: current portion (1,799) (51,666)
Long-term debt, net of current portion 514,120 432,918
Revolving Credit Agreement [Member]    
Debt Instrument [Line Items]    
Long-term debt $ 501,000 $ 418,000
Interest rate at end of period 3.40% 2.58%
Maturity date range, end Dec. 31, 2022  
Private Placement, Notes [Member]    
Debt Instrument [Line Items]    
Long-term debt $ 50,000
Interest rate 6.84% 6.84%
Capital Lease Obligations [Member]    
Debt Instrument [Line Items]    
Long-term debt $ 14,919 $ 16,584
Interest rate   5.00%
Maturity date range, end Dec. 31, 2022