XML 97 R76.htm IDEA: XBRL DOCUMENT v3.8.0.1
Debt And Credit Agreements (Narrative) (Details)
 12 Months Ended
Dec. 31, 2017
USD ($)
Mar. 01, 2016
USD ($)
Apr. 23, 2012
USD ($)
Line of Credit Facility [Line Items]      
Credit spread over LIBOR, basis points 1.75%    
Available credit under the Credit Agreement $ 248,000,000    
Secured Revolving Credit Facility [Member]      
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity   $ 400,000,000  
Line Of Credit Facility Term 5 years    
Line of credit facility, option to increase additional amount   50,000,000  
Amount borrowed under the Credit Agreement   $ 107,000,000  
Line of credit facility, covenant terms, maximum debt to EBITDA ratio 4.00    
Line of credit facility, covenant terms, minimum adjusted EBIT-to-interest expense ratio 2.50    
Line of credit facility, covenant terms, maximum aggregate distributions $ 100,000,000    
Line of credit facility, covenant terms, percentage of shareholders' equity to net income 50.00%    
Credit Facility covenant leverage ratio three times limitation 3.00    
Credit Facility limitation on dividend payments at leverage ratio greater than 3.00x $ 4,000,000    
Credit Facility, covenants, 50% of net income limitation when leverage ratio exceeds 3.00x 50.00%    
Credit Facility covenant three point five times leverage ratio 350.00%    
Credit Facility fixed charge coverage one pt two ratio limitation 120.00%    
Unsecured Revolving Credit Facility      
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity     $ 350,000,000