XML 67 R56.htm IDEA: XBRL DOCUMENT v3.5.0.2
Debt - Long-Term Debt (Details) - USD ($)
6 Months Ended 12 Months Ended
Jun. 30, 2016
Dec. 31, 2015
May 23, 2016
May 22, 2016
Aug. 10, 2015
Long-term debt          
Revolving credit facility $ 110,800,000 $ 90,700,000      
Line of Credit | Revolving Credit Facility Due 2020          
Long-term debt          
Revolving credit facility $ 110,800,000 $ 90,700,000      
Weighted-average interest rate 1.90% 1.50%      
Amount available $ 187,035,000 $ 106,985,000      
Total credit facility 300,000,000 200,000,000 $ 300,000 $ 200,000 $ 200,000,000
Standby letters of credit $ 2,165,000 $ 2,315,000      
Commitment fee percentage per annum 0.30% 0.25%