XML 161 R143.htm IDEA: XBRL DOCUMENT v3.8.0.1
LONG-TERM DEBT - Summary of Long-term Debt (Details) - USD ($)
Dec. 31, 2017
Dec. 31, 2016
Apr. 15, 2016
Apr. 06, 2015
Aug. 15, 2014
May 21, 2014
Debt Instrument [Line Items]            
Par Value $ 175,000,000 $ 177,684,000        
Discount (2,059,000) (2,306,000)        
Senior Notes | 5.25% Senior Notes Due April 15, 2025            
Debt Instrument [Line Items]            
Stated interest rate       5.25%    
Par Value 175,000,000 175,000,000   $ 175,000,000    
Discount (2,059,000) (2,281,000)        
Junior Subordinated Debt | 7.50% Amortizing Note Due May 15, 2017            
Debt Instrument [Line Items]            
Stated interest rate     7.50%   7.50% 7.50%
Par Value 0 2,684,000        
Discount $ 0 $ (25,000)