v3.8.0.1
Long-Term Debt - Schedule of Outstanding Senior Notes Issuances (Details) - USD ($)
Sep. 30, 2017
Jun. 27, 2017
Dec. 31, 2016
Debt Instrument [Line Items]      
Unamortized debt issuance costs $ 8,070,000   $ 11,091,000
Senior notes, net 254,430,000   351,409,000
Senior Notes [Member]      
Debt Instrument [Line Items]      
Principal 262,500,000   362,500,000
Unamortized debt issuance costs 8,070,000   11,091,000
Senior notes, net 254,430,000   351,409,000
Senior Notes [Member] | 2016 Senior Notes [Member]      
Debt Instrument [Line Items]      
Principal 110,000,000   110,000,000
Unamortized debt issuance costs 3,664,000   3,694,000
Senior notes, net 106,336,000   106,306,000
Original debt issuance costs $ 3,715,000    
Coupon rate 6.625%    
Effective interest rate 7.07%    
Senior Notes [Member] | 2013 Senior Notes [Member]      
Debt Instrument [Line Items]      
Principal $ 152,500,000   152,500,000
Unamortized debt issuance costs 4,406,000   4,532,000
Senior notes, net 148,094,000   147,968,000
Original debt issuance costs $ 5,054,000    
Coupon rate 7.75%    
Effective interest rate 8.04%    
Senior Notes [Member] | 2012 Senior Notes [Member]      
Debt Instrument [Line Items]      
Principal $ 0 $ 100,000,000 100,000,000
Unamortized debt issuance costs 0   2,865,000
Senior notes, net 0   $ 97,135,000
Original debt issuance costs $ 3,406,000    
Coupon rate 8.00%    
Effective interest rate 8.31%