Quarterly report pursuant to Section 13 or 15(d)

Debt, Net (Details 2)

v3.19.1
Debt, Net (Details 2) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Carrying Amount    
Carrying amount and estimated fair value of debt    
Long-term debt $ 1,876,149 $ 1,823,909
Carrying Amount | Unsecured senior notes    
Carrying amount and estimated fair value of debt    
Long-term debt 1,191,506 1,191,046
Carrying Amount | Other fixed-rate debt    
Carrying amount and estimated fair value of debt    
Long-term debt 147,347 148,308
Carrying Amount | Variable-rate debt    
Carrying amount and estimated fair value of debt    
Long-term debt 537,296 484,555
Estimated Fair Value    
Carrying amount and estimated fair value of debt    
Long-term debt 1,910,137 1,853,206
Estimated Fair Value | Unsecured senior notes    
Carrying amount and estimated fair value of debt    
Long-term debt 1,222,637 1,219,603
Estimated Fair Value | Other fixed-rate debt    
Carrying amount and estimated fair value of debt    
Long-term debt 146,585 147,106
Estimated Fair Value | Variable-rate debt    
Carrying amount and estimated fair value of debt    
Long-term debt $ 540,915 $ 486,497