Quarterly report pursuant to Section 13 or 15(d)

Debt, Net - Fair Value of Debt (Details)

v3.21.2
Debt, Net - Fair Value of Debt (Details) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Carrying Amount    
Carrying amount and estimated fair value of debt    
Long-term debt $ 2,109,640 $ 2,086,918
Carrying Amount | Unsecured senior notes    
Carrying amount and estimated fair value of debt    
Long-term debt 1,281,640 1,289,461
Carrying Amount | Other fixed-rate debt    
Carrying amount and estimated fair value of debt    
Long-term debt 139,037 140,891
Carrying Amount | Variable-rate secured debt    
Carrying amount and estimated fair value of debt    
Long-term debt 688,963 656,566
Estimated Fair Value    
Carrying amount and estimated fair value of debt    
Long-term debt 2,154,338 2,131,282
Estimated Fair Value | Unsecured senior notes    
Carrying amount and estimated fair value of debt    
Long-term debt 1,324,953 1,334,342
Estimated Fair Value | Other fixed-rate debt    
Carrying amount and estimated fair value of debt    
Long-term debt 138,241 142,838
Estimated Fair Value | Variable-rate secured debt    
Carrying amount and estimated fair value of debt    
Long-term debt $ 691,144 $ 654,102