Quarterly report pursuant to Section 13 or 15(d)

Debt, Net (Details 2)

v3.5.0.2
Debt, Net (Details 2) - USD ($)
$ in Thousands
Sep. 30, 2016
Dec. 31, 2015
Carrying Amount    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value $ 1,873,836 $ 2,077,752
Carrying Amount | Unsecured senior notes    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value 1,187,091 1,185,842
Carrying Amount | Other fixed-rate debt    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value 156,404 282,716
Carrying Amount | Variable-rate debt    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value 530,341 609,194
Estimated Fair Value    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value 1,929,913 2,114,636
Estimated Fair Value | Unsecured senior notes    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value 1,233,860 1,211,658
Estimated Fair Value | Other fixed-rate debt    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value 162,974 291,991
Estimated Fair Value | Variable-rate debt    
Carrying amount and estimated fair value of debt    
Long-term Debt, Fair Value $ 533,079 $ 610,987