Quarterly report pursuant to Section 13 or 15(d)

Debt (Details)

v3.8.0.1
Debt (Details)
$ in Thousands
3 Months Ended
Aug. 31, 2017
USD ($)
Mar. 21, 2016
loan
Oct. 30, 2014
loan
Mar. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
Debt disclosures          
Long-term Debt       $ 497,764 $ 497,370
Margin Loan Agreements | Charter          
Debt disclosures          
Number of common shares pledged as collateral | shares       6,800,000  
Value of pledged collateral       $ 2,100,000  
2017 Margin Loan Agreement          
Debt disclosures          
Debt Instrument, Interest Rate, Effective Percentage       3.80%  
SPV | 2017 Margin Loan Agreement          
Debt disclosures          
Long-term Debt, Gross       $ 500,000  
Maximum borrowing capacity $ 1,000,000        
Additional allowed borrowing capacity $ 1,000,000        
Remaining borrowing capacity       $ 500,000  
Basis spread on variable rate 0.50%        
SPV | 2017 Margin Loan Agreement | LIBOR          
Debt disclosures          
Interest rate basis LIBOR        
Basis spread on variable rate 1.00%        
SPV | 2017 Margin Loan Agreement | Three-month LIBOR          
Debt disclosures          
Interest rate basis three-month LIBOR        
Basis spread on variable rate 1.50%        
SPV | 2017 Margin Loan Agreement | Federal Funds Rate          
Debt disclosures          
Basis spread on variable rate 0.50%        
BroadbandSPV          
Debt disclosures          
Number of debt agreements | loan     2    
Cheetah 5          
Debt disclosures          
Number of debt agreements | loan   2