Annual report pursuant to Section 13 and 15(d)

Investments in Charter Accounted for Using the Equity Method (Details)

v3.8.0.1
Investments in Charter Accounted for Using the Equity Method (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
May 18, 2016
Dec. 10, 2014
Investments in affiliates accounted for using the Equity Method          
Cash paid to acquire equity method investments   $ 5,000,000      
Charter          
Investments in affiliates accounted for using the Equity Method          
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity $ 2,975,000        
Amortization of Deferred Charges $ 277,000 $ 42,000 $ 52,000    
A/N | Charter          
Investments in affiliates accounted for using the Equity Method          
Proxy agreement term 5 years        
Business Acquisition, Percentage of Voting Interests Acquired 25.01%        
Trading days before proposed sale of A/N 2 days        
first | A/N | Charter          
Investments in affiliates accounted for using the Equity Method          
Maximum percentage of New Charter shares that may be voted by proxy 7.00%        
last | A/N | Charter          
Investments in affiliates accounted for using the Equity Method          
Maximum percentage of New Charter shares that may be voted by proxy 7.00%        
Series C common stock          
Investments in affiliates accounted for using the Equity Method          
Share Price       $ 56.23 $ 40.36
Common stock par value $ 0.01 $ 0.01   $ 0.01  
Series A common stock          
Investments in affiliates accounted for using the Equity Method          
Common stock par value $ 0.01 $ 0.01