Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Schedule of Assets and Liabilities Measured at Fair Value (Details)

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Summary of Significant Accounting Policies - Schedule of Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Liabilities:      
Debt $ 6,585,588   $ 6,987,473
Investment in convertible preferred stock 7,720 $ 612,205  
Level 1      
Liabilities:      
Debt 0   0
Level 2      
Liabilities:      
Debt 6,585,588   6,987,473
Level 3      
Liabilities:      
Debt 0   0
Pandora      
Assets:      
Fair value of investment 554,352   480,472
Pandora | Investee      
Liabilities:      
Investment in convertible preferred stock     480,000
Pandora | Level 1      
Assets:      
Fair value of investment 0   0
Pandora | Level 2      
Assets:      
Fair value of investment 554,352   480,472
Pandora | Level 3      
Assets:      
Fair value of investment $ 0   $ 0