Quarterly report pursuant to Section 13 or 15(d)

Long-term Investment (Details)

v3.7.0.1
Long-term Investment (Details)
 1 Months Ended 3 Months Ended 5 Months Ended 6 Months Ended 7 Months Ended
Jun. 09, 2017
USD ($)
$ / shares
shares
Jun. 30, 2017
$ / shares
Jun. 30, 2017
USD ($)
$ / shares
Dec. 31, 2017
USD ($)
director
$ / shares
shares
Jun. 30, 2017
USD ($)
$ / shares
Jun. 30, 2016
USD ($)
Dec. 31, 2020
trading_days
$ / shares
Dec. 31, 2017
USD ($)
$ / shares
shares
Jun. 09, 2022
Jun. 09, 2020
Schedule of Equity Method Investments [Line Items]                    
Investment in convertible preferred stock | $         $ 172,500,000 $ 0        
Preferred stock, par value (in dollars per share) | $ / shares   $ 0.001 $ 0.001   $ 0.001          
Pandora                    
Schedule of Equity Method Investments [Line Items]                    
Investment in convertible preferred stock | $ $ 172,500,000                  
Dividend income from investment | $     $ 604,000   $ 604,000          
Gain (loss) on investment | $     $ 0   $ 0          
Pandora | Forecast                    
Schedule of Equity Method Investments [Line Items]                    
Investment ownership percentage       19.00%       19.00%    
Ownership percentage on an as-converted basis       16.00%       16.00%    
Investment in convertible preferred stock | $       $ 307,500,000       $ 480,000,000    
Number of directors designated | director       3            
Minimum ownership percentage for director designation       50.00%       50.00%    
Director designation period       2 years            
Minimum ownership percentage for designation of two directors       75.00%       75.00%    
Pandora | Series A Preferred Stock                    
Schedule of Equity Method Investments [Line Items]                    
Preferred stock, par value (in dollars per share) | $ / shares $ 0.0001                  
Preferred stock dividend rate, percentage   6.00%                
Pandora | Series A Preferred Stock | Forecast                    
Schedule of Equity Method Investments [Line Items]                    
Price per share (in dollars per share) | $ / shares       $ 10.50       $ 10.50    
Common shares issued upon conversion (in shares) | shares       95.2381       95.2381    
Mandatory redemption period       5 years            
Percentage of liquidation preference       100.00%       100.00% 100.00% 100.00%
Convertible preferred stock, stock trigger price | $ / shares             $ 18.375      
Convertible preferred stock, threshold trading days | trading_days             20      
Convertible preferred stock, threshold consecutive trading days | trading_days             30      
Pandora | Series A Preferred Stock | Forecast | Minimum                    
Schedule of Equity Method Investments [Line Items]                    
Mandatory redemption period       3 years            
Pandora | Series A Preferred Stock                    
Schedule of Equity Method Investments [Line Items]                    
Price per share (in dollars per share) | $ / shares $ 1,000                  
Pandora | Series A Preferred Stock | Forecast                    
Schedule of Equity Method Investments [Line Items]                    
Number of shares issued (in shares) | shares       307,500       480,000    
Pandora | Pandora | Series A Preferred Stock                    
Schedule of Equity Method Investments [Line Items]                    
Number of shares issued (in shares) | shares 172,500