Annual report pursuant to Section 13 and 15(d)

Investments In Affiliates Accounted For Using The Equity Method (Summary of Carrying Amount and Percentage Ownership of Significant Investments in Affiliates) (Details)

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Investments In Affiliates Accounted For Using The Equity Method (Summary of Carrying Amount and Percentage Ownership of Significant Investments in Affiliates) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2015
Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]      
Carrying amount $ 309,000   $ 581,000
LendingTree      
Schedule of Equity Method Investments [Line Items]      
Equity method investment additional shares purchased 450    
QVC Group Common Stock      
Schedule of Equity Method Investments [Line Items]      
Carrying amount $ 40,000   224,000
QVC Group Common Stock | HSNi      
Schedule of Equity Method Investments [Line Items]      
Percentage ownership 100.00%    
Carrying amount     184,000
QVC Group Common Stock | Other      
Schedule of Equity Method Investments [Line Items]      
Carrying amount $ 40,000   40,000
Liberty Ventures common stock      
Schedule of Equity Method Investments [Line Items]      
Carrying amount 269,000   357,000
Equity Method Investment Other Than Temporary Impairment   $ 98,000  
Liberty Ventures common stock | Other      
Schedule of Equity Method Investments [Line Items]      
Carrying amount $ 81,000   110,000
Liberty Ventures common stock | FTD      
Schedule of Equity Method Investments [Line Items]      
Percentage ownership 37.00%    
Market value $ 73,000    
Carrying amount $ 73,000   216,000
Liberty Ventures common stock | LendingTree      
Schedule of Equity Method Investments [Line Items]      
Percentage ownership 27.00%    
Market value $ 1,098,000    
Carrying amount $ 115,000   $ 31,000