Quarterly report pursuant to Section 13 or 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
 3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2017
Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]      
Carrying amount $ 573,000 $ 573,000 $ 581,000
FTD      
Schedule of Equity Method Investments [Line Items]      
Equity Method Investment Other Than Temporary Impairment 50,000    
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 $ 236,000 $ 236,000 224,000
QVC Group Common Stock | HSN, Inc.      
Schedule of Equity Method Investments [Line Items]      
Percentage ownership 38.00% 38.00%  
Carrying amount $ 198,000 $ 198,000 184,000
QVC Group Common Stock | Other      
Schedule of Equity Method Investments [Line Items]      
Carrying amount 38,000 38,000 40,000
Liberty Ventures common stock      
Schedule of Equity Method Investments [Line Items]      
Carrying amount 337,000 337,000 357,000
Liberty Ventures common stock | Other      
Schedule of Equity Method Investments [Line Items]      
Carrying amount $ 91,000 $ 91,000 110,000
Liberty Ventures common stock | FTD      
Schedule of Equity Method Investments [Line Items]      
Percentage ownership 37.00% 37.00%  
Carrying amount $ 133,000 $ 133,000 216,000
Liberty Ventures common stock | LendingTree      
Schedule of Equity Method Investments [Line Items]      
Percentage ownership 27.00% 27.00%  
Carrying amount $ 113,000 $ 113,000 $ 31,000
Level 1 | QVC Group Common Stock | HSN, Inc.      
Schedule of Equity Method Investments [Line Items]      
Market value 782,000 782,000  
Level 1 | Liberty Ventures common stock | FTD      
Schedule of Equity Method Investments [Line Items]      
Market value 133,000 133,000  
Level 1 | Liberty Ventures common stock | LendingTree      
Schedule of Equity Method Investments [Line Items]      
Market value $ 788,000 $ 788,000