Assets and Liabilities Measured at Fair Value (Schedule of Assets and Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	$ 638,999	$ 570,526
Equity securities	1,749,132	1,800,208
Investment in Liberty Broadband	3,598,079	3,634,786
Indemnification obligation	99,858	0
Exchangeable senior debentures	527,000	0
Exchangeable senior debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Exchangeable senior debentures	527,361	0
Variable forward
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Variable forward	26,980	94,807
Quoted prices in active markets for identical assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	638,999	570,526
Equity securities	1,749,132	1,800,208
Investment in Liberty Broadband	3,598,079	3,634,786
Indemnification obligation	0	0
Quoted prices in active markets for identical assets (Level 1) \| Exchangeable senior debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Exchangeable senior debentures	0	0
Quoted prices in active markets for identical assets (Level 1) \| Variable forward
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Variable forward	0	0
Significant other observable inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Equity securities	0	0
Investment in Liberty Broadband	0	0
Indemnification obligation	99,858	0
Significant other observable inputs (Level 2) \| Exchangeable senior debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Exchangeable senior debentures	527,361	0
Significant other observable inputs (Level 2) \| Variable forward
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Variable forward	$ 26,980	$ 94,807

Indemnification Obligation, Current

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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

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- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109247956&loc=SL51823488-111719

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-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
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-SubTopic 20
-Section 50
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

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- Definition

Fair value portion of investments accounted under the equity method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=66022186&loc=d3e32014-111567

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- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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