Share-based Compensation (Awards Outstanding and Exercisable) (Details)	Sep. 30, 2018 $ / shares shares
Held by Liberty Global employees: \| Options and SARs \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	16,021,880
Options outstanding, weighted average exercise or base price (in dollars per shares) \| $ / shares	$ 32.23
Options exercisable (in shares)	9,579,098
Options exercisable, weighted average exercise price or base price (in dollars per shares) \| $ / shares	$ 32.04
Held by Liberty Global employees: \| Options and SARs \| Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	37,027,043
Options outstanding, weighted average exercise or base price (in dollars per shares) \| $ / shares	$ 30.32
Options exercisable (in shares)	23,213,374
Options exercisable, weighted average exercise price or base price (in dollars per shares) \| $ / shares	$ 29.80
Held by Liberty Global employees: \| RSUs \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	664,539
Held by Liberty Global employees: \| RSUs \| Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	1,336,706
Held by Liberty Global employees: \| PSUs \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	1,750,794
Held by Liberty Global employees: \| PSUs \| Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	3,506,744
Held by former Liberty Global employees: \| Options and SARs \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	1,220,423
Options outstanding, weighted average exercise or base price (in dollars per shares) \| $ / shares	$ 32.81
Options exercisable (in shares)	997,219
Options exercisable, weighted average exercise price or base price (in dollars per shares) \| $ / shares	$ 32.17
Held by former Liberty Global employees: \| Options and SARs \| Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)	2,861,651
Options outstanding, weighted average exercise or base price (in dollars per shares) \| $ / shares	$ 30.62
Options exercisable (in shares)	2,414,209
Options exercisable, weighted average exercise price or base price (in dollars per shares) \| $ / shares	$ 29.88
Held by former Liberty Global employees: \| RSUs \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	12,481
Held by former Liberty Global employees: \| RSUs \| Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	25,000
Held by former Liberty Global employees: \| PSUs \| Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	177,505
Held by former Liberty Global employees: \| PSUs \| Class C
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options outstanding (in shares)	355,419

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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Number of options outstanding, including both vested and non-vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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