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Long-Term Debt (Debt Repayments) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Repurchases and repayments of debt	$ 4,347	$ 4,967
NBCUniversal Enterprise 1.662% senior notes due 2018 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Repurchases and repayments of debt	$ 1,100
Interest rate	1.662%
Senior 5.70% notes due 2018 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Repurchases and repayments of debt	$ 1,000
Interest rate	5.70%
Senior 5.875% notes due 2018 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Repurchases and repayments of debt	$ 900
Interest rate	5.875%
NBCUniveral Enterprise senior floating rate notes due 2018 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Repurchases and repayments of debt	$ 700
Universal Studios Japan term loans maturing 2022
Debt Instrument [Line Items]
Repurchases and repayments of debt	318
Other [Member]
Debt Instrument [Line Items]
Repurchases and repayments of debt	$ 329

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Amount of cash outflow for the payment of debt classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

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