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v3.19.3.a.u2

Long-Term Debt (Narrative) (Details) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2019 USD ($) | Feb. 28, 2019 GBP (£) | Dec. 31, 2018 USD ($)
Debt Instrument [Line Items] |  |  |
Total fair value of debt | $ 115,800,000,000 |  | $ 114,100,000,000
Cumulative translation gains (losses) related to net investment hedges recorded in AOCI | 637,000,000 |  | (751,000,000)
Maximum borrowing capacity of revolving credit facilities | 9,200,000,000 |  |
Potential increase of maximum borrowing capacity of revolving credit facilities | 12,000,000,000 |  |
Amounts available under revolving credit facilities | 9,200,000,000 |  |
Unused irrevocable standby letters of credit and bank guarantees | 484,000,000 |  |
NBCUniversal Media LLC [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Total fair value of debt | 11,000,000,000.0 |  | 13,200,000,000
Cumulative translation gains (losses) related to net investment hedges recorded in AOCI | $ 120,000,000 |  | 102,000,000
Ownership in cable holding company subsidiaries | 100.00% |  |
NBCUniversal Enterprise [Member] | NBCUniversal Media LLC [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Related party aggregate principal amount senior notes not subject to guarantee | $ 1,500,000,000 |  |
Related party liquidation preference preferred stock not subject to guarantee | $ 725,000,000 |  |
London Interbank Offered Rate (LIBOR) [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Borrowing margin for LIBOR based borrowings | 1.00% |  |
Comcast, Comcast Cable And NBCUniversal Debt Securities [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Principal amount of debt securities subject to guarantee | $ 88,300,000,000 |  |
Comcast And Comcast Cable Debt Securities [Member] | NBCUniversal Media LLC [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Principal amount of debt securities subject to guarantee | 82,500,000,000 |  |
NBCUniversal Enterprise Debt Securities [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Principal amount of debt securities subject to guarantee | 1,500,000,000 |  |
Universal Studios Japan Term Loans [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Principal amount of debt securities subject to guarantee | 2,500,000,000 |  |
Sky Debt Securities [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Principal amount of debt securities subject to guarantee | 9,200,000,000 |  |
Principal amount of debt securities subject to guarantee maturing within the next 5 years | 6,000,000,000.0 |  |
Comcast Revolving Credit Facility due 2022 [Member] | NBCUniversal Media LLC [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Guarantee obligations, maximum capacity of credit facility | 7,600,000,000 |  |
Sky Revolving Credit Facility [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Net repayments of credit facility | 615,000,000 |  |
Credit facility terminated | £ |  | £ 1,000,000,000 |
Cash Flow Hedging [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Amount of foreign currency denominated debt hedged | 3,700,000,000 |  | 3,700,000,000
Cash Flow Hedging [Member] | Currency Swap [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Aggregate asset (liability) fair value | 373,000,000 |  | 399,000,000
Net Investment Hedging [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Amount of net investment in foreign subsidiaries hedged | 14,000,000,000.0 |  | 15,600,000,000
Net Investment Hedging [Member] | Currency Swaps And Foreign Currency Denominated Debt [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Cumulative translation gains (losses) related to net investment hedges recorded in AOCI | 339,000,000 |  | (4,000,000)
Net Investment Hedging [Member] | Currency Swap [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Aggregate asset (liability) fair value | $ (373,000,000) |  | $ (587,000,000)

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