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Significant Transactions (Universal Studios Japan) (Details) - USD ($) $ in Millions |  | 12 Months Ended
--- | --- | ---
Apr. 06, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Business Acquisition [Line Items] |  |  |  |
Payments to acquire additional interest in noncontrolling interest |  | $ 0 | $ 0 | $ 2,299
NBCUniversal Media LLC [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Payments to acquire additional interest in noncontrolling interest |  | $ 0 | $ 0 | $ 2,299
Universal Studios Japan [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Payments to acquire additional interest in noncontrolling interest | $ 2,300 |  |  |
Universal Studios Japan [Member] | NBCUniversal Media LLC [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Payments to acquire additional interest in noncontrolling interest | $ 2,300 |  |  |

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