Investments (Investment and Other Income (Loss), Net) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investment and Other Income (Loss), Net [Line Items]
Equity in net income (losses) of investees, net	$ (355)	$ (76)	$ (295)	$ (56)
Realized and unrealized gains (losses) on equity securities, net	174	(38)	582	(50)
Other income (loss), net	71	3	224	198
Investment and other income (loss), net	(110)	(111)	511	92
NBCUniversal Media LLC [Member]
Investment and Other Income (Loss), Net [Line Items]
Equity in net income (losses) of investees, net	(88)	(119)	(299)	(306)
Realized and unrealized gains (losses) on equity securities, net	178	(91)	436	(128)
Other income (loss), net	79	5	312	57
Investment and other income (loss), net	$ 169	$ (205)	$ 449	$ (377)

Nonoperating income (losses), net recorded in the income statement that are not separately stated.

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Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount of income (loss) for proportionate share of equity method investee's income (loss).

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The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business).

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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.

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