Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash surrender value of life insurance policies	$ 423	$ 351
Expenses related to retirement investment plans	573	546	$ 458
Severance costs	359	243	203
NBCUniversal Media LLC [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expenses related to retirement investment plans	229	213	201
Severance costs	$ 125	$ 146	$ 108

Carrying amount as of the balance sheet date of amounts which could be received based on the terms of the insurance contract upon surrendering life policies owned by the entity.

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Amount of cost for defined contribution plan.

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Amount of other expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses associated with a discontinued operation or an asset retirement obligation.

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