Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 4,606
Finance lease liabilities		$ 787
NBCUniversal Media LLC [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liabilities	$ 1,670
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets		4,200
Operating lease liabilities		4,800
Accounting Standards Update 2016-02 [Member] | NBCUniversal Media LLC [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets		1,700
Operating lease liabilities		1,800
Finance lease liabilities		332
Sky Limited [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Additional finance lease liability		$ 229