Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Jan. 01, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Operating lease expense inclusive of short-term and variable lease expenses			$ 1,200	$ 1,100	$ 1,100
Weighted average remaining lease term for operating leases			19 years	9 years
Weighted average discount rate used to calculate operating lease liabilities			3.94%	3.58%
Cash payments for operating leases			$ 987	$ 936	$ 914
Carrying value of contractual obligation			1,100
Contractual value of a potential obligation			$ 1,500
Universal Beijing Resort
Commitments And Contingencies [Line Items]
Operating lease assets and liabilities recognized	$ 2,800
NBCUniversal Enterprise
Commitments And Contingencies [Line Items]
Payments for repurchase of redeemable subsidiary preferred stock		$ 725