Basis of Presentation and Summary of Significant Accounting Policies (Details) |
12 Months Ended |
|---|---|
|
Dec. 31, 2019
business
segment
| |
| Business And Basis Of Presentation [Line Items] | |
| Number of primary businesses | business | 3 |
| NBCUniversal Media LLC [Member] | |
| Business And Basis Of Presentation [Line Items] | |
| Number of reportable segments | 4 |
| Cable Communications [Member] | |
| Business And Basis Of Presentation [Line Items] | |
| Number of reportable segments | 1 |
| NBCUniversal Segments [Member] | |
| Business And Basis Of Presentation [Line Items] | |
| Number of reportable segments | 4 |
| Sky Limited [Member] | |
| Business And Basis Of Presentation [Line Items] | |
| Number of reportable segments | 1 |