Document and Entity Information	6 Months Ended
	Jun. 30, 2017 shares
Document And Entity Information [Line Items]
Entity Registrant Name	NBCUniversal Media, LLC
Entity Central Index Key	0000902739
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Comcast Corp
Document And Entity Information [Line Items]
Entity Registrant Name	COMCAST CORP
Entity Central Index Key	0001166691
Trading Symbol	cmcsa
Entity Filer Category	Large Accelerated Filer
Class A Common Stock [Member] | Comcast Corp
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding	4,703,928,010
Class B Common Stock [Member] | Comcast Corp
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding	9,444,375