Programming and Production Costs (Recognized Programming and Production Costs) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Other Industries [Abstract]
Video distribution programming	$ 3,414	$ 3,046	$ 6,930	$ 6,261
Film and television content:
Owned	2,227	1,936	4,191	4,063
Licensed, including sports rights	3,318	1,584	6,492	4,248
Other	297	251	562	547
Total programming and production costs	9,256	6,817	18,175	15,118
Amortization of owned film and television costs	$ 1,800	$ 1,500	$ 3,500	$ 3,300

The amount of expense recognized in the period for costs associated with video programming and content acquisition and production costs. Programming expenses include the fees paid to license the programming distributed to video customers, such as the programming license fees charged by cable networks and fees charged for retransmission of the signals from local broadcast television stations. Production costs include the amortization of owned and acquired programming, sports rights, direct production costs, residual and participation payments, production overhead, costs associated with the distribution of programming to third-party networks and other distribution platforms, and on-air talent costs. It also includes the amortization of capitalized theatrical film production and acquisition costs and distribution expenses.

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Namespace Prefix:	cmcsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration