Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Computation of diluted EPS

Computation of Diluted EPS
	2017					2016					2015
Year ended December 31 (in millions, except per share data)	Net Income Attributable to Comcast Corporation		Shares	Per Share Amount		Net Income Attributable to Comcast Corporation		Shares	Per Share Amount		Net Income Attributable to Comcast Corporation		Shares	Per Share Amount
Basic EPS attributable to    Comcast Corporation    shareholders	$	22,714	4,708	$	4.82	$	8,695	4,819	$	1.80	$	8,163	4,972	$	1.64
Effect of dilutive securities:
Assumed exercise or issuance    of shares relating to stock    plans			78					56					63
Diluted EPS attributable to    Comcast Corporation    shareholders	$	22,714	4,786	$	4.75	$	8,695	4,875	$	1.78	$	8,163	5,035	$	1.62