Condensed Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Preferred stock, authorized	20,000,000	20,000,000
Preferred stock, issued	0	0
Accumulated depreciation	$ 47,460	$ 45,410
Accumulated amortization	11,251	10,170
NBCUniversal Media, LLC [Member]
Accumulated depreciation	2,618	2,167
Accumulated amortization	$ 5,444	$ 4,829
Class A Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	7,500,000,000	7,500,000,000
Common stock, issued	2,465,919,210	2,496,598,612
Common stock, outstanding	2,100,458,460	2,131,137,862
Treasury stock common shares	365,460,750	365,460,750
Class A Special Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	7,500,000,000	7,500,000,000
Common stock, issued	418,261,452	471,419,601
Common stock, outstanding	347,326,688	400,484,837
Treasury stock common shares	70,934,764	70,934,764
Class B Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	75,000,000	75,000,000
Common stock, issued	9,444,375	9,444,375
Common stock, outstanding	9,444,375	9,444,375