Condensed Consolidated Statement of Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue	$ 21,165	$ 19,269	$ 41,628	$ 38,059
Costs and Expenses:
Programming and production	6,341	5,492	12,415	10,923
Other operating and administrative	6,060	5,763	11,887	11,289
Advertising, marketing and promotion	1,665	1,559	3,195	3,025
Depreciation	1,970	1,868	3,885	3,653
Amortization	571	521	1,158	1,014
Total costs and expenses	16,607	15,203	32,540	29,904
Operating income	4,558	4,066	9,088	8,155
Other Income (Expense):
Interest expense	(758)	(732)	(1,513)	(1,435)
Investment income (loss), net	64	58	123	88
Equity in net income (losses) of investees, net	15	(19)	51	(30)
Other income (expense), net	20	(15)	55	115
Total other income (expense)	(659)	(708)	(1,284)	(1,262)
Income before income taxes	3,899	3,358	7,804	6,893
Income tax expense	(1,364)	(1,278)	(2,622)	(2,589)
Net income	2,535	2,080	5,182	4,304
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	(22)	(52)	(103)	(142)
Net income attributable to Comcast Corporation	$ 2,513	$ 2,028	$ 5,079	$ 4,162
Basic earnings per common share attributable to Comcast Corporation shareholders (in dollars per share)	$ 0.53	$ 0.42	$ 1.07	$ 0.86
Diluted earnings per common share attributable to Comcast Corporation shareholders (in dollars per share)	0.52	0.41	1.05	0.85
Dividends declared per common share (in dollars per share)	$ 0.1575	$ 0.1375	$ 0.315	$ 0.275
NBCUniversal Media LLC [Member]
Revenue	$ 8,331	$ 7,103	$ 16,199	$ 13,964
Costs and Expenses:
Programming and production	3,587	3,037	6,900	6,002
Other operating and administrative	1,895	1,652	3,727	3,247
Advertising, marketing and promotion	778	725	1,484	1,404
Depreciation	265	223	496	415
Amortization	255	242	532	464
Total costs and expenses	6,780	5,879	13,139	11,532
Operating income	1,551	1,224	3,060	2,432
Other Income (Expense):
Interest expense	(149)	(146)	(292)	(293)
Investment income (loss), net	10	8	24	14
Equity in net income (losses) of investees, net	(29)	(19)	(55)	(21)
Other income (expense), net	4	(18)	15	97
Total other income (expense)	(164)	(175)	(308)	(203)
Income before income taxes	1,387	1,049	2,752	2,229
Income tax expense	(99)	(74)	(191)	(172)
Net income	1,288	975	2,561	2,057
Net (income) loss attributable to noncontrolling interests	(12)	(42)	(85)	(122)
Net income attributable to Comcast Corporation	$ 1,276	$ 933	$ 2,476	$ 1,935