Supplemental Financial Information (Net Cash Provided by Operating Activities)(Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Supplemental Financial Information [Line Items]
Net income	$ 2,535	$ 2,080	$ 5,182	$ 4,304
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,541	2,389	5,043	4,667
Share-based compensation			391	331
Noncash interest expense (income), net			122	113
Equity in net (income) losses of investees, net	(15)	19	(51)	30
Cash received from investees			49	42
Net (gain) loss on investment activity and other			(110)	(126)
Deferred income taxes			470	618
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Current and noncurrent receivables, net			18	172
Film and television costs, net			277	(171)
Accounts payable and accrued expenses related to trade creditors			(144)	(104)
Other operating assets and liabilities			(433)	(82)
Net cash provided by operating activities			10,814	9,794
NBCUniversal Media LLC [Member]
Supplemental Financial Information [Line Items]
Net income	1,288	975	2,561	2,057
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	520	465	1,028	879
Equity in net (income) losses of investees, net	$ 29	$ 19	55	21
Cash received from investees			44	31
Net (gain) loss on investment activity and other			(26)	(92)
Deferred income taxes			19	64
Changes in operating assets and liabilities, net of effects of acquisitions and divestitures:
Current and noncurrent receivables, net			(95)	145
Film and television costs, net			275	(179)
Accounts payable and accrued expenses related to trade creditors			(220)	(185)
Other operating assets and liabilities			(115)	(263)
Net cash provided by operating activities			$ 3,526	$ 2,478