Condensed Consolidated Statement of Changes in Equity (Unaudited) - USD ($) $ in Millions	Total	Redeemable Noncontrolling Interests And Redeemable Subsidiary Preferred Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock at Cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	NBCUniversal Media LLC [Member]	NBCUniversal Media LLC [Member] Redeemable Noncontrolling Interest [Member]	NBCUniversal Media LLC [Member] Member's Capital [Member]	NBCUniversal Media LLC [Member] Accumulated Other Comprehensive Income (Loss) [Member]	NBCUniversal Media LLC [Member] Noncontrolling Interest [Member]	Class A Common Stock [Member] Common Stock [Member]	Class B Common Stock [Member] Common Stock [Member]
Beginning balance at Dec. 31, 2015	$ 53,978		$ 38,490	$ 21,413	$ (7,517)	$ (174)	$ 1,709						$ 57	$ 0
Beginning balance at Dec. 31, 2015								$ 34,303		$ 32,834	$ (212)	$ 1,681
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation plans	422		422
Repurchases of common stock under repurchase program and employee plans	(2,640)		(519)	(2,121)
Employee stock purchase plans	78		78
Dividends declared	(1,337)			(1,337)				(853)		(853)
Other comprehensive income (loss)	462					175	287	594			307	287
Contributions from (distributions to) noncontrolling interests, net	(68)						(68)	(75)				(75)
Other	123		(31)				154	160		5		155
Net income (loss)	4,258			4,162			96	2,033		1,935		98
Ending balance at Jun. 30, 2016	55,276		38,440	22,117	(7,517)	1	2,178						57	0
Ending balance at Jun. 30, 2016								36,162		33,921	95	2,146
Beginning balance at Dec. 31, 2015		$ 1,221							$ 372
Increase (Decrease) in Temporary Equity [Roll Forward]
Contributions from (distributions to) noncontrolling interests, net		1							(29)
Other		(20)
Net income (loss)		46							24
Ending balance at Jun. 30, 2016		1,248							367
Beginning balance at Dec. 31, 2016	56,174		38,230	23,076	(7,517)	98	2,231						56	0
Beginning balance at Dec. 31, 2016								41,017		39,036	(135)	2,116
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation plans	288		288
Repurchases of common stock under repurchase program and employee plans	(2,476)		(379)	(2,097)
Employee stock purchase plans	94		94
Dividends declared	(1,498)			(1,498)				(1,141)		(1,141)
Other comprehensive income (loss)	218					136	82	132			50	82
Contributions from (distributions to) noncontrolling interests, net	(49)						(49)	(55)				(55)
Purchase of Universal Studios Japan noncontrolling interests	(2,238)		(696)			194	(1,736)	(2,299)		(704)	141	(1,736)
Contribution from member								662		662
Other	194		(59)				253	556		82		474
Net income (loss)	5,141			5,079			62	2,543		2,476		67
Ending balance at Jun. 30, 2017	55,848		$ 37,478	$ 24,560	$ (7,517)	$ 428	$ 843						$ 56	$ 0
Ending balance at Jun. 30, 2017								41,415		$ 40,411	$ 56	$ 948
Beginning balance at Dec. 31, 2016	1,446	1,446						530	530
Increase (Decrease) in Temporary Equity [Roll Forward]
Contributions from (distributions to) noncontrolling interests, net		(27)							(46)
Other		(9)							10
Net income (loss)		41							18
Ending balance at Jun. 30, 2017	$ 1,451	$ 1,451						$ 512	$ 512