Condensed Consolidating Financial Information (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating Activities
Net cash provided by (used in) operating activities			$ 13,813	$ 12,302
Investing Activities
Net transactions with affiliates			0	0
Capital expenditures	$ (2,165)	$ (1,950)	(5,862)	(5,196)
Cash paid for intangible assets			(916)	(735)
Acquisitions and construction of real estate properties			(116)	(28)
Acquisitions, net of cash acquired			(286)	(477)
Proceeds from sales of businesses and investments			420	622
Purchases of investments			(712)	(145)
Other			268	(121)
Net cash provided by (used in) investing activities			(7,204)	(6,080)
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			(220)	(437)
Proceeds from borrowings			3,996	4,182
Repurchases and repayments of debt			(4,353)	(3,172)
Repurchases and retirements of common stock			(5,770)	(2,250)
Dividends paid			(1,823)	(1,676)
Issuances of common stock			35	33
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			(178)	(170)
Other			(313)	97
Net cash provided by (used in) financing activities			(8,626)	(3,393)
Increase (decrease) in cash and cash equivalents			(2,017)	2,829
Cash and cash equivalents, beginning of period			3,910	1,718
Cash and cash equivalents, end of period	1,893	4,547	1,893	4,547
Elimination and Consolidation Adjustments [Member]
Operating Activities
Net cash provided by (used in) operating activities			0	0
Investing Activities
Net transactions with affiliates			0	0
Capital expenditures			0	0
Cash paid for intangible assets			0	0
Acquisitions and construction of real estate properties			0	0
Acquisitions, net of cash acquired			0	0
Proceeds from sales of businesses and investments			0	0
Purchases of investments			0	0
Other			0	0
Net cash provided by (used in) investing activities			0	0
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			0	0
Proceeds from borrowings			0	0
Repurchases and repayments of debt			0	0
Repurchases and retirements of common stock			0	0
Dividends paid			0	0
Issuances of common stock			0	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			0	0
Other			0	0
Net cash provided by (used in) financing activities			0	0
Increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
Comcast Parent [Member]
Operating Activities
Net cash provided by (used in) operating activities			(725)	(433)
Investing Activities
Net transactions with affiliates			6,786	2,349
Capital expenditures			(19)	(3)
Cash paid for intangible assets			(3)	(2)
Acquisitions and construction of real estate properties			0	0
Acquisitions, net of cash acquired			0	0
Proceeds from sales of businesses and investments			0	0
Purchases of investments			(3)	(10)
Other			7	0
Net cash provided by (used in) investing activities			6,768	2,334
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			0	(1,350)
Proceeds from borrowings			3,996	4,180
Repurchases and repayments of debt			(2,650)	(1,000)
Repurchases and retirements of common stock			(5,770)	(2,250)
Dividends paid			(1,823)	(1,676)
Issuances of common stock			35	33
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			0	0
Other			169	162
Net cash provided by (used in) financing activities			(6,043)	(1,901)
Increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
Comcast Holdings [Member]
Operating Activities
Net cash provided by (used in) operating activities			51	11
Investing Activities
Net transactions with affiliates			(51)	(11)
Capital expenditures			0	0
Cash paid for intangible assets			0	0
Acquisitions and construction of real estate properties			0	0
Acquisitions, net of cash acquired			0	0
Proceeds from sales of businesses and investments			0	0
Purchases of investments			0	0
Other			0	0
Net cash provided by (used in) investing activities			(51)	(11)
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			0	0
Proceeds from borrowings			0	0
Repurchases and repayments of debt			0	0
Repurchases and retirements of common stock			0	0
Dividends paid			0	0
Issuances of common stock			0	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			0	0
Other			0	0
Net cash provided by (used in) financing activities			0	0
Increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
CCCL Parent [Member]
Operating Activities
Net cash provided by (used in) operating activities			69	84
Investing Activities
Net transactions with affiliates			(69)	(84)
Capital expenditures			0	0
Cash paid for intangible assets			0	0
Acquisitions and construction of real estate properties			0	0
Acquisitions, net of cash acquired			0	0
Proceeds from sales of businesses and investments			0	0
Purchases of investments			0	0
Other			0	0
Net cash provided by (used in) investing activities			(69)	(84)
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			0	0
Proceeds from borrowings			0	0
Repurchases and repayments of debt			0	0
Repurchases and retirements of common stock			0	0
Dividends paid			0	0
Issuances of common stock			0	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			0	0
Other			0	0
Net cash provided by (used in) financing activities			0	0
Increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
Combined CCHMO Parents [Member]
Operating Activities
Net cash provided by (used in) operating activities			(93)	(88)
Investing Activities
Net transactions with affiliates			766	88
Capital expenditures			0	0
Cash paid for intangible assets			0	0
Acquisitions and construction of real estate properties			0	0
Acquisitions, net of cash acquired			0	0
Proceeds from sales of businesses and investments			0	0
Purchases of investments			0	0
Other			0	0
Net cash provided by (used in) investing activities			766	88
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			0	0
Proceeds from borrowings			0	0
Repurchases and repayments of debt			(673)	0
Repurchases and retirements of common stock			0	0
Dividends paid			0	0
Issuances of common stock			0	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			0	0
Other			0	0
Net cash provided by (used in) financing activities			(673)	0
Increase (decrease) in cash and cash equivalents			0	0
Cash and cash equivalents, beginning of period			0	0
Cash and cash equivalents, end of period	0	0	0	0
NBCUniversal Media Parent [Member]
Operating Activities
Net cash provided by (used in) operating activities			(1,019)	(998)
Investing Activities
Net transactions with affiliates			2,249	1,761
Capital expenditures			0	0
Cash paid for intangible assets			0	0
Acquisitions and construction of real estate properties			0	0
Acquisitions, net of cash acquired			0	0
Proceeds from sales of businesses and investments			1	1
Purchases of investments			(400)	(6)
Other			(5)	4
Net cash provided by (used in) investing activities			1,845	1,760
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			0	0
Proceeds from borrowings			0	0
Repurchases and repayments of debt			(1,002)	(902)
Repurchases and retirements of common stock			0	0
Dividends paid			0	0
Issuances of common stock			0	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			0	0
Other			0	0
Net cash provided by (used in) financing activities			(1,002)	(902)
Increase (decrease) in cash and cash equivalents			(176)	(140)
Cash and cash equivalents, beginning of period			385	336
Cash and cash equivalents, end of period	209	196	209	196
Comcast Non-Guarantor Subsidiaries [Member]
Operating Activities
Net cash provided by (used in) operating activities			15,530	13,726
Investing Activities
Net transactions with affiliates			(9,681)	(4,103)
Capital expenditures			(5,843)	(5,193)
Cash paid for intangible assets			(913)	(733)
Acquisitions and construction of real estate properties			(116)	(28)
Acquisitions, net of cash acquired			(286)	(477)
Proceeds from sales of businesses and investments			419	621
Purchases of investments			(309)	(129)
Other			266	(125)
Net cash provided by (used in) investing activities			(16,463)	(10,167)
Financing Activities
Proceeds from (repayments of) short-term borrowings, net			(220)	913
Proceeds from borrowings			0	2
Repurchases and repayments of debt			(28)	(1,270)
Repurchases and retirements of common stock			0	0
Dividends paid			0	0
Issuances of common stock			0	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock			(178)	(170)
Other			(482)	(65)
Net cash provided by (used in) financing activities			(908)	(590)
Increase (decrease) in cash and cash equivalents			(1,841)	2,969
Cash and cash equivalents, beginning of period			3,525	1,382
Cash and cash equivalents, end of period	$ 1,684	$ 4,351	$ 1,684	$ 4,351

Decrease in noncontrolling interest balance from payment of dividends or other distributions by the non-wholly owned subsidiary or partially owned entity, included in the consolidation of the parent entity, to the noncontrolling interest holders and dividends for redeemable subsidiary preferred stock.

No definition available.