Comcast (CMCSA) 10-K 12 Feb 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Jun. 30, 2013
Document Type	'10-K	'
Amendment Flag	'false	'
Document Period End Date	31-Dec-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'FY	'
Trading Symbol	'cmcsa	'
Entity Registrant Name	'COMCAST CORP	'
Entity Central Index Key	'0001166691	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Current Reporting Status	'Yes	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
NBCUniversal Media, LLC [Member]	'	'
Amendment Flag	'false	'
Entity Registrant Name	'NBCUniversal Media, LLC	'
Entity Central Index Key	'0000902739	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Public Float	'	$0
Entity Well-known Seasoned Issuer	'Yes	'
Class A Common Stock [Member]	'	'
Entity Common Stock, Shares Outstanding	2,138,075,133	'
Entity Public Float	'	88,984
ClassA Special Common Stock [Member]	'	'
Entity Common Stock, Shares Outstanding	459,030,180	'
Entity Public Float	'	$18,733
Class B Common Stock [Member]	'	'
Entity Common Stock, Shares Outstanding	9,444,375	'

Consolidated_Balance_Sheet

Consolidated Balance Sheet (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$1,718	$10,951
Investments [Current]	3,573	1,464
Receivables, net	6,376	5,521
Programming rights	928	909
Other current assets	1,480	1,146
Total current assets	14,075	19,991
Film and television costs	4,994	5,054
Investments	3,770	6,325
Property and equipment, net	29,840	27,232
Franchise rights	59,364	59,364
Goodwill	27,098	26,985
Other intangible assets, net	17,329	17,840
Other noncurrent assets, net	2,343	2,180
Total assets	158,813	164,971
Current Liabilities:	'	'
Accounts payable and accrued expenses related to trade creditors	5,528	6,206
Accrued participations and residuals	1,239	1,350
Deferred revenue	898	851
Accrued expenses and other current liabilities	7,967	5,931
Current portion of long-term debt	3,280	2,376
Total current liabilities	18,912	16,714
Long-term debt, less current portion	44,567	38,082
Deferred income taxes	31,935	30,110
Other noncurrent liabilities	11,384	13,271
Commitments and contingencies	'	'
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	957	16,998
Equity:	'	'
Preferred stock - authorized, 20,000,000 shares; issued, zero	0	0
Common stock	30	31
Additional paid-in capital	38,890	40,547
Retained earnings	19,235	16,280
Treasury stock, 365,460,750 Class A common shares and 70,934,764 Class A Special common shares	-7,517	-7,517
Accumulated other comprehensive income (loss)	56	15
Total Comcast Corporation shareholders' equity	50,694	49,356
Noncontrolling interests	364	440
Total equity	51,058	49,796
Total liabilities and equity	158,813	164,971
NBCUniversal Media, LLC [Member]	'	'
Current Assets:	'	'
Cash and cash equivalents	967	5,921
Receivables, net	4,911	4,028
Programming rights	903	844
Other current assets	615	607
Total current assets	7,396	11,400
Film and television costs	4,983	5,041
Investments	884	1,266
Property and equipment, net	7,650	5,381
Goodwill	14,882	14,770
Intangible assets	14,857	15,420
Other noncurrent assets, net	1,087	1,184
Total assets	51,739	54,462
Current Liabilities:	'	'
Accounts payable and accrued expenses related to trade creditors	1,583	2,348
Accrued participations and residuals	1,239	1,350
Program obligations	657	561
Deferred revenue	846	681
Accrued expenses and other current liabilities	1,465	1,288
Note payable to Comcast	799	'
Current portion of long-term debt	906	10
Total current liabilities	7,495	6,238
Long-term debt, less current portion	10,259	11,231
Accrued participations residuals and program obligations noncurrent	1,015	862
Other noncurrent liabilities	3,412	3,746
Commitments and contingencies	'	'
Redeemable noncontrolling interests	231	131
Equity:	'	'
Member's capital	29,056	31,900
Accumulated other comprehensive income (loss)	-16	-65
Total NBCUniversal member's equity	29,040	31,835
Noncontrolling interests	287	419
Total NBCUniversal equity	29,327	32,254
Total liabilities and equity	51,739	54,462
Class A Common Stock [Member]	'	'
Equity:	'	'
Common stock	25	25
Class B Common Stock [Member]	'	'
Equity:	'	'
Common stock	0	0
ClassA Special Common Stock [Member]	'	'
Equity:	'	'
Common stock	$5	$6

Consolidated_Balance_Sheet_Par

Consolidated Balance Sheet (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Preferred stock, authorized	20,000,000	20,000,000
Preferred stock, issued	0	0
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	2,503,535,883	2,487,739,385
Common stock, outstanding	2,138,075,133	2,122,278,635
Treasury stock common shares	365,460,750	365,460,750
ClassA 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	529,964,944	578,704,227
Common stock, outstanding	459,030,180	507,769,463
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

Consolidated_Statement_of_Inco

Consolidated Statement of Income (NBCUniversal Media, LLC [Member], USD $)	1 Months Ended	11 Months Ended	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Revenue	$1,206	$19,028	$23,650	$23,812
Costs and Expenses:	'	'	'	'
Programming and production	711	9,708	11,770	12,710
Other operating and administrative	307	4,075	4,949	4,763
Advertising, marketing and promotion	153	1,849	2,199	2,232
Depreciation	19	401	639	562
Amortization	8	712	772	764
Total costs and expenses	1,198	16,745	20,329	21,031
Operating income	8	2,283	3,321	2,781
Other Income (Expense):	'	'	'	'
Interest expense	-37	-389	-515	-480
Investment income (loss), net	4	19	17	27
Equity in net income (losses) of investees, net	25	262	-93	183
Other income (expense), net	-29	-129	-402	917
Nonoperating income (expense)	-37	-237	-993	647
Income before income taxes	-29	2,046	2,328	3,428
Income tax expense	4	-185	-206	-197
Net income	-25	1,861	2,122	3,231
Net (income) loss attributable to noncontrolling interests	2	-178	-154	-176
Net income attributable to Parent	($23)	$1,683	$1,968	$3,055

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive Income (USD $)	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Net income	$7,135	$7,865	$5,157	($25)	$1,861	$2,122	$3,231
Unrealized gains (losses) on marketable securities, net of deferred taxes	185	161	4	'	'	'	'
Deferred gains (losses) on cash flow hedges, net of deferred taxes	25	58	-25	'	'	'	'
Amounts Reclassified To Net Income:	'	'	'	'	'	'	'
Realized (gains) losses on marketable securities, net of deferred taxes	-301	'	-8	'	'	'	'
Realized (gains) losses on cash flow hedges, net of deferred taxes	-3	-15	20	'	'	'	'
Employee benefit obligations, net of deferred taxes	181	-31	-70	4	-64	95	14
Currency translation adjustments, net of deferred taxes	-29	'	-12	1	-14	-41	-1
Other, net	'	'	'	-2	0	-5	0
Comprehensive income	7,193	8,038	5,066	-22	1,783	2,171	3,244
Net (income) loss attributable to noncontrolling interests	'	'	'	2	-178	-154	-176
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	-319	-1,662	-997	'	'	'	'
Other comprehensive (income) loss attributable to noncontrolling interests	9	-6	38	'	'	'	'
Comprehensive income attributable to Parent	$6,883	$6,370	$4,107	($20)	$1,605	$2,017	$3,068

Consolidated_Statement_of_Comp1

Consolidated Statement of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Unrealized gains (losses) on marketable securities, deferred taxes	($110)	($95)	($2)
Deferred gains (losses) on cash flow hedges, deferred taxes	-14	-34	15
Realized (gains) losses on marketable securities, deferred taxes	177	0	5
Realized (gains) losses on cash flow hedges, deferred taxes	2	8	-11
Employee benefit obligations, deferred taxes	-108	22	22
Currency translation adjustments, deferred taxes	$12	$0	$3

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (USD $)	12 Months Ended			11 Months Ended	12 Months Ended		1 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jan. 28, 2011
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
				Successor [Member]	Successor [Member]	Successor [Member]	Predecessor [Member]
Operating Activities	'	'	'	'	'	'	'
Net income	$7,135	$7,865	$5,157	$1,861	$2,122	$3,231	($25)
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'	'	'	'	'
Depreciation and amortization	7,871	7,798	7,636	1,113	1,411	1,326	27
Amortization of film and television costs	8,249	9,454	6,787	6,766	8,185	9,399	549
Share-based compensation	419	371	344	17	7	7	48
Noncash interest expense (income), net	167	193	146	'	'	'	'
Equity in net (income) losses of investees, net	86	-959	35	-262	93	-183	-25
Cash received from investees	120	195	311	301	90	189	0
Net (gain) loss on investment activity and other	-169	-1,062	23	30	345	-1,093	27
Deferred income taxes	16	139	1,058	27	-10	15	-473
Change in current and noncurrent receivables, net	-721	-823	-427	-357	-752	-643	-675
Change in film and television costs	-8,205	-9,432	-7,080	-7,018	-8,183	-9,299	-590
Change in accounts payable and accrued expenses related to trade creditors	-667	366	-20	95	-789	51	399
Change in other operating assets and liabilities	-141	749	375	296	505	333	109
Net cash provided by (used in) operating activities	14,160	14,854	14,345	2,869	3,024	3,333	-629
Investing Activities	'	'	'	'	'	'	'
Capital expenditures	-6,596	-5,714	-5,307	-432	-1,160	-763	-16
Cash paid for intangible assets	-1,009	-923	-954	-249	-113	-113	0
Acquisitions of real estate properties	-1,904	'	'	'	-1,705	'	'
Acquisitions, net of cash acquired	-99	-90	-6,407	-746	-111	-90	0
Proceeds from sales of businesses and investments	1,083	3,102	277	117	2	3,026	331
Return of capital from investees	149	2,362	37	'	131	75	'
Purchases of investments	-1,223	-297	-135	-14	-236	-117	0
Other	85	74	-19	-8	-20	-9	0
Net cash provided by (used in) investing activities	-9,514	-1,486	-12,508	-1,332	-3,212	2,009	315
Financing Activities	'	'	'	'	'	'	'
Proceeds from (repayments of) short-term borrowings, net	1,345	-544	544	550	0	-550	0
Proceeds from borrowings	2,933	4,544	'	0	0	1,995	0
Repurchases and repayments of debt	-2,444	-2,881	-3,216	-1,044	-92	-413	0
Proceeds from borrowings from Comcast	'	'	'	250	799	'	'
Repayments of borrowings from Comcast	'	'	'	-250	0	0	0
Repurchases and retirements of common stock	-2,000	-3,000	-2,141	'	'	'	'
Decrease in short-term loans to GE, net	'	'	'	0	0	0	8,072
Repurchase of preferred stock interest	'	'	'	0	0	0	-332
Distributions to member	'	'	'	-244	-1,422	-964	0
Dividends paid	-1,964	-1,608	-1,187	-315	0	0	-8,041
Redemption Transaction distribution	'	'	'	'	-3,200	'	'
Issuances of common stock	40	233	283	'	'	'	'
Purchase of NBCUniversal noncontrolling common equity interest	-10,761	'	'	'	'	'	'
Distributions to noncontrolling interests	'	'	'	-187	-183	-216	0
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock	-215	-691	-325	'	'	'	'
Settlement of Station Venture liability	-602	'	'	'	-602	'	'
Other	-211	-90	-159	3	-66	-81	1
Net cash provided by (used in) financing activities	-13,879	-4,037	-6,201	-1,237	-4,766	-229	-300
Increase (decrease) in cash and cash equivalents	-9,233	9,331	-4,364	300	-4,954	5,113	-614
Cash and cash equivalents, beginning of year	10,951	1,620	5,984	508	5,921	808	1,084
Cash and cash equivalents, end of year	$1,718	$10,951	$1,620	$808	$967	$5,921	$470

Consolidated_Statement_of_Chan

Consolidated Statement of Changes in Equity (USD $)

Total

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Redeemable Noncontrolling Interests And Redeemable Subisdiary Preferred Stock [Member]

Class A Common Stock [Member]

ClassA Special Common Stock [Member]

Class B Common Stock [Member]

Additional Paid-In Capital [Member]

Additional Paid-In Capital [Member]

Retained Earnings [Member]

Retained Earnings [Member]

Treasury Stock at Cost [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Redeemable Noncontrolling Interest [Member]

Member's Capital [Member]

In Millions

Successor [Member]

Predecessor [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Predecessor [Member]

Predecessor [Member]

Successor [Member]

Predecessor [Member]

Successor [Member]

Predecessor [Member]

Successor [Member]

Successor [Member]

Beginning balance at Dec. 31, 2010

'

'

'

$23,817

'

'

'

'

'

$23,592

'

$320

'

'

'

($13)

'

'

($82)

'

'

Beginning Balance at Dec. 31, 2010

'

'

'

'

'

'

'

0

'

'

'

'

-7,517

'

'

'

'

'

'

'

'

Members Equity Remeasured

'

'

24,351

'

'

'

'

'

'

'

'

'

'

'

'

'

'

262

'

'

24,089

Contribution of Comcast Content business

'

'

4,401

'

'

'

'

'

'

'

'

'

'

'

'

'

'

57

'

136

4,344

Other comprehensive income (loss)

'

'

'

3

'

'

'

'

'

'

'

'

'

'

'

3

'

'

'

'

'

Other

'

'

'

329

'

'

'

'

'

331

'

'

'

'

'

'

'

'

-2

'

'

Net income (loss)

'

'

'

-25

'

'

'

'

'

'

'

-23

'

'

'

'

'

'

-2

'

'

Ending balance at Jan. 28, 2011

'

'

'

15,371

'

'

'

'

'

15,463

'

'

'

'

'

-10

'

'

-82

'

'

Beginning Balance at Dec. 31, 2010

44,434

'

'

'

143

24

8

0

39,780

'

12,158

'

-7,517

-99

'

'

80

'

'

'

'

Stock compensation plans

469

'

'

'

'

1

'

'

509

'

-41

'

'

'

'

'

'

'

'

'

'

Repurchase and retirements of common stock

-2,141

'

'

'

'

'

-1

'

-1,067

'

-1,073

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plans

68

'

'

'

'

'

'

'

68

'

'

'

'

'

'

'

'

'

'

'

'

NBCUniversal transaction

1,869

'

'

'

15,198

'

'

'

1,605

'

'

'

'

'

'

'

264

'

'

'

'

Other comprehensive income (loss)

-53

'

'

'

-38

'

'

'

'

'

'

'

'

-53

'

'

'

'

'

'

'

Dividends declared

-1,233

'

'

'

'

'

'

'

'

'

-1,233

'

'

'

'

'

'

'

'

'

'

Issuance of subsidiary shares to noncontrolling interests

88

'

'

'

83

'

'

'

45

'

'

'

'

'

'

'

43

'

'

'

'

Contributions from (distributions to) noncontrolling interests, net

-161

'

'

'

-214

'

'

'

'

'

'

'

'

'

'

'

-161

'

'

'

'

Net income (loss)

4,315

'

'

'

842

'

'

'

'

'

4,160

'

'

'

'

'

155

'

'

'

'

Ending Balance at Dec. 31, 2011

47,655

'

'

'

16,014

25

7

0

40,940

'

13,971

'

-7,517

-152

'

'

381

'

'

'

'

Beginning balance at Jan. 28, 2011

'

'

28,752

'

'

'

'

'

'

'

'

'

'

'

'

'

'

319

'

136

28,433

Compensation Plans

'

'

17

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

17

Other comprehensive income (loss)

'

'

-78

'

'

'

'

'

'

'

'

'

'

'

-78

'

'

'

'

'

'

Dividends declared

'

'

-244

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-244

Issuance of subsidiary shares to noncontrolling interests

'

'

132

'

'

'

'

'

'

'

'

'

'

'

'

'

'

43

'

40

89

Contributions from (distributions to) noncontrolling interests, net

'

'

-176

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-176

'

-8

'

Other

'

'

-167

'

'

'

'

'

'

'

'

'

'

'

'

'

'

13

'

'

-180

Net income (loss)

'

'

1,845

'

'

'

'

'

'

'

'

'

'

'

'

'

'

162

'

16

1,683

Ending Balance at Dec. 31, 2011

47,655

'

'

'

16,014

25

7

0

40,940

'

13,971

'

-7,517

-152

'

'

381

'

'

'

'

Ending balance at Dec. 31, 2011

'

'

30,081

'

'

'

'

'

'

'

'

'

'

'

-78

'

'

361

'

184

29,798

Stock compensation plans

372

'

'

'

'

'

'

'

612

'

-240

'

'

'

'

'

'

'

'

'

'

Repurchase and retirements of common stock

-3,000

'

'

'

'

'

-1

'

-1,081

'

-1,918

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plans

80

'

'

'

'

'

'

'

80

'

'

'

'

'

'

'

'

'

'

'

'

Compensation Plans

'

'

7

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7

Other comprehensive income (loss)

167

'

13

'

6

'

'

'

'

'

'

'

'

167

13

'

'

'

'

'

'

Dividends declared

-1,736

'

-964

'

'

'

'

'

'

'

-1,736

'

'

'

'

'

'

'

'

'

-964

Purchase of subsidiary shares from noncontrolling interests, net

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-47

'

Contributions from (distributions to) noncontrolling interests, net

-169

'

-184

'

-493

'

'

'

'

'

'

'

'

'

'

'

-169

-184

'

-24

'

Other

76

'

88

'

-43

'

'

'

-4

'

'

'

'

'

'

'

80

84

'

'

4

Net income (loss)

6,351

'

3,213

'

1,514

'

'

'

'

'

6,203

'

'

'

'

'

148

158

'

18

3,055

Ending Balance at Dec. 31, 2012

49,796

'

'

'

16,998

25

6

0

40,547

'

16,280

'

-7,517

15

'

'

440

'

'

'

'

Ending balance at Dec. 31, 2012

'

32,254

32,254

'

'

'

'

'

'

'

'

'

'

'

-65

'

'

419

'

131

31,900

Stock compensation plans

232

'

'

'

'

'

'

'

603

'

-371

'

'

'

'

'

'

'

'

'

'

Repurchase and retirements of common stock

-2,000

'

'

'

'

'

-1

'

-555

'

-1,444

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plans

98

'

'

'

'

'

'

'

98

'

'

'

'

'

'

'

'

'

'

'

'

Compensation Plans

'

'

7

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7

Other comprehensive income (loss)

67

'

49

'

-9

'

'

'

'

'

'

'

'

67

49

'

'

'

'

'

'

Redemption Transaction distribution

'

-3,200

-3,200

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-3,200

Dividends declared

-2,046

'

-1,422

'

'

'

'

'

'

'

-2,046

'

'

'

'

'

'

'

'

'

-1,422

Purchase of NBCUniversal noncontrolling common equity interest

-1,677

'

'

'

-17,006

'

'

'

-1,651

'

'

'

'

-26

'

'

'

'

'

'

'

Purchase of subsidiary shares from noncontrolling interests, net

'

'

-33

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-33

Redeemable subsidiary preferred stock

'

'

'

'

725

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Contributions from (distributions to) noncontrolling interests, net

-136

'

-155

'

-22

'

'

'

'

'

'

'

'

'

'

'

-136

-155

'

-22

'

Other

-210

'

-275

'

70

'

'

'

-152

'

'

'

'

'

'

'

-58

-111

'

102

-164

Net income (loss)

6,934

'

2,102

'

201

'

'

'

'

'

6,816

'

'

'

'

'

118

134

'

20

1,968

Ending Balance at Dec. 31, 2013

51,058

'

'

'

957

25

5

0

38,890

'

19,235

'

-7,517

56

'

'

364

'

'

'

'

Ending balance at Dec. 31, 2013

'

$29,327

$29,327

'

'

'

'

'

'

'

'

'

'

'

($16)

'

'

$287

'

$231

$29,056

Consolidated_Statement_of_Chan1

Consolidated Statement of Changes in Equity (Predecessor) (USD $)

Total

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

Additional Paid-In Capital [Member]

Additional Paid-In Capital [Member]

Retained Earnings [Member]

Retained Earnings [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Accumulated Other Comprehensive Income (Loss) [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

Noncontrolling Interests [Member]

In Millions

Successor [Member]

Predecessor [Member]

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

N B C Universal Media L L C [Member]

Predecessor [Member]

Predecessor [Member]

Successor [Member]

Predecessor [Member]

Successor [Member]

Predecessor [Member]

Beginning balance at Dec. 31, 2010

'

'

'

$23,817

'

$23,592

'

$320

'

'

($13)

'

'

($82)

Compensation plans

'

'

'

48

'

48

'

'

'

'

'

'

'

'

Dividends declared

'

'

'

-8,143

'

-7,846

'

-297

'

'

'

'

'

'

Other

'

'

'

-329

'

-331

'

'

'

'

'

'

'

2

Other comprehensive income (loss)

'

'

'

3

'

'

'

'

'

'

3

'

'

'

Net income (loss)

'

'

'

-25

'

'

'

-23

'

'

'

'

'

-2

Ending balance at Jan. 28, 2011

'

'

28,752

15,371

'

15,463

'

'

'

'

-10

'

319

-82

Other

'

'

167

'

'

'

'

'

'

'

'

'

-13

'

Other comprehensive income (loss)

'

'

-78

'

'

'

'

'

'

-78

'

'

'

'

Net income (loss)

'

'

1,845

'

'

'

'

'

'

'

'

'

162

'

Ending balance at Dec. 31, 2011

'

'

30,081

'

'

'

'

'

'

-78

'

'

361

'

Other

-76

'

-88

'

4

'

'

'

'

'

'

-80

-84

'

Other comprehensive income (loss)

167

'

13

'

'

'

'

'

167

13

'

'

'

'

Net income (loss)

6,351

'

3,213

'

'

'

6,203

'

'

'

'

148

158

'

Ending balance at Dec. 31, 2012

'

32,254

32,254

'

'

'

'

'

'

-65

'

'

419

'

Other

210

'

275

'

152

'

'

'

'

'

'

58

111

'

Other comprehensive income (loss)

67

'

49

'

'

'

'

'

67

49

'

'

'

'

Net income (loss)

6,934

'

2,102

'

'

'

6,816

'

'

'

'

118

134

'

Ending balance at Dec. 31, 2013

'

$29,327

$29,327

'

'

'

'

'

'

($16)

'

'

$287

'

Business_and_Basis_of_Presenta

Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2013
Business and Basis of Presentation	'
	Note 1: Business and Basis of Presentation
	We are a global media and technology company with two primary businesses, Comcast Cable and NBCUniversal. We were incorporated under the laws of Pennsylvania in December 2001. Through our predecessors, we have developed, managed and operated cable systems since 1963. In 2011, we closed the NBCUniversal transaction in which we acquired control of the businesses of NBCUniversal Media, LLC (“NBCUniversal”), and in 2013, we acquired GE's remaining 49% common equity interest in NBCUniversal.
	We present our operations for Comcast Cable in one reportable business segment, referred to as Cable Communications, and our operations for NBCUniversal in four reportable business segments. The Cable Networks, Broadcast Television, Filmed Entertainment and Theme Parks segments comprise the NBCUniversal businesses and are collectively referred to as the NBCUniversal segments. See Note 19 for additional information on our reportable business segments.
	Our Cable Communications segment primarily manages and operates cable systems that serve residential and business customers in the United States. As of December 31, 2013, we served 21.7 million video customers, 20.7 million high-speed Internet customers and 10.7 million voice customers.
	Our Cable Networks segment consists primarily of a diversified portfolio of cable television networks. Our cable networks are comprised of our national cable networks, which provide a variety of entertainment, news and information and sports content, our regional sports and news networks, our international cable networks, and our cable television production operations.
	Our Broadcast Television segment consists primarily of the NBC and Telemundo broadcast networks, our NBC and Telemundo owned local television stations, and our broadcast television production operations.
	Our Filmed Entertainment segment primarily produces, acquires, markets and distributes filmed entertainment worldwide. Our films are produced primarily under the Universal Pictures, Focus Features and Illumination names.
	Our Theme Parks segment consists primarily of our Universal theme parks in Orlando and Hollywood. We also receive fees from third parties that own and operate Universal Studios Japan and Universal Studios Singapore for intellectual property licenses and other services.
	Our other business interests primarily include Comcast-Spectacor, which owns the Philadelphia Flyers and the Wells Fargo Center arena in Philadelphia and operates arena management-related businesses.
	Basis of Presentation
	The accompanying consolidated financial statements include all entities in which we have a controlling voting interest (“subsidiaries”) and variable interest entities (“VIEs”) required to be consolidated in accordance with generally accepted accounting principles in the United States (“GAAP”).
	We translate assets and liabilities of our foreign subsidiaries where the functional currency is the local currency, primarily the euro and the British pound, into U.S. dollars at the exchange rate in effect as of the balance sheet date. The related translation adjustments are recorded as a component of accumulated other comprehensive income (loss). We translate revenue and expenses using average monthly exchange rates, and the related foreign currency transaction gains and losses are included in our consolidated statement of income.
	Reclassifications
	Reclassifications have been made to our consolidated financial statements for the prior years to conform to classifications used in 2013.
NBCUniversal Media, LLC [Member]	'
Business and Basis of Presentation	'
	Notes to Consolidated Financial Statements
	Note 1: Business and Basis of Presentation
	We are one of the world's leading media and entertainment companies that develops, produces and distributes entertainment, news and information, sports, and other content for global audiences. In 2011, Comcast closed its transaction with General Electric Company (“GE”), in which Comcast acquired control of the businesses of NBCUniversal Media, LLC (“NBCUniversal”), and in 2013, Comcast acquired GE's remaining 49% common equity interest in our parent, NBCUniversal, LLC (“NBCUniversal Holdings”). See Note 3 for additional information on these transactions.
	We present our operations as the following four reportable business segments: Cable Networks, Broadcast Television, Filmed Entertainment and Theme Parks. See Note 18 for additional information on our reportable business segments.
	Our Cable Networks segment consists primarily of a diversified portfolio of cable television networks. Our cable networks are comprised of our national cable networks, which provide a variety of entertainment, news and information, and sports content, our regional sports and news networks, our international cable networks, and our cable television production operations.
	Our Broadcast Television segment consists primarily of the NBC and Telemundo broadcast networks, our NBC and Telemundo owned local television stations, and our broadcast television production operations.
	Our Filmed Entertainment segment primarily produces, acquires, markets and distributes filmed entertainment worldwide. Our films are produced primarily under the Universal Pictures, Focus Features and Illumination names.
	Our Theme Parks segment consists primarily of our Universal theme parks in Orlando and Hollywood. We also receive fees from third parties that own and operate Universal Studios Japan and Universal Studios Singapore for intellectual property licenses and other services.
	Basis of Presentation
	The accompanying consolidated financial statements include all entities in which we have a controlling voting interest (“subsidiaries”) and variable interest entities (“VIEs”) required to be consolidated in accordance with generally accepted accounting principles in the United States (“GAAP”). Transactions between NBCUniversal and Comcast, and their consolidated subsidiaries are reflected in these consolidated financial statements and disclosed as related party transactions when material.
	We translate assets and liabilities of our foreign subsidiaries where the functional currency is the local currency, primarily the euro and the British pound, into U.S. dollars at the exchange rate in effect as of the balance sheet date. The related translation adjustments are recorded as a component of accumulated other comprehensive income (loss). We translate revenue and expenses using average monthly exchange rates, and the related foreign currency transaction gains and losses are included in our consolidated statement of income.
	As a result of the change in control of our company on January 28, 2011, Comcast applied the acquisition method of accounting with respect to the assets and liabilities of the NBCUniversal businesses it acquired (“NBCUniversal contributed business”), which were remeasured to fair value as of the date of the Joint Venture transaction. Our consolidated financial statements for periods following the close of the Joint Venture transaction are labeled “Successor” and reflect both Comcast's basis of accounting in the new fair values of the assets and liabilities of the NBCUniversal contributed businesses and the consolidation of the Comcast Content Business at historical cost. All periods prior to the close of the Joint Venture transaction reflect the historical accounting basis in our assets and liabilities and are labeled “Predecessor.” Our consolidated financial statements and footnotes include a black line division, which appears between the columns titled Predecessor and Successor, which signifies that the amounts shown for the periods prior to and following the Joint Venture transaction are not comparable. See Note 3 for additional information on the Joint Venture transaction.
	Reclassifications
	Reclassifications have been made to our consolidated financial statements for the prior years to conform to classifications used in 2013.

Accounting_Policies

Accounting Policies	12 Months Ended
	Dec. 31, 2013
Accounting Policies	'
	Note 2: Accounting Policies
	Our consolidated financial statements are prepared in accordance with GAAP, which requires us to select accounting policies, including in certain cases industry-specific policies, and make estimates that affect the reported amount of assets, liabilities, revenue and expenses, and the related disclosure of contingent assets and contingent liabilities. Actual results could differ from these estimates. We believe the judgments and related estimates for the following items are critical in the preparation of our consolidated financial statements:
	valuation and impairment testing of cable franchise rights (see Note 8)
	film and television costs (see Note 5)
	income taxes (see Note 15)
	In addition, the following accounting policies are specific to the industries in which we operate:
	capitalization and amortization of film and television costs (see Note 5)
	customer installation costs in our Cable Communications segment (see Note 7)
	Information on our other accounting policies or methods related to our consolidated financial statements are included, where applicable, in their respective footnotes that follow. Below is a discussion of accounting policies and methods used in our consolidated financial statements that are not presented within other footnotes.
	Revenue Recognition
	Cable Communications Segment
	Our Cable Communications segment generates revenue primarily from subscriptions to our video, high-speed Internet and voice services (“cable services”) and from the sale of advertising. We recognize revenue from cable services as each service is provided. Customers are typically billed in advance on a monthly basis. We manage credit risk by screening applicants through the use of internal customer information, identification verification tools and credit bureau data. If a customer's account is delinquent, various measures are used to collect outstanding amounts, including termination of the customer's cable services. Since installation revenue obtained from the connection of customers to our cable systems is less than related direct selling costs, we recognize revenue as connections are completed.
	As part of our distribution agreements with cable networks, we generally receive an allocation of scheduled advertising time that we sell to local, regional and national advertisers. We recognize advertising revenue when the advertising is aired. In most cases, the available advertising time is sold by our sales force. In some cases, we work with representation firms as an extension of our sales force to sell a portion of the advertising time allocated to us. We also represent the advertising sales efforts of other multichannel video providers in some markets. Since we are acting as the principal in these arrangements, we report the advertising that is sold as revenue and the fees paid to representation firms and multichannel video providers as other operating and administrative expenses.
	Revenue earned from other sources is recognized when services are provided or events occur. Under the terms of our cable franchise agreements, we are generally required to pay to the franchising authority an amount based on our gross video revenue. We normally pass these fees through to our cable customers and classify the fees as a component of revenue with the corresponding costs included in other operating and administrative expenses.
	Cable Networks and Broadcast Television Segments
	Our Cable Networks segment generates revenue primarily from the distribution of our cable network programming to multichannel video providers, the sale of advertising and the licensing of our owned programming. Our Broadcast Television segment generates revenue primarily from the sale of advertising, the licensing of our owned programming and the fees received under retransmission consent agreements. We recognize revenue from distributors as programming is provided, generally under multiyear distribution agreements. From time to time, the distribution agreements expire while programming continues to be provided to the distributor based on interim arrangements while the parties negotiate new contract terms. Revenue recognition is generally limited to current payments being made by the distributor, typically under the prior contract terms, until a new contract is negotiated, sometimes with effective dates that affect prior periods. Differences between actual amounts determined upon resolution of negotiations and amounts recorded during these interim arrangements are recorded in the period of resolution.
	Advertising revenue for our Cable Networks and Broadcast Television segments is recognized in the period in which commercials are aired or viewed. In some instances, we guarantee viewer ratings for the commercials. To the extent there is a shortfall in the ratings that were guaranteed, a portion of the revenue is deferred until the shortfall is settled, primarily by providing additional advertising time. We record revenue from the licensing of our owned programming when the content is available for use by the licensee, and when certain other conditions are met. When license fees include advertising time, we recognize the advertising time component of revenue when the advertisements are aired or viewed.
	Filmed Entertainment Segment
	Our Filmed Entertainment segment generates revenue primarily from the worldwide distribution of our owned and acquired films for exhibition in movie theaters, the licensing of our owned and acquired films to cable, broadcast and premium networks and digital distributors, and the sale of our owned and acquired films on both standard-definition DVDs and Blu-ray discs (together, “DVDs”) and through digital distributors. We also generate revenue from producing and licensing live stage plays and distributing filmed entertainment produced by third parties. We recognize <>revenue from the distribution of films to movie theaters when the films are exhibited. We record revenue from the licensing of a film when the film is available for use by the licensee, and when certain other conditions are met. We recognize revenue from DVD sales, net of estimated returns and customer incentives, on the date that DVDs are delivered to and made available for sale by retailers.
	Theme Parks Segment
	Our Theme Parks segment generates revenue primarily from theme park attendance and per capita spending at our Universal theme parks in Orlando and Hollywood, as well as from licensing and other fees. We recognize <>revenue from advance theme park ticket sales when the tickets are used. For annual passes, we recognize revenue on a straight-line basis over the annual period following the initial redemption date.
	Cable Communications Programming Expenses
	Cable Communications programming expenses are the fees we pay to license the programming we distribute to our video customers. Programming is acquired for distribution to our video customers, generally under multiyear distribution agreements, with rates typically based on the number of customers that receive the programming, adjusted for channel positioning and the extent of distribution. From time to time these contracts expire and programming continues to be provided under interim arrangements while the parties negotiate new contractual terms, sometimes with effective dates that affect prior periods. While payments are typically made under the prior contract's terms, the amount of programming expenses recorded during these interim arrangements is based on our estimates of the ultimate contractual terms expected to be negotiated. Differences between actual amounts determined upon resolution of negotiations and amounts recorded during these interim arrangements are recorded in the period of resolution.
	When our Cable Communications segment receives incentives from cable networks for the licensing of their programming, we defer a portion of these incentives, which are included in other current and noncurrent liabilities, and recognize them over the term of the contract as a reduction to programming and production expenses.
	Advertising Expenses
	Advertising costs are expensed as incurred.
	Cash Equivalents
	The carrying amounts of our cash equivalents approximate their fair value. Our cash equivalents consist primarily of money market funds and U.S. government obligations, as well as commercial paper and certificates of deposit with maturities of less than three months when purchased.
	Derivative Financial Instruments
	We use derivative financial instruments to manage our exposure to the risks associated with fluctuations in interest rates, foreign exchange rates and equity prices. Our objective is to manage the financial and operational exposure arising from these risks by offsetting gains and losses on the underlying exposures with gains and losses on the derivatives used to economically hedge them.
	Our derivative financial instruments are recorded on our consolidated balance sheet at fair value. See Note 6 for additional information on the derivative component of our prepaid forward sale agreements. The impact of our other derivative financial instruments on our consolidated financial statements was not material for all periods presented.
	Asset Retirement Obligations
	Certain of our cable franchise agreements and lease agreements contain provisions requiring us to restore facilities or remove property in the event that the franchise or lease agreement is not renewed. We expect to continually renew our cable franchise agreements and therefore cannot reasonably estimate any liabilities associated with such agreements. A remote possibility exists that franchise agreements could be terminated unexpectedly, which could result in us incurring significant expense in complying with restoration or removal provisions. The disposal obligations related to our properties are not material to our consolidated financial statements. We do not have any significant liabilities related to asset retirements recorded in our consolidated financial statements.
NBCUniversal Media, LLC [Member]	'
Accounting Policies	'
	Note 2: Accounting Policies
	Our consolidated financial statements are prepared in accordance with GAAP, which requires us to select accounting policies, including in certain cases industry-specific policies, and make estimates that affect the reported amount of assets, liabilities, revenue and expenses, and the related disclosure of contingent assets and contingent liabilities. Actual results could differ from these estimates. We believe the judgments and related estimates for the following items are critical in the preparation of our consolidated financial statements:
	revenue recognition (see below)
	film and television costs (see Note 5)
	goodwill and intangible assets (see Note 8)
	fair value of contractual obligations (see Note 10)
	In addition, the following accounting policies are specific to the industries in which we operate:
	capitalization and amortization of film and television costs (see Note 5)
	Information on our other accounting policies or methods related to our consolidated financial statements are included, where applicable, in their respective footnotes that follow. Below is a discussion of accounting policies and methods used in our consolidated financial statements that are not presented within other footnotes.
	Revenue Recognition
	Cable Networks and Broadcast Television Segments
	Our Cable Networks segment generates revenue primarily from the distribution of our cable network programming to multichannel video providers, the sale of advertising and the licensing of our owned programming. Our Broadcast Television segment generates revenue primarily from the sale of advertising, the licensing of our owned programming and the fees received under retransmission consent agreements. We recognize revenue from distributors as programming is provided, generally under multiyear distribution agreements. From time to time, the distribution agreements expire while programming continues to be provided to the distributor based on interim arrangements while the parties negotiate new contract terms. Revenue recognition is generally limited to current payments being made by the distributor, typically under the prior contract terms, until a new contract is negotiated, sometimes with effective dates that affect prior periods. Differences between actual amounts determined upon resolution of negotiations and amounts recorded during these interim arrangements are recorded in the period of resolution.
	Advertising revenue for our Cable Networks and Broadcast Television segments is recognized in the period in which commercials are aired or viewed. In some instances, we guarantee viewer ratings for the commercials. To the extent there is a shortfall in the ratings that were guaranteed, a portion of the revenue is deferred until the shortfall is settled, primarily by providing additional advertising time. We record revenue from the licensing of our owned programming when the content is available for use by the licensee, and when certain other conditions are met. When license fees include advertising time, we recognize the advertising time component of revenue when the advertisements are aired or viewed.
	Filmed Entertainment Segment
	Our Filmed Entertainment segment generates revenue primarily from the worldwide distribution of our owned and acquired films for exhibition in movie theaters, the licensing of our owned and acquired films to cable, broadcast and premium networks and digital distributors, and the sale of our owned and acquired films on both standard-definition DVDs and Blu-ray discs (together, “DVDs”) and through digital distributors. We also generate revenue from producing and licensing live stage plays and distributing filmed entertainment produced by third parties. We recognize <>revenue from the distribution of films to movie theaters when the films are exhibited. We record revenue from the licensing of a film when the film is available for use by the licensee, and when certain other conditions are met. We recognize revenue from DVD sales, net of estimated returns and customer incentives, on the date that DVDs are delivered to and made available for sale by retailers.
	Theme Parks Segment
	Our Theme Parks segment generates revenue primarily from theme park attendance and per capita spending at our Universal theme parks in Orlando and Hollywood, as well as from licensing and other fees. We recognize <>revenue from advance theme park ticket sales when the tickets are used. For annual passes, we recognize revenue on a straight-line basis over the annual period following the initial redemption date.
	Advertising Expenses
	Advertising costs are expensed as incurred.
	Cash Equivalents
	The carrying amounts of our cash equivalents approximate their fair value. Our cash equivalents consist primarily of money market funds and U.S. government obligations, as well as commercial paper and certificates of deposit with maturities of less than three months when purchased.
	Derivative Financial Instruments
	We use derivative financial instruments to manage our exposure to the risks associated with fluctuations in foreign exchange rates and interest rates. Our objective is to manage the financial and operational exposure arising from these risks by offsetting gains and losses on the underlying exposures with gains and losses on the derivatives used to economically hedge them.
	Our derivative financial instruments are recorded on our consolidated balance sheet at fair value. The impact of our derivative financial instruments on our consolidated financial statements was not material for all periods presented.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2013
Earnings Per Share	'
	Note 3: Earnings Per Share
	Computation of Diluted EPS
			2013					2012					2011
	Year ended December 31 (in millions, except per share data)		Net Income Attributable to Comcast Corporation	Shares		Per Share Amount		Net Income Attributable to Comcast Corporation	Shares		Per Share Amount		Net Income Attributable to Comcast Corporation	Shares		Per Share Amount
	Basic EPS attributable to Comcast Corporation shareholders	$	6,816	2,625	$	2.6	$	6,203	2,678	$	2.32	$	4,160	2,746	$	1.51
	Effect of dilutive securities:
	Assumed exercise or issuance of shares relating to stock plans			40					39					32
	Diluted EPS attributable to Comcast Corporation shareholders	$	6,816	2,665	$	2.56	$	6,203	2,717	$	2.28	$	4,160	2,778	$	1.5
	Our potentially dilutive securities include potential common shares related to our stock options and our restricted share units (“RSUs”). Diluted earnings per common share attributable to Comcast Corporation shareholders (“diluted EPS”) considers the impact of potentially dilutive securities using the treasury stock method. Diluted EPS excludes the impact of potential common shares related to our stock options in periods in which the combination of the option exercise price and the associated unrecognized compensation expense is greater than the average market price of our Class A common stock or our Class A Special common stock, as applicable.
	Diluted EPS for 2011 excluded 45 million of potential common shares related to our share-based compensation plans, because the inclusion of the potential common shares would have had an antidilutive effect. These amounts were not material for 2013 and 2012.

Significant_Transactions

Significant Transactions	12 Months Ended
	Dec. 31, 2013
Significant Transactions	'
	Note 4: Significant Transactions
	2013
	Redemption Transaction
	On March 19, 2013, we acquired GE's remaining 49% common equity interest in NBCUniversal, LLC (“NBCUniversal Holdings”) for approximately $16.7 billion (the “Redemption Transaction”). In addition to this transaction, NBCUniversal purchased from GE certain properties NBCUniversal occupies at 30 Rockefeller Plaza in New York City and CNBC's headquarters in Englewood Cliffs, New Jersey for $1.4 billion.
	The total consideration for these transactions consisted of $11.4 billion of cash on hand; $4 billion of senior debt securities issued by NBCUniversal Enterprise, Inc. (“NBCUniversal Enterprise”), a holding company that we control and consolidate following the close of the Redemption Transaction whose principal assets are its interests in NBCUniversal Holdings; $750 million of cash funded through our commercial paper program; $1.25 billion of borrowings under NBCUniversal Enterprise's credit facility, which replaced NBCUniversal's credit facility; and $725 million aggregate liquidation preference of Series A cumulative preferred stock of NBCUniversal Enterprise. See Note 9 for additional information on NBCUniversal Enterprise's senior debt securities and credit facility and Note 21 for additional information on our cross-guarantee structure.
	The NBCUniversal Enterprise preferred stock is now held by unaffiliated third parties and pays dividends at a fixed rate of 5.25% per annum. The holders have the right to cause NBCUniversal Enterprise to redeem their shares at a price equal to the liquidation preference plus accrued but unpaid dividends for a 30 day period beginning on March 19, 2020 and thereafter on every third anniversary of such date (each such date, a “put date”). Shares of preferred stock can be called for redemption by NBCUniversal Enterprise at a price equal to the liquidation preference plus accrued but unpaid dividends one year following each put date applicable to such shares. Because certain of these redemption provisions are outside of our control, the NBCUniversal Enterprise preferred stock is presented outside of equity under the caption “redeemable noncontrolling interests and redeemable subsidiary preferred stock” in our consolidated balance sheet. Its initial value was based on the liquidation preference of the preferred stock and is adjusted for accrued but unpaid dividends. As of December 31, 2013, the fair value of the redeemable subsidiary preferred stock was $741 million. The estimated fair value was based on Level 2 inputs using pricing models whose inputs are derived primarily from or corroborated by observable market data through correlation or other means for substantially the full term of the financial instrument.
	We recognized an increase to our deferred tax liabilities of $1.6 billion primarily due to an increase in our financial reporting basis in the consolidated net assets of NBCUniversal Holdings in excess of the tax basis following the Redemption Transaction. In addition, our consolidated balance sheet now includes certain tax liabilities of NBCUniversal Enterprise related to periods prior to our acquisition of the common stock of NBCUniversal Enterprise for which we have been indemnified by GE and have recorded a related indemnification asset. We also expect to realize additional tax benefits in the future as a result of the Redemption Transaction, which are expected to increase the amounts we have agreed to share with GE. Our expected future payments to GE are accounted for as contingent consideration. See Note 10 for additional information on the fair value of this contingent consideration as of December 31, 2013.
	Because we maintained control of NBCUniversal Holdings, the difference between the consideration transferred and the recorded value of GE's 49% redeemable noncontrolling common equity interest, and the related tax impacts, were recorded to additional paid-in capital.
	2011
	NBCUniversal Transaction
	On January 28, 2011, we closed our transaction with GE in which we acquired a 51% controlling interest in NBCUniversal Holdings. As part of the NBCUniversal transaction, GE contributed the businesses of NBCUniversal, which is a wholly owned subsidiary of NBCUniversal Holdings. We contributed our national cable networks, our regional sports and news networks, certain of our Internet businesses and other related assets (the “Comcast Content Business”). In addition to contributing the Comcast Content Business, we also made a cash payment to GE of $6.2 billion, which included transaction-related costs.
	In 2011, we recorded $10.9 billion of goodwill in our allocation of purchase price for the NBCUniversal transaction, which was allocated to our Cable Networks and Broadcast Television segments. Due to the partnership structure of NBCUniversal Holdings, goodwill related to the NBCUniversal transaction is not deductible for tax purposes. In addition, we also recorded $576 million of deferred tax liabilities in connection with the NBCUniversal transaction, as well as an additional $35 million of net deferred income tax liabilities in the allocation of purchase price. See Note 15 for additional information on the partnership structure of NBCUniversal Holdings and NBCUniversal and other related income tax matters.
	Because we maintained control of the Comcast Content Business, the excess of the fair value received over the historical book value and the related tax impact were recorded to additional paid-in capital.
	We agreed to share with GE certain tax benefits as they are realized that relate to the form and structure of the transaction. These payments to GE are contingent on us realizing tax benefits in the future and are accounted for as contingent consideration. See Note 10 for additional information on our contingent consideration liability.
	Universal Orlando Transaction
	On July 1, 2011, NBCUniversal acquired the remaining 50% equity interest in Universal Orlando that it did not already own for $1 billion. Following the close of the transaction, Universal Orlando is a wholly owned consolidated subsidiary of NBCUniversal, and its operations are reported in our Theme Parks segment. We recorded $982 million of goodwill in our allocation of purchase price for this transaction, which was fully allocated to our Theme Parks segment.
NBCUniversal Media, LLC [Member]	'
Significant Transactions	'
	Note 3: Significant Transactions
	2013
	Redemption Transaction
	On March 19, 2013, Comcast acquired GE's remaining 49% common equity interest in NBCUniversal Holdings for approximately $16.7 billion (the “Redemption Transaction”). In addition to this transaction, we purchased from GE certain properties we occupy at 30 Rockefeller Plaza in New York City and CNBC's headquarters in Englewood Cliffs, New Jersey for $1.4 billion.
	The total consideration for these transactions consisted of $11.4 billion of cash on hand (of which we funded $4.6 billion); $4 billion of senior debt securities issued by NBCUniversal Enterprise, Inc. (“NBCUniversal Enterprise”), a holding company whose principal assets are its interests in NBCUniversal Holdings; $750 million of cash funded through Comcast's commercial paper program; $1.25 billion of borrowings under NBCUniversal Enterprise's credit facility, which replaced our credit facility; and $725 million aggregate liquidation preference of Series A cumulative preferred stock of NBCUniversal Enterprise. After the close of the transaction, GE sold the interests in NBCUniversal Enterprise's senior debt securities and preferred stock it acquired in the Redemption Transaction to unaffiliated third parties.
	Following the close of the Redemption Transaction, Comcast owns 96% of NBCUniversal Holdings' common units and NBCUniversal Enterprise owns the remaining 4%. NBCUniversal Enterprise is now a consolidated subsidiary of Comcast, but we do not have any ownership interests in NBCUniversal Enterprise. NBCUniversal Enterprise also owns all of NBCUniversal Holdings' preferred units with a $9.4 billion aggregate liquidation preference. NBCUniversal Holdings is required to make quarterly payments to NBCUniversal Enterprise at an initial rate of 8.25% per annum on the $9.4 billion aggregate liquidation preference of the preferred units. On March 1, 2018, and thereafter on every fifth anniversary of such date, this rate will reset to 7.44% plus the yield on actively traded United States Treasury securities having a 5 year maturity. NBCUniversal Holdings has the right to redeem all of the preferred units during the 30 day period beginning on March 1, 2018, and NBCUniversal Enterprise has the right to cause NBCUniversal Holdings to redeem 15% of its preferred units during the 30 day period beginning on March 19, 2020. The price and units in a redemption initiated by either party will be based on the liquidation preference plus accrued but unpaid dividends and adjusted, in the case of an exercise of NBCUniversal Enterprise's right, to the extent the equity value of NBCUniversal Holdings is less than the liquidation preference. Our cash flows are, and will continue to be, the primary source of funding for the required payments and any future redemption of the NBCUniversal Holdings preferred units.
	2011
	Joint Venture Transaction
	On January 28, 2011, Comcast and GE closed the Joint Venture transaction, which among other things, converted our company into a limited liability company that became a wholly owned subsidiary of NBCUniversal Holdings. NBCUniversal comprises the NBCUniversal contributed businesses and the Comcast Content Business. In addition to contributing the Comcast Content Business to NBCUniversal, Comcast made a cash payment to GE of $6.2 billion, which included transaction-related costs. Comcast also agreed to share with GE certain tax benefits as they are realized that relate to the form and structure of the Joint Venture transaction. These payments to GE are contingent on Comcast realizing tax benefits in the future and are accounted for as contingent consideration by Comcast.
	Universal Orlando Transaction
	On July 1, 2011, we acquired the remaining 50% equity interest in Universal Orlando that we did not already own for $1 billion. Following the close of the transaction, Universal Orlando is a wholly owned consolidated subsidiary, and its operations are reported in our Theme Parks segment. We recorded $982 million of goodwill in our allocation of purchase price for this transaction, which was fully allocated to our Theme Parks segment.

Related_Party_Transactions

Related Party Transactions (NBCUniversal Media, LLC [Member])	12 Months Ended
	Dec. 31, 2013
NBCUniversal Media, LLC [Member]	'
Related Party Transactions	'
	Note 4: Related Party Transactions
	In the ordinary course of our business, we enter into transactions with Comcast.
	We generate revenue from Comcast primarily from the distribution of our cable network programming and, to a lesser extent, the sale of advertising and our owned programming, and we incur expenses primarily related to various support services provided by Comcast to us.
	On March 19, 2013, as part of the Comcast cash management process, we and Comcast entered into a revolving credit agreement under which we can borrow up to $3 billion from Comcast and Comcast can borrow up to $3 billion from us. Amounts owed by us to Comcast under the revolving credit agreement, including accrued interest, are presented under the caption “note payable to Comcast” in our consolidated balance sheet. The revolving credit agreements bear interest at floating rates equal to the interest rate under the Comcast and Comcast Cable Communications, LLC revolving credit facility (the “Comcast revolving credit facility”). The interest rate on the Comcast revolving credit facility consists of a base rate plus a borrowing margin that is determined based on Comcast's credit rating. As of December 31, 2013, the borrowing margin for London Interbank Offered Rate based borrowings was 1.00%.
	In addition, Comcast is the counterparty to one of our contractual obligations. As of December 31, 2013, the carrying value of the liability associated with this contractual obligation was $383 million. See Note 10 for additional information on this contractual obligation.
	The following tables present transactions with Comcast and its consolidated subsidiaries that are included in our consolidated financial statements.
	Consolidated Balance Sheet
					Successor
	December 31 (in millions)			2013			2012
	Transactions with Comcast and consolidated subsidiaries
		Receivables, net		$	228		$	204
		Accounts payable and accrued expenses related to trade creditors		$	56		$	25
		Accrued expenses and other current liabilities		$	37		$	1
		Note payable to Comcast		$	799		$	-
		Other noncurrent liabilities		$	383		$	-
	Consolidated Statement of Income
				Successor
	(in millions)			Year Ended December 31, 2013		Year Ended December 31, 2012		For the Period January 29, 2011 to December 31, 2011
	Transactions with Comcast and consolidated subsidiaries
		Revenue	$	1,262	$	1,228	$	1,025
		Operating costs and expenses	$	-190	$	-175	$	-72
	Distributions to NBCUniversal Holdings
	In addition to the transactions above, we make distributions to NBCUniversal Holdings on a periodic basis to enable its owners to meet their obligations to pay taxes on taxable income generated by our businesses. We also make quarterly distributions to NBCUniversal Holdings to enable it to make its required quarterly payments to NBCUniversal Enterprise at an initial annual rate of 8.25% on the $9.4 billion aggregate liquidation preference of its preferred units. These distributions are presented under the caption “distributions to member” in our consolidated statement of cash flows. Following the close of the Redemption Transaction, none of these distributions to NBCUniversal Holdings are attributable to GE.
	In connection with the Redemption Transaction, we also made a distribution of $3.2 billion to NBCUniversal Holdings to fund a portion of the Redemption Transaction. This distribution is presented separately in our consolidated statement of cash flows.
	Transactions with GE
	Following the close of the Redemption Transaction and the subsequent sale of NBCUniversal Enterprise's preferred stock and senior notes by GE to unaffiliated third parties in March 2013, we no longer consider GE to be a related party.
	In February 2013, Comcast closed an agreement with GE, General Electric Capital Corporation (“GECC”) and LIN TV under which, among other things, we purchased a note held by Station Venture Holdings, LLC (“Station Venture”) from GECC for $602 million, which effectively settled a liability of $482 million that had been recorded in the allocation of purchase price associated with the Joint Venture transaction. Due to the related party nature of this transaction, the excess of the purchase price of the Station Venture note over the recorded amount of the liability was recorded to member's capital. Other than the Station Venture transaction, dividend payments to GE that are included under the caption “dividends” on our consolidated statement of changes in equity and our consolidated statement of cash flows, and the transactions discussed in Note 3, the amounts related to our transactions with GE and its consolidated subsidiaries that occurred prior to the close of the Redemption Transaction were not material.

Film_and_Television_Costs

Film and Television Costs	12 Months Ended
	Dec. 31, 2013
Film And Television Costs Disclosure [Text Block]	'
	Note 5: Film and Television Costs
	December 31 (in millions)			2013		2012
	Film Costs:
		Released, less amortization	$	1,630	$	1,472
		Completed, not released		70		99
		In production and in development		658		1,048
				2,358		2,619
	Television Costs:
		Released, less amortization		1,155		1,124
		In production and in development		370		334
				1,525		1,458
	Programming rights, less amortization			2,039		1,886
				5,922		5,963
	Less: Current portion of programming rights			928		909
	Film and television costs		$	4,994	$	5,054
	Based on our estimates of the ratio of the current period's actual revenue to the estimated total remaining gross revenue from all sources (“ultimate revenue”), as of December 31, 2013, approximately $ 1.3 billion of film and television costs associated with our original film and television productions that have been released, or completed and not yet released, are expected to be amortized during 2014. Approximately 85% of unamortized film and television costs for our released productions, excluding amounts allocated to acquired libraries, are expected to be amortized through 2016.
	As of December 31, 2013, acquired film and television libraries, which are included within the “released, less amortization” captions in the table above, had remaining unamortized costs of $711 million. These costs are generally amortized over a period not to exceed 20 years, and approximately 49% of these costs are expected to be amortized through 2016.
	Capitalization of Film and Television Costs
	We capitalize film and television production costs, including direct costs, production overhead, print costs, development costs and interest. We amortize capitalized film and television production costs, including acquired libraries, and accrue costs associated with participation and residual payments to programming and production expense. We generally record the amortization and the accrued costs using the individual film forecast computation method, which amortizes such costs in the same ratio as the associated ultimate revenue. Estimates of total revenue and total costs are based on anticipated release patterns, public acceptance and historical results for similar productions. Unamortized film and television costs, including acquired film and television libraries, are stated at the lower of unamortized cost or fair value. We do not capitalize costs related to the distribution of a film to movie theaters or the licensing or sale of a film or television production, which are primarily costs associated with the marketing and distribution of film and television programming.
	In determining the estimated lives and method of amortization of acquired film and television libraries, we generally use the method and the life that most closely follow the undiscounted cash flows over the estimated life of the asset.
	Upon the occurrence of an event or a change in circumstance that was known or knowable as of the balance sheet date and that indicates the fair value of a film is less than its unamortized costs, we determine the fair value of the film and record an impairment charge for the amount by which the unamortized capitalized costs exceed the film's fair value.
	We enter into arrangements with third parties to jointly finance and distribute certain of our film productions. These arrangements, which are referred to as cofinancing arrangements, can take various forms. In most cases, the arrangement involves the grant of an economic interest in a film to a third-party investor. The number of investors and the terms of these arrangements can vary, although in most cases an investor assumes full risk for the portion of the film acquired in these arrangements. We account for the proceeds received from a third-party investor under these arrangements as a reduction to our capitalized film costs. In these arrangements, the investor owns an undivided copyright interest in the film and, therefore, in each period we record either a charge or a benefit to programming and production expense to reflect the estimate of the third-party investor's interest in the profit or loss of the film. The estimate of the third-party investor's interest in the profit or loss of a film is determined using the ratio of actual revenue earned to date to the ultimate revenue expected to be recognized over the film's useful life.
	We capitalize the costs of programming content that we license but do not own, including rights to multiyear live-event sports programming, at the earlier of when payments are made for the programming or when the license period begins and the content is available for use. We amortize capitalized programming costs as the associated programs are broadcast. We amortize multiyear, live-event sports programming rights using the ratio of the current period revenue to the estimated total remaining revenue or under the terms of the contract.
	Acquired programming costs are recorded at the lower of unamortized cost or net realizable value on a program by program, package, channel or daypart basis. A daypart is an aggregation of programs broadcast during a particular time of day or programs of a similar type. Acquired programming used in our Cable Networks segment is primarily tested on a channel basis for impairment, whereas acquired programming used in our Broadcast Television segment is tested on a daypart basis. If we determine that the estimates of future cash flows are insufficient or if there is no plan to broadcast certain programming, we recognize an impairment charge to programming and production expense.
NBCUniversal Media, LLC [Member]	'
Film And Television Costs Disclosure [Text Block]	'
	Note 5: Film and Television Costs
				Successor
	December 31 (in millions)			2013		2012
	Film Costs:
		Released, less amortization	$	1,630	$	1,472
		Completed, not released		70		99
		In production and in development		658		1,048
				2,358		2,619
	Television Costs:
		Released, less amortization		1,155		1,124
		In production and in development		370		334
				1,525		1,458
	Programming rights, less amortization			2,003		1,808
				5,886		5,885
	Less: Current portion of programming rights			903		844
	Film and television costs		$	4,983	$	5,041
	Based on our estimates of the ratio of the current period's actual revenue to the estimated total remaining gross revenue from all sources (“ultimate revenue”), as of December 31, 2013, approximately $ 1.3 billion of film and television costs associated with our original film and television productions that have been released, or completed and not yet released, are expected to be amortized during 2014. Approximately 85% of unamortized film and television costs for our released productions, excluding amounts allocated to acquired libraries, are expected to be amortized through 2016.
	As of December 31, 2013, acquired film and television libraries, which are included within the “released, less amortization” captions in the table above, had remaining unamortized costs of $711 million. These costs are generally amortized over a period not to exceed 20 years, and approximately 49% of these costs are expected to be amortized through 2016.
	Capitalization of Film and Television Costs
	We capitalize film and television production costs, including direct costs, production overhead, print costs, development costs and interest. We amortize capitalized film and television production costs, including acquired libraries, and accrue costs associated with participation and residual payments to programming and production expense. We generally record the amortization and the accrued costs using the individual film forecast computation method, which amortizes such costs in the same ratio as the associated ultimate revenue. Estimates of total revenue and total costs are based on anticipated release patterns, public acceptance and historical results for similar productions. Unamortized film and television costs, including acquired film and television libraries, are stated at the lower of unamortized cost or fair value. We do not capitalize costs related to the distribution of a film to movie theaters or the licensing or sale of a film or television production, which are primarily costs associated with the marketing and distribution of film and television programming.
	In determining the estimated lives and method of amortization of acquired film and television libraries, we generally use the method and the life that most closely follow the undiscounted cash flows over the estimated life of the asset.
	Upon the occurrence of an event or a change in circumstance that was known or knowable as of the balance sheet date and that indicates the fair value of a film is less than its unamortized costs, we determine the fair value of the film and record an impairment charge for the amount by which the unamortized capitalized costs exceed the film's fair value.
	We enter into arrangements with third parties to jointly finance and distribute certain of our film productions. These arrangements, which are referred to as cofinancing arrangements, can take various forms. In most cases, the arrangement involves the grant of an economic interest in a film to a third-party investor. The number of investors and the terms of these arrangements can vary, although in most cases an investor assumes full risk for the portion of the film acquired in these arrangements. We account for the proceeds received from a third-party investor under these arrangements as a reduction to our capitalized film costs. In these arrangements, the investor owns an undivided copyright interest in the film and, therefore, in each period we record either a charge or a benefit to programming and production expense to reflect the estimate of the third-party investor's interest in the profit or loss of the film. The estimate of the third-party investor's interest in the profit or loss of a film is determined using the ratio of actual revenue earned to date to the ultimate revenue expected to be recognized over the film's useful life.
	We capitalize the costs of programming content that we license but do not own, including rights to multiyear live-event sports programming, at the earlier of when payments are made for the programming or when the license period begins and the content is available for use. We amortize capitalized programming costs as the associated programs are broadcast. We amortize multiyear, live-event sports programming rights using the ratio of the current period revenue to the estimated total remaining revenue or under the terms of the contract.
	Acquired programming costs are recorded at the lower of unamortized cost or net realizable value on a program by program, package, channel or daypart basis. A daypart is an aggregation of programs broadcast during a particular time of day or programs of a similar type. Acquired programming used in our Cable Networks segment is primarily tested on a channel basis for impairment, whereas acquired programming used in our Broadcast Television segment is tested on a daypart basis. If we determine that the estimates of future cash flows are insufficient or if there is no plan to broadcast certain programming, we recognize an impairment charge to programming and production expense.

Investments

Investments	12 Months Ended
	Dec. 31, 2013
Investments	'
	Note 6: Investments
	December 31 (in millions)			2013		2012
	Fair Value Method		$	4,345	$	4,493
	Equity Method:
		The Weather Channel		333		471
		Hulu		187		-
		Other		469		693
				989		1,164
	Cost Method:
		AirTouch		1,553		1,538
		Other		456		594
				2,009		2,132
	Total investments			7,343		7,789
	Less: Current investments			3,573		1,464
	Noncurrent investments		$	3,770	$	6,325
	Investment Income (Loss), Net
	Year ended December 31 (in millions)			2013		2012		2011
	Gains on sales and exchanges of investments, net		$	484	$	30	$	41
	Investment impairment losses			-29		-24		-5
	Unrealized gains (losses) on securities underlying prepaid forward sale agreements			1,601		1,159		192
	Mark to market adjustments on derivative component of prepaid forward sale
		agreements and indexed debt instruments		-1,604		-1,071		-119
	Interest and dividend income			111		119		110
	Other, net			13		6		-60
	Investment income (loss), net		$	576	$	219	$	159
	Fair Value Method
	We classify publicly traded investments that are not accounted for under the equity method as available-for-sale (“AFS”) or trading securities and record them at fair value. For AFS securities, we record unrealized gains or losses resulting from changes in fair value between measurement dates as a component of other comprehensive income (loss), except when we consider declines in value to be other than temporary. For trading securities, we record unrealized gains or losses resulting from changes in fair value between measurement dates as a component of investment income (loss), net. We recognize realized gains and losses associated with our fair value method investments using the specific identification method. We classify the cash flows related to purchases of and proceeds from the sale of trading securities based on the nature of the securities and the purpose for which they were acquired.
	As of December 31, 2013 and 2012, the majority of our fair value method investments were equity securities that we account for as trading securities and were held as collateral related to our obligations under prepaid forward sale agreements.
	Prepaid Forward Sale Agreements
	December 31 (in millions)			2013		2012
	Assets:
		Fair value equity securities held as collateral	$	3,959	$	4,143
	Liabilities:
		Obligations under prepaid forward sale agreements	$	811	$	1,248
		Derivative component of prepaid forward sale agreements		2,800		2,302
	Total liabilities		$	3,611	$	3,550
	During 2013, we purchased a total of $657 million of equity securities classified as trading securities and held them as collateral under our prepaid forward sale agreements. We also settled obligations under certain of our prepaid forward sale agreements totaling $1.6 billion with a combination of cash on hand and $1.4 billion of equity securities. The majority of our remaining obligations related to these investments mature in 2014. At maturity, the counterparties are entitled to receive some or all of the equity securities, or an equivalent amount of cash at our option, based on the market value of the equity securities at that time. As of both December 31, 2013 and 2012, our prepaid forward sale obligations had an estimated fair value of $3.6 billion. The estimated fair values are based on Level 2 inputs using pricing models whose inputs are derived primarily from or corroborated by observable market data through correlation or other means for substantially the full term of the financial instrument.
	The derivative component of the prepaid forward sale agreements are equity derivative financial instruments embedded in the related contracts, which we use to manage our exposure to and benefits from price fluctuations in the common stock of the related investments. For these derivative financial instruments, we separate the derivative component from the host contract and record the change in its value each period to investment income (loss), net.
	Liberty Media
	In October 2013, Liberty Media Corporation (“Liberty Media”) redeemed 6.3 million shares of Liberty Media Series A common stock (“Liberty stock”) that had been held by us as collateral as of December 31, 2012 under certain of our prepaid forward sale agreements in exchange for all of the equity of a subsidiary of Liberty Media. The fair value of the Liberty stock at the date of the close of the transaction was $937 million. The assets of the subsidiary of Liberty Media included cash of $417 million, Liberty Media's interests in one of NBCUniversal's contractual obligations and a wholly owned operating subsidiary, Leisure Arts, Inc. Following the close of this transaction, we now consolidate the subsidiary transferred to us, and the liability associated with NBCUniversal's contractual obligation is eliminated in consolidation.
	Clearwire LLC
	In July 2013, in connection with Sprint Communications, Inc.'s (“Sprint”) acquisition of Clearwire Corporation (“Clearwire”), Sprint acquired our investment of 89 million Class A shares of Clearwire for $443 million. As a result, we recognized a pretax gain of $443 million in our consolidated statement of income, which represented the recognition of cumulative unrealized gains previously recorded in accumulated other comprehensive income (loss).
	Equity Method
	We use the equity method to account for investments in which we have the ability to exercise significant influence over the investee's operating and financial policies or where we hold significant partnership or LLC interests. Equity method investments are recorded at cost and are adjusted to recognize (i) our proportionate share of the investee's net income or losses after the date of investment, (ii) amortization of the recorded investment that exceeds our share of the book value of the investee's net assets, (iii) additional contributions made and dividends received and (iv) impairments resulting from other-than-temporary declines in fair value. For some investments, we record our share of the investee's net income or loss one quarter in arrears due to the timing of our receipt of such information. Gains or losses on the sale of equity method investments are recorded to other income (expense), net. If an equity method investee were to issue additional securities that would change our proportionate share of the entity, we would recognize the change, if any, as a gain or loss in our consolidated statement of income.
	The Weather Channel
	In June 2013, we received a distribution from The Weather Channel Holding Corp. (“The Weather Channel”) of $152 million, of which $128 million was recorded as a return of its investment in The Weather Channel and included under the caption “return of capital from investees” in our consolidated statement of cash flows.
	Hulu
	In July 2013, we entered into an agreement to provide capital contributions totaling $247 million to Hulu, LLC (“Hulu”), which we had previously accounted for as a cost method investment. This represented an agreement to provide our first capital contribution to Hulu since our interest was acquired as part of the NBCUniversal transaction, therefore we began to apply the equity method of accounting for this investment. The change in the method of accounting for this investment required us to recognize our proportionate share of Hulu's accumulated losses from the date of the NBCUniversal transaction through July 2013.
	Cost Method
	We use the cost method to account for investments not accounted for under the fair value method or the equity method.
	AirTouch Communications, Inc.
	We hold two series of preferred stock of AirTouch Communications, Inc. (“AirTouch”), a subsidiary of Vodafone, which are redeemable in April 2020. As of December 31, 2013 and 2012, the estimated fair value of the AirTouch preferred stock was $1.7 billion and $1.8 billion, respectively.
	The dividend and redemption activity of the AirTouch preferred stock determines the dividend and redemption payments associated with substantially all of the preferred shares issued by one of our consolidated subsidiaries, which is a VIE. The subsidiary has three series of preferred stock outstanding with an aggregate redemption value of $1.75 billion. Substantially all of the preferred shares are redeemable in April 2020 at a redemption value of $1.65 billion. As of both December 31, 2013 and 2012, the two redeemable series of subsidiary preferred shares were recorded at $1.5 billion, and those amounts are included in other noncurrent liabilities. As of December 31, 2013 and 2012, these redeemable subsidiary preferred shares had an estimated fair value of $1.7 billion and $1.8 billion, respectively. The estimated fair values are based on Level 2 inputs using pricing models whose inputs are derived primarily from or corroborated by observable market data through correlation or other means for substantially the full term of the financial instrument. The one nonredeemable series of subsidiary preferred shares was recorded at $100 million as of both December 31, 2013 and 2012, and those amounts are included in noncontrolling interests in our consolidated balance sheet. The carrying amounts of the nonredeemable subsidiary preferred shares approximate their fair value.
	Impairment Testing of Investments
	We review our investment portfolio each reporting period to determine whether there are identified events or circumstances that would indicate there is a decline in the fair value that would be considered other than temporary. For our nonpublic investments, if there are no identified events or circumstances that would have a significant adverse effect on the fair value of the investment, then the fair value is not estimated. If an investment is deemed to have experienced an other-than-temporary decline below its cost basis, we reduce the carrying amount of the investment to its quoted or estimated fair value, as applicable, and establish a new cost basis for the investment. For our AFS and cost method investments, we record the impairment to investment income (loss), net. For our equity method investments, we record the impairment to other income (expense), net. During 2013, we recorded $249 million of impairment charges to our equity method investments, which were primarily related to a regional sports cable network based in Houston, Texas.
NBCUniversal Media, LLC [Member]	'
Investments	'
	Note 6: Investments
				Successor
	December 31 (in millions)			2013		2012
	Fair Value Method		$	11	$	21
	Equity Method:
		The Weather Channel		333		471
		Hulu		187		-
		Other		332		545
				852		1,016
	Cost Method			21		229
	Total investments		$	884	$	1,266
	Equity Method
	We use the equity method to account for investments in which we have the ability to exercise significant influence over the investee's operating and financial policies or where we hold significant partnership or LLC interests. Equity method investments are recorded at cost and are adjusted to recognize (i) our proportionate share of the investee's net income or losses after the date of investment, (ii) amortization of the recorded investment that exceeds our share of the book value of the investee's net assets, (iii) additional contributions made and dividends received, and (iv) impairments resulting from other-than-temporary declines in fair value. Gains or losses on the sale of equity method investments are recorded to other income (expense), net. If an equity method investee were to issue additional securities that would change our proportionate share of the entity, we would recognize the change, if any, as a gain or loss in our consolidated statement of income.
	The Weather Channel
	In June 2013, we received a distribution from The Weather Channel Holding Corp. (“The Weather Channel”) of $152 million, of which $128 million was recorded as a return of our investment in The Weather Channel and included under the caption “return of capital from investees” in our consolidated statement of cash flows.
	Hulu
	In July 2013, we entered into an agreement to provide capital contributions totaling $247 million to Hulu, LLC (“Hulu”), which we had previously accounted for as a cost method investment. This represented an agreement to provide our first capital contribution to Hulu since Comcast acquired its interest in Hulu as part of the Joint Venture transaction, therefore we began to apply the equity method of accounting for this investment. The change in the method of accounting for this investment required us to recognize our proportionate share of Hulu's accumulated losses from the date of the Joint Venture transaction through July 2013. Prior period financial statements have not been restated as the amounts are not material for the periods presented.
	Impairment Testing of Investments
	We review our investment portfolio each reporting period to determine whether there are identified events or circumstances that would indicate there is a decline in the fair value that would be considered other than temporary. For our nonpublic investments, if there are no identified events or circumstances that would have a significant adverse effect on the fair value of the investment, then the fair value is not estimated. If an investment is deemed to have experienced an other-than-temporary decline below its cost basis, we reduce the carrying amount of the investment to its quoted or estimated fair value, as applicable, and establish a new cost basis for the investment. For our AFS and cost method investments, we record the impairment to investment income (loss), net. For our equity method investments, we record the impairment to other income (expense), net. During 2013, we recorded $249 million of impairment charges to our equity method investments, which were primarily related to a regional sports cable network based in Houston, Texas.

Property_and_Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2013
Property and Equipment	'
	Note 7: Property and Equipment
	December 31 (in millions)	Weighted-Average Original Useful Life As of December 31, 2013			2013		2012
	Cable distribution system	11	years	$	30,498	$	29,528
	Customer premise equipment	6	years		25,949		24,763
	Other equipment	5	years		6,826		5,909
	Buildings and leasehold improvements	21	years		8,057		5,468
	Land		-		1,084		989
	Property and equipment, at cost				72,414		66,657
	Less: Accumulated depreciation				42,574		39,425
	Property and equipment, net			$	29,840	$	27,232
	Property and equipment are stated at cost. We capitalize improvements that extend asset lives and expense repairs and maintenance costs as incurred. We record depreciation using the straight-line method over the asset's estimated useful life. For assets that are sold or retired, we remove the applicable cost and accumulated depreciation and, unless the gain or loss on disposition is presented separately, we recognize it as a component of depreciation expense.
	We capitalize the costs associated with the construction of and improvements to our cable transmission and distribution facilities, costs associated with acquiring and deploying new customer premise equipment, and costs associated with installation of our services in accordance with accounting guidance related to cable television companies. Costs capitalized include all direct labor and materials, as well as various indirect costs. All costs incurred in connection with subsequent disconnects and reconnects are expensed as they are incurred.
	We evaluate the recoverability of our property and equipment whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of depreciation expense.
	Acquisitions of Real Estate Properties
	Real estate acquisitions for 2013 primarily included NBCUniversal's purchase from GE of certain properties NBCUniversal occupies at 30 Rockefeller Plaza in New York City and CNBC's headquarters in Englewood Cliffs, New Jersey. The CNBC property was previously recorded as a capital lease in our consolidated balance sheet. Other acquisitions included NBCUniversal's purchase in September 2013 of a business whose primary asset is a property located at 10 Universal City Plaza, which is adjacent to Universal Studios in Hollywood, California, and Comcast's purchase in December 2013 of an 80% interest in a business whose primary asset is our corporate headquarters in Philadelphia, Pennsylvania. These purchases resulted in increases of $2.2 billion in property and equipment which are included, as applicable, within the captions “buildings and leasehold improvements” and “land” in the table above.
NBCUniversal Media, LLC [Member]	'
Property and Equipment	'
	Note 7: Property and Equipment
					Successor
	December 31 (in millions)	Weighted-Average Original Useful Life As of December 31, 2013			2013		2012
	Buildings and leasehold improvements	20	years	$	5,239	$	3,223
	Furniture, fixtures and equipment	6	years		2,383		1,961
	Construction in process		-		828		552
	Land		-		799		728
	Property and equipment, at cost				9,249		6,464
	Less: Accumulated depreciation				1,599		1,083
	Property and equipment, net			$	7,650	$	5,381
	Property and equipment are stated at cost. We capitalize improvements that extend asset lives and expense repairs and maintenance costs as incurred. We record depreciation using the straight-line method over the asset's estimated useful life. For assets that are sold or retired, we remove the applicable cost and accumulated depreciation and, unless the gain or loss on disposition is presented separately, we recognize it as a component of depreciation expense.
	We evaluate the recoverability of our property and equipment whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of depreciation expense.
	Acquisitions of Real Estate Properties
	Real estate acquisitions for 2013 primarily included our purchase from GE of certain properties we occupy at 30 Rockefeller Plaza in New York City and CNBC's headquarters in Englewood Cliffs, New Jersey. The CNBC property was previously recorded as a capital lease in our consolidated balance sheet. Other acquisitions included our purchase in September 2013 of a business whose primary asset is a property located at 10 Universal City Plaza, which is adjacent to Universal Studios in Hollywood, California. These purchases resulted in increases of $1.7 billion in property and equipment which are included, as applicable, within the captions “buildings and leasehold improvements” and “land” in the table above.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2013
Goodwill and Intangible Assets	'
	Note 8: Goodwill and Intangible Assets
	Goodwill
					NBCUniversal
	(in millions)			Cable Communications		Cable Networks		Broadcast Television		Filmed Entertainment		Theme Parks		Corporate and Other		Total
	Balance, December 31, 2011		$	12,208	$	12,744	$	772	$	1	$	1,140	$	9	$	26,874
	Acquisitions:
		MSNBC.com		-		227		-		-		-		-		227
		Other		-		79		-		-		-		-		79
	Dispositions			-1		-		-		-		-		-		-1
	Adjustments(a)			-1		-24		-11		-		-158		-		-194
	Balance, December 31, 2012			12,206		13,026		761		1		982		9		26,985
	Acquisitions			-		39		3		-		-		-		42
	Adjustments(a)			-		65		5		-		-		1		71
	Balance, December 31, 2013		$	12,206	$	13,130	$	769	$	1	$	982	$	10	$	27,098
	(a) Adjustments to goodwill in 2013 were primarily related to an immaterial correction to the allocation of purchase price associated with the NBCUniversal transaction. Adjustments to goodwill in 2012 were primarily related to the adjustments to the allocation of purchase price associated with the Universal Orlando transaction in 2011.
	We assess the recoverability of our goodwill annually, or more frequently whenever events or substantive changes in circumstances indicate that the carrying amount of a reporting unit may exceed its fair value. We test goodwill for impairment at the reporting unit level. To determine our reporting units, we evaluate the components one level below the segment level and we aggregate the components if they have similar economic characteristics. As a result of this assessment, our reporting units are the same as our five reportable segments. We evaluate the determination of our reporting units used to test for impairment periodically or whenever events or substantive changes in circumstances occur. The assessment of recoverability may first consider qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. The quantitative assessment considers if the carrying amount of a reporting unit exceeds its fair value, in which case an impairment charge is recorded to the extent the carrying amount of the reporting unit's goodwill exceeds its implied fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Intangible Assets
						2013				2012
	December 31 (in millions)		Weighted-Average Original Useful Life as of December 31, 2013			Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
	Indefinite-Lived Intangible Assets:
		Franchise rights		N/A	$	59,364			$	59,364
		Trade names		N/A		3,089				3,080
		FCC licenses		N/A		652				636
	Finite-Lived Intangible Assets:
		Customer relationships	19	years		15,037	$	-4,772		14,970	$	-3,971
		Cable franchise renewal costs and contractual operating rights	10	years		1,360		-745		1,257		-676
		Software	5	years		4,271		-2,405		3,795		-2,123
		Patents and other technology rights	9	years		361		-307		350		-283
		Other agreements and rights	20	years		1,433		-645		1,414		-609
	Total				$	85,567	$	-8,874	$	84,866	$	-7,662
	Indefinite-Lived Intangible Assets
	Indefinite-lived intangible assets consist primarily of our cable franchise rights, as well as trade names and FCC licenses. Our cable franchise rights represent the values we attributed to agreements with state and local authorities that allow access to homes and businesses in cable service areas acquired in business combinations. We do not amortize our cable franchise rights because we have determined that they meet the definition of indefinite-lived intangible assets since there are no legal, regulatory, contractual, competitive, economic or other factors which limit the period over which these rights will contribute to our cash flows. We reassess this determination periodically or whenever events or substantive changes in circumstances occur. Costs we incur in negotiating and renewing cable franchise agreements are included in other intangible assets and are generally amortized on a straight-line basis over the term of the franchise agreement.
	We assess the recoverability of our franchise rights and other indefinite-lived intangible assets annually, or more frequently whenever events or substantive changes in circumstances indicate that the assets might be impaired. Our three Cable Communications divisions represent the unit of account we use to test for impairment for our cable franchise rights. We evaluate the unit of account used to test for impairment of our cable franchise rights and other indefinite-lived intangible assets periodically or whenever events or substantive changes in circumstances occur to ensure impairment testing is performed at an appropriate level. The assessment of recoverability may first consider qualitative factors to determine whether it is more likely than not that the fair value of an indefinite-lived intangible asset is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. When performing a quantitative assessment, we estimate the fair value of our cable franchise rights and other indefinite-lived intangible assets primarily based on a discounted cash flow analysis that involves significant judgment. When analyzing the fair values indicated under the discounted cash flow models, we also consider multiples of operating income before depreciation and amortization generated by the underlying assets, current market transactions, and profitability information. If the fair value of our cable franchise rights or other indefinite-lived intangible assets were less than the carrying amount, we would recognize an impairment charge for the difference between the estimated fair value and the carrying value of the assets. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Finite-Lived Intangible Assets
	Estimated Amortization Expense of Finite-Lived Intangibles
	(in millions)
	2014	$	1,487
	2015	$	1,345
	2016	$	1,196
	2017	$	1,046
	2018	$	893
	Finite-lived intangible assets are subject to amortization and consist primarily of customer relationships acquired in business combinations, cable franchise renewal costs, contractual operating rights, intellectual property rights and software. Our finite-lived intangible assets are amortized primarily on a straight-line basis over their estimated useful life or the term of the respective agreement.
	We capitalize direct development costs associated with internal-use software, including external direct costs of material and services and payroll costs for employees devoting time to these software projects. We also capitalize costs associated with the purchase of software licenses. We include these costs in other intangible assets and amortize them on a straight-line basis over a period not to exceed five years. We expense maintenance and training costs, as well as costs incurred during the preliminary stage of a project, as they are incurred. We capitalize initial operating system software costs and amortize them over the life of the associated hardware.
	We evaluate the recoverability of our intangible assets subject to amortization whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
NBCUniversal Media, LLC [Member]	'
Goodwill and Intangible Assets	'
	Note 8: Goodwill and Intangible Assets
	Goodwill
	Successor (in millions)			Cable Networks		Broadcast Television		Filmed Entertainment		Theme Parks		Total
	Balance, December 31, 2011		$	12,744	$	772	$	1	$	1,140	$	14,657
	Acquisitions:
		MSNBC.com		227		-		-		-		227
		Other		79		-		-		-		79
	Adjustments(a)			-24		-11		-		-158		-193
	Balance, December 31, 2012			13,026		761		1		982		14,770
	Acquisitions			39		3		-		-		42
	Adjustments(a)			65		5		-		-		70
	Balance, December 31, 2013		$	13,130	$	769	$	1	$	982	$	14,882
	(a) Adjustments to goodwill in 2013 were primarily related to an immaterial correction to the allocation of purchase price associated with the Joint Venture transaction. Adjustments to goodwill in 2012 were primarily related to the adjustments to the allocation of purchase price associated with the Universal Orlando transaction in 2011.
	We assess the recoverability of our goodwill annually, or more frequently whenever events or substantive changes in circumstances indicate that the carrying amount of a reporting unit may exceed its fair value. We test goodwill for impairment at the reporting unit level. To determine our reporting units, we evaluate the components one level below the segment level and we aggregate the components if they have similar economic characteristics. As a result of this assessment, our reporting units are the same as our four reportable segments. We evaluate the determination of our reporting units used to test for impairment periodically or whenever events or substantive changes in circumstances occur. The assessment of recoverability may first consider qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. The quantitative assessment considers if the carrying amount of a reporting unit exceeds its fair value, in which case an impairment charge is recorded to the extent the carrying amount of the reporting unit's goodwill exceeds its implied fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Intangible Assets
						Successor
						2013				2012
	December 31 (in millions)		Weighted-Average Original Useful Life as of December 31, 2013			Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
	Finite-Lived Intangible Assets:
		Customer relationships	19 years		$	13,086	$	-2,982	$	13,026	$	-2,328
		Software	5 years			522		-240		409		-164
		Other	21 years			1,511		-781		1,507		-746
	Indefinite-Lived Intangible Assets:
		Trade names				3,089				3,080
		FCC licenses				652				636
	Total				$	18,860	$	-4,003	$	18,658	$	-3,238
	Indefinite-Lived Intangible Assets
	Indefinite-lived intangible assets consist of trade names and FCC licenses. We assess the recoverability of our indefinite-lived intangible assets annually, or more frequently whenever events or substantive changes in circumstances indicate that the assets might be impaired. We evaluate the unit of account used to test for impairment of our indefinite-lived intangible assets periodically or whenever events or substantive changes in circumstances occur to ensure impairment testing is performed at an appropriate level. The assessment of recoverability may first consider qualitative factors to determine whether it is more likely than not that the fair value of an indefinite-lived intangible asset is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. When performing a quantitative assessment, we estimate the fair value of our indefinite-lived intangible assets primarily based on a discounted cash flow analysis that involves significant judgment. When analyzing the fair values indicated under the discounted cash flow models, we also consider multiples of operating income before depreciation and amortization generated by the underlying assets, current market transactions, and profitability information. If the fair value of our indefinite-lived intangible assets were less than the carrying amount, we would recognize an impairment charge for the difference between the estimated fair value and the carrying value of the assets. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Finite-Lived Intangible Assets
	Estimated Amortization Expense of Finite-Lived Intangibles
	(in millions)
	2014	$	771
	2015	$	762
	2016	$	739
	2017	$	740
	2018	$	734
	Finite-lived intangible assets are subject to amortization and consist primarily of customer relationships acquired in business combinations, intellectual property rights and software. Our finite-lived intangible assets are amortized primarily on a straight-line basis over their estimated useful life or the term of the respective agreement.
	We capitalize direct development costs associated with internal-use software, including external direct costs of material and services and payroll costs for employees devoting time to these software projects. We also capitalize costs associated with the purchase of software licenses. We include these costs in intangible assets and amortize them on a straight-line basis over a period not to exceed five years. We expense maintenance and training costs, as well as costs incurred during the preliminary stage of a project, as they are incurred. We capitalize initial operating system software costs and amortize them over the life of the associated hardware.
	We evaluate the recoverability of our intangible assets subject to amortization whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.

LongTerm_Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2013
Long-Term Debt	'
	Note 9: Long-Term Debt
	Long-Term Debt Outstanding
	December 31 (in millions)	Weighted-Average Interest Rate as of December 31, 2013			2013		2012
	Commercial paper	0.295	%	$	1,350	$	-
	Revolving bank credit facilities	1.166	%		1,250		-
	Senior notes with maturities of 5 years or less	4.718	%		15,080		12,991
	Senior notes with maturities between 6 and 10 years	4.558	%		11,533		10,334
	Senior notes with maturities greater than 10 years(a)	5.971	%		18,010		16,801
	Other, including capital lease obligations	—			624		332
	Total debt	4.8	%(b)		47,847		40,458
	Less: Current portion				3,280		2,376
	Long-term debt			$	44,567	$	38,082
	(a) Both the December 31, 2013 and 2012 amounts include £625 million of 5.50% notes due 2029 translated at $1 billion, using the exchange rates as of these dates.
	(b) Includes the effects of our derivative financial instruments.
	As of December 31, 2013 and 2012, our debt had an estimated fair value of $51.8 billion and $47.7 billion, respectively. The estimated fair value of our publicly traded debt is based on quoted market values for the debt. To estimate the fair value of debt for which there are no quoted market prices, we use interest rates available to us for debt with similar terms and remaining maturities. See Note 21 for additional information on our subsidiary guarantee structures.
	Debt Maturities
	(in millions)	Weighted-Average Interest Rate
	2014	2.343	%		$	3,280
	2015	5.899	%		$	3,420
	2016	4.265	%		$	3,501
	2017	6.977	%		$	2,557
	2018	4.51	%		$	5,394
	Thereafter	5.451	%		$	29,695
	2013 Debt Borrowings
	Year ended December 31, 2013 (in millions)
	Comcast 4.250% senior notes due 2033	$	1,700
	Comcast 2.850% senior notes due 2023		750
	Comcast 4.500% senior notes due 2043		500
	Total	$	2,950
	2013 Debt Repayments and Redemptions
	Year ended December 31, 2013 (in millions)
	Comcast 8.375% senior notes due 2013	$	1,714
	Comcast 7.125% senior notes due 2013		383
	Comcast 7.875% senior notes due 2013		238
	Other		109
	Total	$	2,444
	Redemption Transaction
	The Redemption Transaction resulted in the consolidation of an additional $4 billion aggregate principal amount of senior notes issued by NBCUniversal Enterprise and $1.25 billion of borrowings under the NBCUniversal Enterprise credit facility. The total consideration for the Redemption Transaction also included $750 million of cash funded through our commercial paper program.
	The NBCUniversal Enterprise senior notes are comprised of $1.1 billion aggregate principal amount of 1.662% senior notes due 2018, $1.5 billion aggregate principal amount of 1.974% senior notes due 2019, $700 million aggregate principal amount of floating rate senior notes due 2016 and $700 million aggregate principal amount of floating rate senior notes due 2018. The floating rate senior notes due 2016 and 2018 will accrue interest for each quarterly interest period at a rate equal to three-month London Interbank Offered Rate (“LIBOR”) plus 0.537% and 0.685%, respectively.
	On March 19, 2013, NBCUniversal Enterprise amended and restated the existing credit agreement of NBCUniversal to, among other things, substitute NBCUniversal Enterprise for NBCUniversal as the sole borrower, reduce the borrowing capacity of the facility from $1.5 billion to $1.35 billion, extend the term of the facility to March 2018 and revise the interest rate on borrowings. The interest rate on the credit facility consists of a base rate plus a borrowing margin that is determined based on our credit rating. Following the amendments to this credit agreement, NBCUniversal's commercial paper program was terminated. As of December 31, 2013, $1.25 billion was outstanding under this credit facility.
	Debt Instruments
	Revolving Credit Facilities
	As of December 31, 2013, Comcast Corporation and Comcast Cable Communications, LLC had a $6.25 billion revolving credit facility due June 2017 with a syndicate of banks. The interest rate on this facility consists of a base rate plus a borrowing margin that is determined based on our credit rating. As of December 31, 2013, the borrowing margin for LIBOR-based borrowings was 1.00%. This revolving credit facility requires that we maintain certain financial ratios based on our debt and our operating income before depreciation and amortization, as defined in the credit facility. We were in compliance with all financial covenants for all periods presented.
	As of December 31, 2013, amounts available under our consolidated credit facilities, net of amounts outstanding under our commercial paper program and outstanding letters of credit, totaled $4.7 billion, which included $100 million available under NBCUniversal Enterprise's credit facility.
	Commercial Paper Program
	Our commercial paper program provides a lower cost source of borrowing to fund our short-term working capital requirements and is supported by our $6.25 billion revolving credit facility due June 2017. In September 2013, we increased the borrowing capacity of our commercial paper program from $2.25 billion to $6.25 billion.
	Letters of Credit
	As of December 31, 2013, we and certain of our subsidiaries had unused irrevocable standby letters of credit totaling $515 million to cover potential fundings under various agreements.
NBCUniversal Media, LLC [Member]	'
Long-Term Debt	'
	Note 9: Long-Term Debt
	Long-Term Debt Outstanding
		Weighted-Average Interest Rate as of December 31, 2013		Successor
	December 31 (in millions)				2013			2012
	Senior notes with maturities of 5 years or less	2.884	%		2,917		2,933
	Senior notes with maturities between 6 and 10 years	4.388	%		4,996		3,999
	Senior notes with maturities greater than 10 years	5.614	%		3,205		4,203
	Other, including capital lease obligations	—			47		106
	Total debt	4.22	%(a)		11,165		11,241
	Less: Current portion				906		10
	Long-term debt			$	10,259		11,231
	(a) Includes the effects of our derivative financial instruments.
	As of December 31, 2013 and 2012, our debt had an estimated fair value of $11.7 billion and $12.6 billion, respectively. The estimated fair value of our publicly traded debt is based on quoted market values for the debt. To estimate the fair value of debt for which there are no quoted market prices, we use interest rates available to us for debt with similar terms and remaining maturities.
	Debt Maturities
	(in millions)	Weighted-Average Interest Rate
	2014	2.121	%		$	906
	2015	3.597	%		$	1,032
	2016	2.876	%		$	1,008
	2017	6.287	%		$	2
	2018	6.299	%		$	2
	Thereafter	4.871	%		$	8,215
	Debt Instruments
	Revolving Credit Facility
	In connection with the Redemption Transaction, on March 19, 2013, NBCUniversal Enterprise amended and restated our existing credit agreement to, among other things, substitute NBCUniversal Enterprise for us as the sole borrower to the revolving credit facility. As a result, we no longer have a revolving credit facility with third-party banks. Following the amendments to our credit agreement, our commercial paper program was terminated and we entered into a revolving credit agreement with Comcast. See Note 4 for additional information on the revolving credit agreement with Comcast.
	Cross-Guarantee Structure
	On March 27, 2013, we, Comcast and four of Comcast's wholly owned cable holding company subsidiaries (the “cable guarantors”) entered into a series of agreements and supplemental indentures to include us as a part of Comcast's existing cross-guarantee structure. As members of the cross-guarantee structure, Comcast and the cable guarantors fully and unconditionally guarantee our public debt securities, and we fully and unconditionally guarantee all of Comcast's and the cable guarantors' public debt securities. As of December 31, 2013, we guaranteed $31 billion of outstanding debt securities of Comcast and the cable guarantors. We also fully and unconditionally guarantee the $6.25 billion Comcast revolving credit facility due 2017, of which no amounts were outstanding as of December 31, 2013.
	We do not, however, guarantee the obligations of NBCUniversal Enterprise with respect to its $4 billion aggregate principal amount of senior notes, $1.35 billion revolving credit facility or $725 million liquidation preference of Series A cumulative preferred stock.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2013
Fair Value Measurements	'
	Note 10: Fair Value Measurements
	The accounting guidance related to financial assets and financial liabilities (“financial instruments”) establishes a hierarchy that prioritizes fair value measurements based on the types of inputs used for the various valuation techniques (market approach, income approach and cost approach). The levels of the hierarchy are described below.
	Level 1: Consists of financial instruments whose values are based on quoted market prices for identical financial instruments in an active market.
	Level 2: Consists of financial instruments that are valued using models or other valuation methodologies. These models use inputs that are observable either directly or indirectly. Level 2 inputs include (i) quoted prices for similar assets or liabilities in active markets, (ii) quoted prices for identical or similar assets or liabilities in markets that are not active, (iii) pricing models whose inputs are observable for substantially the full term of the financial instrument and (iv) pricing models whose inputs are derived primarily from or corroborated by observable market data through correlation or other means for substantially the full term of the financial instrument.
	Level 3: Consists of financial instruments whose values are determined using pricing models that use significant inputs that are primarily unobservable, discounted cash flow methodologies or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation.
	Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of financial instruments and their classification within the fair value hierarchy. Financial instruments are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. There have been no changes in the classification of any financial instruments within the fair value hierarchy in the periods presented. Our financial instruments that are accounted for at fair value on a recurring basis are presented in the table below.
	Recurring Fair Value Measures
			Fair Value as of December 31, 2013								Fair Value as of December 31, 2012
	(in millions)		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	Assets
	Trading securities	$	3,956	$	-	$	-	$	3,956	$	4,027	$	-	$	-	$	4,027
	Available-for-sale securities		260		118		11		389		367		76		21		464
	Interest rate swap agreements		-		110		-		110		-		210		-		210
	Other		-		80		1		81		-		36		2		38
	Total	$	4,216	$	308	$	12	$	4,536	$	4,394	$	322	$	23	$	4,739
	Liabilities
	Derivative component of prepaid forward sale agreements and indexed debt instruments	$	-	$	2,816	$	-	$	2,816	$	-	$	2,305	$	-	$	2,305
	Contractual obligations				-		747		747		-		-		1,055		1,055
	Contingent consideration		-		-		684		684		-		-		587		587
	Other		-		16		-		16		-		14		-		14
	Total	$	-	$	2,832	$	1,431	$	4,263	$	-	$	2,319	$	1,642	$	3,961
	Contractual Obligations and Contingent Consideration
	The fair values of the contractual obligations and contingent consideration in the table above are primarily based on certain expected future discounted cash flows, the determination of which involves the use of significant unobservable inputs. The most significant unobservable inputs we use are our estimates of the future revenue we expect to generate from certain NBCUniversal entities, which are related to our contractual obligations, and future net tax benefits that will affect payments to GE, which are related to contingent consideration. The discount rates used in the measurements of fair value were between 5% and 13% and are based on the underlying risk associated with our estimate of future revenue, as well as the terms of the respective contracts, and the uncertainty in the timing of our payments to GE. The fair value adjustments to contractual obligations and contingent consideration are sensitive to the assumptions related to future revenue and tax benefits, respectively, as well as to current interest rates, and therefore, the adjustments are recorded to other income (expense), net in our consolidated statement of income.
	Changes in Contractual Obligations and Contingent Consideration
	(in millions)		Contractual Obligations		Contingent Consideration
	Balance, December 31, 2012	$	1,055	$	587
	Fair value adjustments		158		106
	Payments		-83		-214
	Redemption Transaction (see Note 4 for additional information)		-		205
	Liberty Media transaction (see Note 6 for additional information)		-383		-
	Balance, December 31, 2013	$	747	$	684
	Nonrecurring Fair Value Measures
	We have assets and liabilities that are required to be recorded at fair value on a nonrecurring basis when certain circumstances occur. In the case of film or stage play production costs, upon the occurrence of an event or change in circumstance that may indicate that the fair value of a production is less than its unamortized costs, we determine the fair value of the production and record an adjustment for the amount by which the unamortized capitalized costs exceed the production's fair value. The estimate of fair value of a production is determined using Level 3 inputs, primarily an analysis of future expected cash flows. Adjustments to capitalized film and stage play production costs of $167 million and $161 million were recorded in 2013 and 2012, respectively.
NBCUniversal Media, LLC [Member]	'
Fair Value Measurements	'
	Note 10: Fair Value Measurements
	The accounting guidance related to financial assets and financial liabilities (“financial instruments”) establishes a hierarchy that prioritizes fair value measurements based on the types of inputs used for the various valuation techniques (market approach, income approach and cost approach). Our assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of financial instruments and their classification within the fair value hierarchy.
	Our financial instruments that are accounted for at fair value on a recurring basis were not material for all periods presented, except for liabilities associated with our contractual obligations. The fair values of the contractual obligations in the table below are primarily based on certain expected future discounted cash flows, the determination of which involves the use of significant unobservable inputs. As the inputs used are not quoted market prices or observable inputs, we classify these contractual obligations as Level 3 financial instruments.
	The most significant unobservable inputs we use are our estimates of the future revenue we expect to generate from certain of our entities. The discount rates used in the measurements of fair value as of December 31, 2013 were between 12% and 13% and are based on the underlying risk associated with our estimate of future revenue, as well as the terms of the respective contracts. The fair value adjustments to contractual obligations are sensitive to the assumptions related to future revenue, as well as to current interest rates, and therefore, the adjustments are recorded to other income (expense), net in our consolidated statement of income.
	In October 2013, Comcast closed its transaction with Liberty Media Corporation (“Liberty Media”), which included, among other things, the delivery of Liberty Media shares held by Comcast in exchange for Liberty Media's interests in one of our contractual obligations. The liability associated with this contractual obligation is now considered a related party transaction and as a result we no longer remeasure this liability to its fair value on a recurring basis.
	Changes in Contractual Obligations
	Successor (in millions)
	Balance, December 31, 2012	$	1,055
	Fair value adjustments		158
	Payments		-83
	Liberty Media transaction		-383
	Balance, December 31, 2013	$	747
	Nonrecurring Fair Value Measures
	We have assets and liabilities that are required to be recorded at fair value on a nonrecurring basis when certain circumstances occur. In the case of film or stage play production costs, upon the occurrence of an event or change in circumstance that may indicate that the fair value of a production is less than its unamortized costs, we determine the fair value of the production and record an adjustment for the amount by which the unamortized capitalized costs exceed the production's fair value. The estimate of fair value of a production is determined using Level 3 inputs, primarily an analysis of future expected cash flows. Adjustments to capitalized film and stage play production costs of $167 million and $161 million were recorded in 2013 and 2012, respectively.

Noncontrolling_Interests

Noncontrolling Interests	12 Months Ended
	Dec. 31, 2013
Noncontrolling Interests	'
	Note 11: Noncontrolling Interests
	Certain of the subsidiaries that we consolidate are not wholly owned. Some of the agreements with the minority partners of these subsidiaries contain redemption features whereby interests held by the minority partners are redeemable either (i) at the option of the holder or (ii) upon the occurrence of an event that is not solely within our control. If interests were to be redeemed under these agreements, we would generally be required to purchase the interest at fair value on the date of redemption. These interests are presented on the balance sheet outside of equity under the caption “redeemable noncontrolling interests and redeemable subsidiary preferred stock.” Noncontrolling interests that do not contain such redemption features are presented in equity.
	We acquired GE's remaining 49% common equity interest in NBCUniversal Holdings, which had previously been presented as a redeemable noncontrolling interest in our consolidated balance sheet. See Note 4 for additional information on the Redemption Transaction. The difference between the consideration transferred and the recorded value of GE's 49% redeemable noncontrolling common equity interest, as well as the related tax impacts, were recorded to additional paid-in capital. The table below includes the impact of the Redemption Transaction on our changes in equity.
	Changes in Equity
	Year ended December 31 (in millions)			2013
	Net income attributable to Comcast Corporation		$	6,816
	Transfers from (to) noncontrolling interests:
		Decrease in Comcast Corporation additional paid-in capital resulting from the
		purchase of GE’s redeemable noncontrolling common equity interest		-1,651
		Other		-26
	Changes in equity resulting from net income attributable to Comcast Corporation and
		transfers from (to) noncontrolling interests	$	5,139

Pension_Plans_and_Postretireme

Pension Plans and Postretirement Benefits	12 Months Ended
	Dec. 31, 2013
Postretirement, Pension and Other Employee Benefit Plans	'
	Note 12: Postretirement, Pension and Other Employee Benefit Plans
	The table below provides condensed information on our postretirement and pension benefit plans.
				2013					2012						2011
	Year ended December 31 (in millions)			Postretirement Benefits		Pension Benefits			Postretirement Benefits			Pension Benefits			Postretirement Benefits			Pension Benefits
	Benefit obligation		$	633		$	498		$	703		$	805		$	618		$	638
	Fair value of plan assets(a)			-			220			-			403			-			176
	Plan funded status and recorded
		benefit obligation		-633			-278			-703			-402			-618			-462
	Portion of benefit obligation not
		yet recognized in benefits expense		-110			-3			17			151			-17			137
	Benefits expense(b)			65			12			60			163			47			117
	Discount rate			5.00-5.25	%	4.50-5.25		%		4.25	%	3.25-4.25		%		4.75	%	4.75-5.25		%
	Expected return on plan assets			N/A			5	%		N/A			5	%		N/A			6.5	%
	(a) The fair value of the plan assets are primarily based on Level 1 inputs using quoted market prices for identical financial instruments in an active market.
	(b) We did not recognize service cost in 2013 as our pension plans were frozen. The 2012 and 2011 amounts included service costs related to our pension benefits of $139 million and $99 million, respectively.
	Postretirement Benefit Plans
	We and NBCUniversal sponsor various benefit plans that provide postretirement benefits to eligible employees based on years of service. The Comcast Postretirement Healthcare Stipend Program (the “stipend plan”) provides an annual stipend for reimbursement of healthcare costs to each eligible employee based on years of service. Under the stipend plans, we are not exposed to the increasing costs of healthcare because the benefits are fixed at a predetermined amount.
	NBCUniversal's postretirement medical and life insurance plans provide continuous coverage to employees eligible to receive such benefits. A small number of eligible employees also participate in legacy plans of acquired companies.
	All of our postretirement benefit plans are unfunded and substantially all of our postretirement benefit obligations are recorded to noncurrent liabilities. The expense we recognize related to our postretirement benefit plans is determined using certain assumptions, including the discount rate.
	Pension Plans
	NBCUniversal
	NBCUniversal sponsors various domestic qualified and nonqualified defined benefit plans for which future benefits were frozen effective December 31, 2012. We ceased to recognize service costs associated with these defined benefit plans following the date on which future benefits were frozen. The expense we recognize related to our defined benefit plans is determined using certain assumptions, including the discount rate and the expected long-term rate of return on plan assets. We recognize the funded or unfunded status of our defined benefit plans as an asset or liability in our consolidated balance sheet and recognize changes in the funded status in the year in which the changes occur through accumulated other comprehensive income (loss). In the event of a defined benefit plan termination, we expect to fully fund and settle the plan within 180 days of approval by the Internal Revenue Service (“IRS”) and the Pension Benefit Guaranty Corporation (“PBGC”). In addition to the defined benefit plans it sponsors, NBCUniversal is also obligated to reimburse GE for future benefit payments to those participants who were vested in the supplemental pension plan sponsored by GE at the time of the close of the NBCUniversal transaction.
	In October 2013, NBCUniversal provided notice to the plan participants of its qualified pension plan of its intent to terminate its plan effective December 31, 2013. The NBCUniversal qualified pension plan was unfunded by $8 million as of December 31, 2013, and NBCUniversal expects to seek approval for this termination from the IRS and PBGC in 2014.
	Other
	In August 2013, we settled all of our obligations related to the termination in February 2012 of the qualified pension plan that provided benefits to former employees of a company we acquired as part of the AT&T Broadband transaction in 2002. In connection with this final settlement, we fully funded the plan with additional contributions of $55 million and recorded an expense of $74 million in other operating and administrative expenses, which was previously recorded in accumulated other comprehensive income (loss).
	Other Employee Benefits
	Deferred Compensation Plans
	We maintain unfunded, nonqualified deferred compensation plans for certain members of management and nonemployee directors (each, a “participant”). The amount of compensation deferred by each participant is based on participant elections. Participant accounts, except for those in the NBCUniversal plan, are credited with income primarily based on a fixed annual rate. Participants in the NBCUniversal plan designate one or more valuation funds, independently established funds or indices that are used to determine the amount of earnings to be credited or debited to the participant's account. Participants are eligible to receive distributions of the amounts credited to their account based on elected deferral periods that are consistent with the plans and applicable tax law.
	The table below presents the benefit obligation and interest expense for our deferred compensation plans.
	Year ended December 31 (in millions)		2013		2012		2011
	Benefit obligation	$	1,434	$	1,247	$	1,059
	Interest expense	$	128	$	107	$	99
	We have purchased life insurance policies to recover a portion of the future payments related to our deferred compensation plans. As of December 31, 2013 and 2012, the cash surrender value of these policies, which is recorded to other noncurrent assets, was $565 million and $478 million, respectively.
	Retirement Investment Plans
	We sponsor several 401(k) defined contribution retirement plans that allow eligible employees to contribute a portion of their compensation through payroll deductions in accordance with specified plan guidelines. We make contributions to the plans that include matching a percentage of the employees' contributions up to certain limits. In 2013, 2012 and 2011, expenses related to these plans totaled $324 million, $246 million and $226 million, respectively.
	Split-Dollar Life Insurance Agreements
	We have collateral assignment split-dollar life insurance agreements with select key current and former employees that require us to incur certain insurance-related costs. Under some of these agreements, our obligation to provide benefits to the employees extends beyond retirement.
	The table below presents the benefit obligation and expenses related to our split-dollar life insurance agreements.
	Year ended December 31 (in millions)		2013		2012		2011
	Benefit obligation	$	212	$	202	$	169
	Other operating and administrative expenses	$	50	$	58	$	27
	Multiemployer Benefit Plans
	We also participate in various multiemployer pension and other postretirement benefit plans through the activities of NBCUniversal that cover some of our employees and temporary employees who are represented by labor unions. We make periodic contributions to these plans in accordance with the terms of applicable collective bargaining agreements and laws but do not sponsor or administer these plans. We do not participate in any multiemployer benefit plans for which we consider our contributions to be individually significant, and the largest plans in which we participate are funded at a level of 80% or greater. In 2013, 2012 and 2011, the total contributions we made to multiemployer pension and other postretirement benefit plans were $66 million, $53 million and $42 million, respectively.
	If we cease to be obligated to make contributions or otherwise withdraw from participation in any of these plans, applicable law requires us to fund our allocable share of the unfunded vested benefits, which is known as a withdrawal liability. In addition, actions taken by other participating employers may lead to adverse changes in the financial condition of one of these plans, which could result in an increase in our withdrawal liability.
	Severance Benefits
	We provide severance benefits to certain former employees. A liability is recorded for benefits provided when payment is probable, the amount is reasonably estimable, and the obligation relates to rights that have vested or accumulated. During 2013, 2012 and 2011, we recorded $160 million, $155 million and $128 million, respectively, of severance costs.
NBCUniversal Media, LLC [Member]	'
Postretirement, Pension and Other Employee Benefit Plans	'
	Note 11: Postretirement, Pension and Other Employee Benefit Plans
	The table below provides condensed information on our postretirement and pension benefit plans.
			Successor
			Year Ended December 31,						Year Ended December 31,						For the Period January 29, 2011 to December 31,
			2013						2012						2011
	(in millions)		Postretirement Benefits			Pension Benefits			Postretirement Benefits			Pension Benefits			Postretirement Benefits			Pension Benefits
	Benefit obligation		$	158		$	498		$	177		$	546		$	161		$	427
	Fair value of plan assets(a)			-			220			-			217			-			-
	Plan funded status and recorded
		benefit obligation		-158			-278			-177			-329			-161			-427
	Portion of benefit obligation not yet
		recognized in benefit expense		-44			-3			-11			53			-13			71
	Benefits expense(b)			14			12			15			142			14			111
	Discount rate			5.25	%		4.5-5.25	%		4.25	%		3.75-4.25	%		4.75	%		4.75-5.25	%
	Expected return on plan assets			N/A			5	%		N/A			5	%		N/A			N/A
	(a) The fair value of the plan assets are primarily based on Level 1 inputs using quoted market prices for identical financial instruments in an active market.
	(b) We did not recognize service cost in 2013 as our pension plans were frozen. The 2012 and 2011 amounts included service costs related to our pension benefits of $134 million and $99 million, respectively.
	Postretirement Benefit Plans
	We have postretirement medical and life insurance plans that provide continuous coverage to employees eligible to receive such benefits and give credit for length of service provided before the close of the Joint Venture transaction.
	Substantially all of the employees that joined NBCUniversal from the Comcast Content Business at the close of the Joint Venture transaction participate in a postretirement healthcare stipend program (the “stipend plan”). The stipend plan provides an annual stipend for reimbursement of healthcare costs to each eligible employee based on years of service. Under the stipend plan, we are not exposed to the increasing costs of healthcare because the benefits are fixed at a predetermined amount.
	All of our postretirement benefit plans are unfunded and substantially all of our postretirement benefit obligations are recorded to noncurrent liabilities. The expense we recognize related to our postretirement benefit plans is determined using certain assumptions, including the discount rate.
	Pension Plans
	We sponsor various domestic qualified and nonqualified defined benefit plans for which future benefits were frozen effective December 31, 2012. We ceased to recognize service costs associated with these defined benefit plans following the date on which future benefits were frozen. The expense we recognize related to our defined benefit plans is determined using certain assumptions, including the discount rate and the expected long-term rate of return on plan assets. We recognize the funded or unfunded status of our defined benefit plans as an asset or liability in our consolidated balance sheet and recognize changes in the funded status in the year in which the changes occur through accumulated other comprehensive income (loss). In the event of a defined benefit plan termination, we expect to fully fund and settle the plan within 180 days of approval by the Internal Revenue Service (“IRS”) and the Pension Benefit Guaranty Corporation (“PBGC”). In addition to the defined benefit plans we sponsor, we are also obligated to reimburse GE for future benefit payments to those participants who were vested in the supplemental pension plan sponsored by GE at the time of the close of the Joint Venture transaction.
	In October 2013, we provided notice to the plan participants of our qualified pension plan of our intent to terminate our plan effective December 31, 2013. Our qualified pension plan was unfunded by $8 million as of December 31, 2013, and we will seek approval for this termination from the IRS and PBGC in 2014.
	Our consolidated balance sheet also includes the assets and liabilities of certain legacy pension plans, as well as the assets and liabilities for pension plans of certain foreign subsidiaries. As of December 31, 2013 and 2012, the benefit obligations associated with these plans exceeded the value of their plan assets by $43 million and $50 million, respectively.
	Other Employee Benefits
	Deferred Compensation Plans
	We maintain unfunded, nonqualified deferred compensation plans for certain members of management and nonemployee directors (each, a “participant”). The amount of compensation deferred by each participant is based on participant elections. Participants in the plan designate one or more valuation funds, independently established funds or indices that are used to determine the amount of earnings to be credited or debited to the participant's account.
	Additionally, certain of our employees participate in Comcast's unfunded, nonqualified deferred compensation plan. The amount of compensation deferred by each participant is based on participant elections. Participant accounts are credited with income primarily based on a fixed annual rate.
	In the case of both deferred compensation plans, participants are eligible to receive distributions of the amounts credited to their account based on elected deferral periods that are consistent with the plans and applicable tax law.
	The table below presents the benefit obligation and interest expense for our deferred compensation plans.
			Successor
			Year Ended December 31,		Year Ended December 31,		For the Period January 29, 2011 to December 31,
	(in millions)		2013		2012		2011
	Benefit obligation	$	250	$	163	$	114
	Interest expense	$	18	$	11	$	10
	Retirement Investment Plans
	We sponsor several 401(k) defined contribution retirement plans that allow eligible employees to contribute a portion of their compensation through payroll deductions in accordance with specified plan guidelines. We make contributions to the plans that include matching a percentage of the employees' contributions up to certain limits. In 2013, 2012 and for the period January 29, 2011 to December 31, 2011, expenses related to these plans totaled $152 million, $85 million and $70 million, respectively.
	Multiemployer Benefit Plans
	We also participate in various multiemployer pension and other postretirement benefit plans that cover some of our employees and temporary employees who are represented by labor unions. We make periodic contributions to these plans in accordance with the terms of applicable collective bargaining agreements and laws but do not sponsor or administer these plans. We do not participate in any multiemployer benefit plans for which we consider our contributions to be individually significant, and the largest plans in which we participate are funded at a level of 80% or greater. In 2013, 2012 and for the period January 29, 2011 to December 31, 2011, the total contributions we made to multiemployer pension and other postretirement benefit plans were $66 million, $53 million and $42 million, respectively.
	If we cease to be obligated to make contributions or otherwise withdraw from participation in any of these plans, applicable law requires us to fund our allocable share of the unfunded vested benefits, which is known as a withdrawal liability. In addition, actions taken by other participating employers may lead to adverse changes in the financial condition of one of these plans, which could result in an increase in our withdrawal liability.
	Severance Benefits
	We provide severance benefits to certain former employees. A liability is recorded for benefits provided when payment is probable, the amount is reasonably estimable, and the obligation relates to rights that have vested or accumulated. During 2013, 2012 and for the period January 29, 2011 to December 31, 2011, we recorded $116 million, $90 million and $89 million, respectively, of severance costs.

Equity

Equity	12 Months Ended
	Dec. 31, 2013
Equity	'
	Note 13: Equity
	Common Stock
	In the aggregate, holders of our Class A common stock have 66 2/3% of the voting power of our common stock and holders of our Class B common stock have 331/3% of the voting power of our common stock. Our Class A Special common stock is generally nonvoting. Each share of our Class B common stock is entitled to 15 votes. The number of votes held by each share of our Class A common stock depends on the number of shares of Class A and Class B common stock outstanding at any given time. The 331/3% aggregate voting power of our Class B common stock cannot be diluted by additional issuances of any other class of common stock. Our Class B common stock is convertible, share for share, into Class A or Class A Special common stock, subject to certain restrictions.
	Common Stock Outstanding
	(in millions)	A	A Special	B
	Balance, January 1, 2011	2,072	695	9
	Stock compensation plans	20	1	-
	Repurchases and retirements of common stock	-	-95	-
	Employee stock purchase plans	3	-	-
	Balance, December 31, 2011	2,095	601	9
	Stock compensation plans	24	3	-
	Repurchases and retirements of common stock	-	-96	-
	Employee stock purchase plans	3	-	-
	Balance, December 31, 2012	2,122	508	9
	Stock compensation plans	14	-	-
	Repurchases and retirements of common stock	-	-49	-
	Employee stock purchase plans	2	-	-
	Balance, December 31, 2013	2,138	459	9
	Share Repurchases
	As of December 31, 2013, we had $1.5 billion of availability remaining under the $6.5 billion share repurchase authorization approved by our Board of Directors in 2012.
	In January 2014, our Board of Directors increased our share repurchase program authorization to $7.5 billion, which does not have an expiration date. Under this authorization, we may repurchase shares in the open market or in private transactions.
	Share Repurchases
	Year ended December 31 (in millions)		2013		2012		2011
	Cash consideration	$	2,000	$	3,000	$	2,141
	Shares repurchased		49		96		95
	Accumulated Other Comprehensive Income (Loss)
	December 31 (in millions)			2013		2012
	Unrealized gains (losses) on marketable securities		$	67	$	182
	Deferred gains (losses) on cash flow hedges			-45		-67
	Unrecognized gains (losses) on employee benefit obligations			71		-95
	Cumulative translation adjustments			-37		-5
	Accumulated other comprehensive income (loss), net of deferred taxes		$	56	$	15
NBCUniversal Media, LLC [Member]	'
Equity	'
	Note 12: Equity
	NBCUniversal Holdings has caused us and will continue to cause us to make distributions or loans to NBCUniversal Holdings to meet its cash requirements. These requirements include an obligation to make distributions on a quarterly basis to enable Comcast to meet its obligations to pay taxes on taxable income generated by our businesses and quarterly payments from NBCUniversal Holdings to NBCUniversal Enterprise on the liquidation preference of its preferred units. During 2013, 2012 and the period January 29, 2011 through December 31, 2011, we made distributions to NBCUniversal Holdings of $1.4 billion, $964 million and $244 million, respectively. In addition, we also made a distribution of $3.2 billion to NBCUniversal Holdings to fund a portion of the Redemption Transaction. This distribution is presented separately on our consolidated statement of cash flows.
	In the Predecessor period ended January 28, 2011, we distributed $7.4 billion to GE prior to the close of the Joint Venture transaction.
	Accumulated Other Comprehensive Income (Loss)
			Successor
	December 31 (in millions)		2013		2012
	Deferred gains (losses) on cash flow hedges		$	-5	$	-
	Unrecognized gains (losses) on employee benefit obligations			45		-50
	Cumulative translation adjustments			-56		-15
	Accumulated other comprehensive income (loss), net of deferred taxes		$	-16	$	-65

ShareBased_Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2013
Share-Based Compensation	'
	Note 14: Share-Based Compensation
	The tables below provide condensed information on our share-based compensation.
	Recognized Share-Based Compensation Expense
	Year ended December 31 (in millions)		2013		2012		2011
	Stock options	$	139	$	131	$	116
	Restricted share units		175		154		149
	Employee stock purchase plans		20		16		13
	Total	$	334	$	301	$	278
	As of December 31, 2013, we had unrecognized pretax compensation expense of $318 million related to nonvested stock options and unrecognized pretax compensation expense of $380 million related to nonvested RSUs that will be recognized over a weighted-average period of approximately 1.9 years and 1.7 years, respectively.
	2013 Stock Options and Restricted Share Units
	As of December 31, 2013, unless otherwise stated (in millions, except per share data)			Stock Options		RSUs
	Awards granted during 2013			18		7
	Weighted-average exercise price		$	41.22
	Weighted-average fair value at grant date				$	38.28
	Stock options outstanding and nonvested RSUs(a)			104		26
	Weighted-average exercise price of stock options outstanding		$	25.49
	Weighted-average fair value at grant date of nonvested RSUs				$	25.38
	(a) As of December 31, 2013, 102 million of stock options outstanding were net settled stock options. Net settled stock options, as opposed to stock options exercised with a cash payment, result in fewer shares being issued and no cash proceeds being received by us when the options are exercised.
	Our share-based compensation primarily consists of awards of stock options and RSUs to certain employees and directors as part of our approach to long-term incentive compensation. Awards generally vest over a period of 5 years and in the case of stock options, have a 10 year term. Additionally, through our employee stock purchase plans, employees are able to purchase shares of Comcast Class A common stock at a discount through payroll deductions.
	The cost associated with our share-based compensation is based on an award's estimated fair value at the date of grant and is recognized over the period in which any related services are provided. We use the Black-Scholes option pricing model to estimate the fair value of stock option awards. RSUs are valued based on the closing price of our Class A common stock on the date of grant and are discounted for the lack of dividends, if any, during the vesting period. The table below presents the weighted-average fair value on the date of grant of RSUs and Class A common stock options awarded under our various plans and the related weighted-average valuation assumptions.
	Year Ended December 31			2013			2012			2011
	RSUs fair value		$	38.28		$	27.8		$	22.78
	Stock options fair value		$	8.8		$	7.38		$	6.96
	Stock Option Valuation Assumptions:
		Dividend yield		1.9	%		2.2	%		1.8	%
		Expected volatility		25	%		29	%		28.1	%
		Risk-free interest rate		1.3	%		1.7	%		2.8	%
		Expected option life (in years)		7			7			7
NBCUniversal Media, LLC [Member]	'
Share-Based Compensation	'
	Note 13: Share-Based Compensation
	The tables below provide condensed information on our share-based compensation.
	Recognized Share-Based Compensation Expense
		Successor
	(in millions)	Year Ended December 31,		Year Ended December 31,		For the Period January 29, 2011 to December 31, 2011
		2013		2012
	Stock options	$	15	$	15	$	13
	Restricted share units		42		28		18
	Employee stock purchase plans		5		4		2
	Total	$	62	$	47	$	33
	As of December 31, 2013, we had unrecognized pretax compensation expense of $35 million related to nonvested Comcast stock options and unrecognized pretax compensation expense of $98 million related to nonvested Comcast restricted share units (“RSUs”) that will be recognized over a weighted-average period of approximately 2.2 years and 1.7 years, respectively.
	Comcast maintains share-based compensation plans that primarily consist of awards of stock options and RSUs to certain employees and directors as part of its approach to long-term incentive compensation. Awards generally vest over a period of 5 years and in the case of stock options, have a 10 year term. Additionally, through the employee stock purchase plans, employees are able to purchase shares of Comcast Class A common stock at a discount through payroll deductions. Certain of our employees participate in these plans and the expense associated with their participation is settled in cash with Comcast.
	The cost associated with Comcast's share-based compensation is based on an award's estimated fair value at the date of grant and is recognized over the period in which any related services are provided. Comcast uses the Black-Scholes option pricing model to estimate the fair value of stock option awards. RSUs are valued based on the closing price of Comcast Class A common stock on the date of grant and are discounted for the lack of dividends, if any, during the vesting period. The table below presents the weighted-average fair value on the date of grant of RSUs and Class A common stock options awarded under Comcast's various plans to employees of NBCUniversal and the related weighted-average valuation assumptions.
			Successor
			Year Ended December 31,			Year Ended December 31,			For the Period January 29, 2011 to December 31,
			2013			2012			2011
	RSUs fair value		$	37.79		$	27.51		$	21.75
	Stock options fair value		$	8.86		$	7.42		$	6.77
	Stock Option Valuation Assumptions:
		Dividend yield		1.9	%		2.2	%		1.8	%
		Expected volatility		25.2	%		29	%		28.5	%
		Risk-free interest rate		1.3	%		1.7	%		2.6	%
		Expected option life (in years)		7			7			7

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Taxes	'
	Note 15: Income Taxes
	Components of Income Tax Expense
	Year ended December 31 (in millions)			2013		2012		2011
	Current expense (benefit):
		Federal	$	3,183	$	3,004	$	1,480
		State		581		432		359
		Foreign		200		169		153
				3,964		3,605		1,992
	Deferred expense (benefit):
		Federal		-76		160		658
		State		108		-40		371
		Foreign		-16		19		29
				16		139		1,058
	Income tax expense		$	3,980	$	3,744	$	3,050
	Our income tax expense differs from the federal statutory amount because of the effect of the items detailed in the table below.
	Year ended December 31 (in millions)		2013		2012		2011
	Federal tax at statutory rate	$	3,890	$	4,063	$	2,872
	State income taxes, net of federal benefit		319		178		354
	Foreign income taxes, net of federal credit		15		92		89
	Nontaxable income attributable to noncontrolling interests		-103		-620		-410
	Adjustments to uncertain and effectively settled tax positions, net		58		114		77
	Accrued interest on uncertain and effectively settled tax positions, net		114		23		66
	Other		-313		-106		2
	Income tax expense	$	3,980	$	3,744	$	3,050
	We base our provision for income taxes on our current period income, changes in our deferred income tax assets and liabilities, income tax rates, changes in estimates of our uncertain tax positions, and tax planning opportunities available in the jurisdictions in which we operate. We recognize deferred tax assets and liabilities when there are temporary differences between the financial reporting basis and tax basis of our assets and liabilities and for the expected benefits of using net operating loss carryforwards. When a change in the tax rate or tax law has an impact on deferred taxes, we apply the change based on the years in which the temporary differences are expected to reverse. We record the change in our consolidated financial statements in the period of enactment.
	Income tax consequences that arise in connection with a business combination include identifying the tax basis of assets and liabilities acquired and any contingencies associated with uncertain tax positions assumed or resulting from the business combination. Deferred tax assets and liabilities related to temporary differences of an acquired entity are recorded as of the date of the business combination and are based on our estimate of the ultimate tax basis that will be accepted by the various taxing authorities. We record liabilities for contingencies associated with prior tax returns filed by the acquired entity based on criteria set forth in the appropriate accounting guidance. We adjust the deferred tax accounts and the liabilities periodically to reflect any revised estimated tax basis and any estimated settlements with the various taxing authorities. The effects of these adjustments are recorded to income tax expense.
	From time to time, we engage in transactions in which the tax consequences may be subject to uncertainty. In these cases, we evaluate our tax positions using the recognition threshold and the measurement attribute in accordance with the accounting guidance related to uncertain tax positions. Examples of these transactions include business acquisitions and dispositions, including consideration paid or received in connection with these transactions, and certain financing transactions. Significant judgment is required in assessing and estimating the tax consequences of these transactions. We determine whether it is more likely than not that a tax position will be sustained on examination, including the resolution of any related appeals or litigation processes, based on the technical merits of the position. A tax position that meets the more-likely-than-not recognition threshold is measured to determine the amount of benefit to be recognized in our financial statements. We classify interest and penalties, if any, associated with our uncertain tax positions as a component of income tax expense.
	NBCUniversal
	For U.S. federal income tax purposes, NBCUniversal Holdings is treated as a partnership and NBCUniversal is disregarded as an entity separate from NBCUniversal Holdings. Accordingly, neither NBCUniversal Holdings nor NBCUniversal and its subsidiaries incur any material current or deferred domestic income taxes. Following the close of the Redemption Transaction in March 2013, the taxable income of NBCUniversal Holdings and NBCUniversal is allocable entirely to us.
	We are indemnified by GE for any income tax liability attributable to the NBCUniversal contributed businesses for periods prior to the date of the 2011 NBCUniversal Transaction and also for any income tax liability attributable to NBCUniversal Enterprise for periods prior to the date of the Redemption Transaction. We have indemnified GE for any income tax liability attributable to the Comcast Content Business for periods prior to the date of the 2011 NBCUniversal Transaction.
	Current and deferred foreign income taxes are incurred by NBCUniversal's foreign subsidiaries. In 2013, 2012, and 2011, NBCUniversal had foreign income before taxes of $524 million, $434 million and $476 million, respectively, on which foreign income tax expense was recorded. We recorded U.S. income tax expense on our allocable share of NBCUniversal's income before domestic and foreign taxes, which was reduced by a U.S. tax credit equal to our allocable share of NBCUniversal's foreign income tax expense.
	Components of Net Deferred Tax Liability
	December 31 (in millions)			2013		2012
	Deferred Tax Assets:
		Net operating loss carryforwards	$	495	$	491
		Differences between book and tax basis of long-term debt		117		109
		Nondeductible accruals and other		3,588		1,771
		Less: Valuation allowance		405		355
				3,795		2,016
	Deferred Tax Liabilities:
		Differences between book and tax basis of property and equipment and intangible assets		34,044		29,185
		Differences between book and tax basis of investments		473		848
		Differences between book and tax basis of indexed debt securities		610		587
		Differences between book and tax basis of foreign subsidiaries and undistributed foreign earnings		367		-
		Differences between book and tax outside basis of NBCUniversal		-		1,413
				35,494		32,033
	Net deferred tax liability		$	31,699	$	30,017
	Changes in net deferred income tax liabilities in 2013 that were not recorded as deferred income tax expense are primarily related to increases of $1.6 billion associated with the Redemption Transaction and increases of $25 million related to items included in other comprehensive income (loss). Our net deferred tax liability includes $23 billion related to cable franchise rights that will remain unchanged unless we recognize an impairment or dispose of a cable franchise.
	Net deferred tax assets included in current assets are primarily related to our current investments and current liabilities. As of December 31, 2013, we had federal net operating loss carryforwards of $176 million and various state net operating loss carryforwards that expire in periods through 2033. As of December 31, 2013, we also had foreign net operating loss carryforwards of $279 million that are related to the foreign operations of NBCUniversal, the majority of which expire in periods through 2023. The determination of the realization of the state and foreign net operating loss carryforwards is dependent on our subsidiaries' taxable income or loss, apportionment percentages, and state and foreign laws that can change from year to year and impact the amount of such carryforwards. We recognize a valuation allowance if we determine it is more likely than not that some portion, or all, of a deferred tax asset will not be realized. As of December 31, 2013 and 2012, our valuation allowance was related primarily to state and foreign net operating loss carryforwards. In 2013, 2012 and 2011, income tax expense attributable to share-based compensation of $244 million, $164 million and $38 million, respectively, was allocated to shareholders' equity.
	Uncertain Tax Positions
	Our uncertain tax positions as of December 31, 2013 totaled $1.7 billion, which excludes the federal benefits on state tax positions that were recorded as deferred income taxes. Included in our uncertain tax positions was $283 million related to tax positions of NBCUniversal and NBCUniversal Enterprise for which we have been indemnified by GE. If we were to recognize the tax benefit for our uncertain tax positions in the future, $980 million would impact our effective tax rate and the remaining amount would increase our deferred income tax liability. The amount and timing of the recognition of any such tax benefit is dependent on the completion of our tax examinations and the expiration of statutes of limitations. A majority of the amount of our uncertain tax positions relates to positions taken in years before 2007.
	Reconciliation of Unrecognized Tax Benefits
	(in millions)		2013		2012		2011
	Balance, January 1	$	1,573	$	1,435	$	1,251
	Additions based on tax positions related to the current year		90		154		87
	Additions based on tax positions related to prior years		201		79		75
	Additions from acquired subsidiaries		268		-		57
	Reductions for tax positions of prior years		-141		-60		-22
	Reductions due to expiration of statutes of limitations		-3		-3		-5
	Settlements with taxing authorities		-287		-32		-8
	Balance, December 31	$	1,701	$	1,573	$	1,435
	As of December 31, 2013 and 2012, our accrued interest associated with tax positions was $780 million and $721 million, respectively. As of December 31, 2013 and 2012, $42 million and $11 million, respectively, of these amounts were related to tax positions of NBCUniversal and NBCUniversal Enterprise for which we have been indemnified by GE.
	During 2013, the IRS completed its examination of our income tax returns for the years 2009 through 2011. During 2013, we effectively settled federal tax disputes related to prior periods. These settlements did not have a material impact on our income tax expense.
Various states are examining our tax returns through 2011. The tax years of our state tax returns currently under examination vary by state. The majority of the periods under examination relate to tax years 2000 and forward, with a select few dating back to 1993.
It is reasonably possible that certain statutes of limitations for the years 2000 through 2006 will expire within the next 12 months that could result in a decrease to our uncertain tax positions.
NBCUniversal Media, LLC [Member]	'
Income Taxes	'
	Note 14: Income Taxes
	Components of Income Tax Expense
			Successor
							For the Period January 29, 2011 to December 31,
			Year Ended December 31,		Year Ended December 31,
	(in millions)		2013		2012		2011
	Foreign
		Current income tax expense	$	77	$	69	$	53
		Deferred income tax expense		-16		16		29
		Withholding tax expense		123		103		100
	U.S. domestic tax expense			22		9		3
	Income tax expense		$	206	$	197	$	185
	We are a limited liability company, and our company is disregarded for U.S. federal income tax purposes as an entity separate from NBCUniversal Holdings, a tax partnership. NBCUniversal and our subsidiaries are not expected to incur any significant current or deferred U.S. domestic income taxes. Our tax liability is comprised primarily of withholding tax on foreign licensing activity and income taxes on foreign earnings. As a result of our tax status, the deferred tax assets and liabilities included in our consolidated balance sheet at December 31, 2013 and 2012 were not material.
	In jurisdictions in which we are subject to income taxes, we base our provision for income taxes on our current period income, changes in our deferred income tax assets and liabilities, income tax rates, changes in estimates of our uncertain tax positions, and tax planning opportunities available in the jurisdictions in which we operate. We recognize deferred tax assets and liabilities when there are temporary differences between the financial reporting basis and tax basis of our assets and liabilities and for the expected benefits of using net operating loss carryforwards. When a change in the tax rate or tax law has an impact on deferred taxes, we apply the change based on the years in which the temporary differences are expected to reverse. We record the change in our consolidated financial statements in the period of enactment.
	We classify interest and penalties, if any, associated with our uncertain tax positions as a component of income tax expense.
	Uncertain Tax Positions
	We retain liabilities for uncertain tax positions where we are the tax filer of record. GE and Comcast have indemnified NBCUniversal Holdings and us with respect to our income tax obligations attributable to periods prior to the close of the Joint Venture transaction, including indemnification of uncertain tax positions relating to filings made prior to the close of the Joint Venture transaction. The liabilities for uncertain tax positions included in our consolidated balance sheet were not material as of December 31, 2013 and 2012.
	Various domestic and foreign taxing authorities are examining our tax returns through 2012. The majority of the periods under examination relate to tax years 2004 and forward. All periods prior to January 28, 2011 that are subject to audit are covered by the indemnification from GE or Comcast.

Supplemental_Financial_Informa

Supplemental Financial Information	12 Months Ended
	Dec. 31, 2013
Supplemental Financial Information	'
	Note 16: Supplemental Financial Information
	Receivables
	December 31 (in millions)		2013		2012
	Receivables, gross	$	6,972	$	6,026
	Less: Allowance for returns and customer incentives		375		307
	Less: Allowance for doubtful accounts		221		198
	Receivables, net	$	6,376	$	5,521
	In addition to the amounts in the table above, noncurrent receivables of $488 million and $641 million, as of December 31, 2013 and 2012, respectively, are included in other noncurrent assets, net that primarily relate to the licensing of our television and film productions to third parties.
	Cash Payments for Interest and Income Taxes
	Year ended December 31 (in millions)		2013		2012		2011
	Interest	$	2,355	$	2,314	$	2,441
	Income taxes	$	3,946	$	2,841	$	1,626
	Noncash Investing and Financing Activities
	During 2013:
	• we acquired GE's remaining 49% common equity interest in NBCUniversal Holdings for total consideration of $16.7 billion, which included noncash consideration of $6 billion that was comprised of $4 billion aggregate principal amount of senior notes issued by NBCUniversal Enterprise, $1.25 billion of borrowings under NBCUniversal Enterprise's credit facility and $725 million aggregate liquidation preference of NBCUniversal Enterprise Series A cumulative preferred stock (see Note 4 for additional information on the Redemption Transaction)
	• we acquired $872 million of property and equipment and intangible assets that were accrued but unpaid
	• we recorded a liability of $509 million for a quarterly cash dividend of $0.195 per common share paid in January 2014
	• we used $1.4 billion of equity securities to settle a portion of our obligations under prepaid forward sale agreements
	• we closed a transaction with Liberty Media that included, among other things, the delivery of Liberty Media shares owned by us in exchange for Liberty Media's interests in one of NBCUniversal's contractual obligations (see Note 6 for additional information)
	During 2012:
	• we acquired $757 million of property and equipment and intangible assets that were accrued but unpaid
	• we recorded a liability of $430 million for a quarterly cash dividend of $0.1625 per common share paid in January 2013
	• NBCUniversal entered into a capital lease transaction that resulted in an increase in property and equipment and debt of $85 million
	During 2011:
	• we acquired 51% of NBCUniversal Holdings on January 28, 2011 for cash and a 49% interest in the Comcast Content Business (see Note 4 for additional information on the NBCUniversal transaction)
	• the fair value of NBCUniversal's previously held equity interest in Universal Orlando was accounted for as noncash consideration in the application of acquisition accounting for the Universal Orlando transaction (see Note 4 for additional information on the Universal Orlando transaction)
	• we acquired $1 billion of property and equipment and intangible assets that were accrued but unpaid
	• we recorded a liability of $305 million for a quarterly cash dividend of $0.1125 per common share paid in January 2012
NBCUniversal Media, LLC [Member]	'
Supplemental Financial Information	'
	Note 15: Supplemental Financial Information
	Receivables
		Successor
	December 31 (in millions)		2013		2012
	Receivables, gross	$	5,348	$	4,381
	Less: Allowance for returns and customer incentives		372		307
	Less: Allowance for doubtful accounts		65		46
	Receivables, net	$	4,911	$	4,028
	In addition to the amounts in the table above, noncurrent receivables of $488 million and $641 million, as of December 31, 2013 and 2012, respectively, are included in other noncurrent assets, net that primarily relate to the licensing of our television and film productions to third parties.
	Cash Payments for Interest and Income Taxes
		Successor						Predecessor
		Year Ended December 31,		Year Ended December 31,			For the Period January 29, 2011 to December 31,		For the Period January 1, 2011 to January 28,
	(in millions)	2013		2012			2011		2011
	Interest	$	462	$	461	$	444	$	1
	Income taxes	$	205	$	169	$	161	$	493
	Other Cash Flow Information
	As of January 28, 2011 (in millions)
	Cash and cash equivalents at end of Predecessor period	$	470
	Comcast Content Business contributed cash balances		38
	Cash and cash equivalents at beginning of Successor period	$	508
	Noncash Investing and Financing Activities
	During 2013:
	we acquired $306 million of property and equipment and intangible assets that were accrued but unpaid
	During 2012:
	we entered into a capital lease transaction that resulted in an increase in property and equipment and debt of $85 million
	For the period January 28, 2011 through December 31, 2011:
	Comcast contributed the Comcast Content Business to NBCUniversal as part of the Joint Venture transaction (see Note 3 for additional information on the Joint Venture transaction)
	the fair value of our previously held equity interest in Universal Orlando was accounted for as noncash consideration in the application of acquisition accounting for the Universal Orlando transaction (see Note 3 for additional information on the Universal Orlando transaction)
	we acquired $339 million of intellectual property rights that were accrued and unpaid

Receivables_Monetization

Receivables Monetization	12 Months Ended
	Dec. 31, 2013
Receivables Monetization	'
	Note 17: Receivables Monetization
	In December 2013, NBCUniversal terminated its programs under which it monetized certain of its accounts receivable with a syndicate of banks. In connection with these terminations, NBCUniversal remitted final payments to the third-party banks that totaled $1.442 billion (the “termination payments”) in order to acquire $1.078 billion of accounts receivables that had been monetized and remained uncollected as of the date of the terminations and settle $364 million of cash receipts that we had collected and had not yet remitted to the banks. The termination payments are included within net cash provided by operating activities in our consolidated statement of cash flows.
	Prior to the terminations, we accounted for receivables monetized through these programs as sales in accordance with the appropriate accounting guidance. We received deferred consideration from the assets sold in the form of a receivable, which was funded by residual cash flows after the senior interests had been fully paid. As of December 31, 2012, the deferred consideration was included in receivables, net at its initial fair value, which reflects the net cash flows we expected to receive related to those interests.
	Receivables Monetized and Deferred Consideration
	December 31 (in millions)		2012
	Monetized receivables sold	$	791
	Deferred consideration	$	274
	In addition to the amounts presented above, we had $882 million payable to our monetization programs as of December 31, 2012. These amounts represented cash receipts that were not yet remitted to the monetization programs and were recorded to accounts payable and accrued expenses related to trade creditors.
	The net cash payments on transfers that are included within net cash provided by operating activities in our consolidated statement of cash flows were $86 million and $237 million in 2012 and 2011, respectively. The receivables monetization programs did not have a material effect on our consolidated statement of income for the periods presented.
NBCUniversal Media, LLC [Member]	'
Receivables Monetization	'
	Note 16: Receivables Monetization
	In December 2013, we terminated the programs under which we monetized certain of our accounts receivable with a syndicate of banks. In connection with these terminations, we remitted final payments to the third-party banks that totaled $1.442 billion (the “termination payments”) in order to acquire $1.078 billion of accounts receivables that had been monetized and remained uncollected as of the date of the terminations and settle $364 million of cash receipts that we had collected and had not yet remitted to the banks. The termination payments are included within net cash provided by operating activities in our consolidated statement of cash flows.
	Prior to the terminations, we accounted for receivables monetized through these programs as sales in accordance with the appropriate accounting guidance. We received deferred consideration from the assets sold in the form of a receivable, which was funded by residual cash flows after the senior interests had been fully paid. As of December 31, 2012, the deferred consideration was included in receivables, net at its initial fair value, which reflects the net cash flows we expected to receive related to those interests.
	Receivables Monetized and Deferred Consideration
		Successor
	December 31 (in millions)		2012
	Monetized receivables sold	$	791
	Deferred consideration	$	274
	In addition to the amounts presented above, we had $882 million payable to our monetization programs as of December 31, 2012. These amounts represented cash receipts that were not yet remitted to the monetization programs and were recorded to accounts payable and accrued expenses related to trade creditors.
	The net cash payments on transfers that are included within net cash provided by operating activities in our consolidated statement of cash flows were $86 million and $237 million in 2012 and 2011, respectively. The receivables monetization programs did not have a material effect on our consolidated statement of income for the periods presented.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments and Contingencies	'
	Note 18: Commitments and Contingencies
	Commitments
	NBCUniversal enters into long-term commitments with third parties in the ordinary course of its business, including commitments to acquire film and television programming, creative talent and employment agreements, and various other television-related commitments. Many of NBCUniversal's employees, including writers, directors, actors, technical and production personnel, and others, as well as some of its on-air and creative talent, are covered by collective bargaining agreements or works councils. As of December 31, 2013, the total number of NBCUniversal full-time, part-time and hourly employees on its payroll covered by collective bargaining agreements was 7,200 full-time equivalent employees. Of this total, approximately 19% of these full-time equivalent employees were covered by collective bargaining agreements that have expired or are scheduled to expire during 2014.
	We, through Comcast-Spectacor, have employment agreements with both players and coaches of the Philadelphia Flyers. Certain of these employment agreements, which provide for payments that are guaranteed regardless of employee injury or termination, are covered by disability insurance if certain conditions are met.
	The table below summarizes our minimum annual programming and talent commitments and our minimum annual rental commitments for office space, equipment and transponder service agreements under operating leases. Programming and talent commitments include acquired film and television programming, including U.S. television rights to the future Olympic Games through 2020, Sunday Night Football on NBC through the 2022-23 season, and other programming commitments, as well as our various contracts with creative talent and employment agreements.
	As of December 31, 2013 (in millions)		Programming and Talent Commitments		Operating Leases
	2014	$	4,899	$	385
	2015	$	3,190	$	335
	2016	$	4,039	$	293
	2017	$	2,755	$	252
	2018	$	3,672	$	206
	Thereafter	$	20,522	$	673
	The table below presents our rent expense charged to operations.
	Year ended December 31 (in millions)		2013		2012		2011
	Rent expense	$	616	$	688	$	570
	Contingencies
	Antitrust Cases
	We are defendants in two purported class actions originally filed in December 2003 in the United States District Courts for the District of Massachusetts and the Eastern District of Pennsylvania. The potential class in the Massachusetts case, which has been transferred to the Eastern District of Pennsylvania, is our customer base in the “Boston Cluster” area, and the potential class in the Pennsylvania case is our customer base in the “Philadelphia and Chicago Clusters,” as those terms are defined in the complaints. In each case, the plaintiffs allege that certain customer exchange transactions with other cable providers resulted in unlawful horizontal market restraints in those areas and seek damages under antitrust statutes, including treble damages.
	Classes of Chicago Cluster and Philadelphia Cluster customers were certified in October 2007 and January 2010, respectively. We appealed the class certification in the Philadelphia Cluster case to the Third Circuit Court of Appeals, which affirmed the class certification in August 2011. In June 2012, the U.S. Supreme Court granted our petition to review the Third Circuit Court of Appeals' ruling and in March 2013, the Supreme Court ruled that the class had been improperly certified and reversed the judgment of the Third Circuit. The matter has been returned to the District Court for action consistent with the Supreme Court's opinion. In August 2013, a plaintiff in the Philadelphia Cluster case moved to certify a new, smaller class. The District Court denied our September 2013 motion to strike the plaintiffs' motion on procedural grounds, and a decision on the plaintiffs' motion is expected in 2014. The plaintiffs' claims concerning the other two clusters are stayed pending determination of the Philadelphia Cluster claims.
	In addition, we are the defendant in 22 purported class actions filed in federal district courts throughout the country. All of these actions have been consolidated by the Judicial Panel on Multidistrict Litigation in the United States District Court for the Eastern District of Pennsylvania for pre-trial proceedings. In a consolidated complaint filed in November 2009 on behalf of all plaintiffs in the multidistrict litigation, the plaintiffs allege that we improperly “tie” the rental of set-top boxes to the provision of premium cable services in violation of Section 1 of the Sherman Antitrust Act, various state antitrust laws and unfair/deceptive trade practices acts in California, Illinois and Alabama. The plaintiffs also allege a claim for unjust enrichment and seek relief on behalf of a nationwide class of our premium cable customers and on behalf of subclasses consisting of premium cable customers from California, Alabama, Illinois, Pennsylvania and Washington. In January 2010, we moved to compel arbitration of the plaintiffs' claims for unjust enrichment and violations of the unfair/deceptive trade practices acts of Illinois and Alabama. In September 2010, the plaintiffs filed an amended complaint alleging violations of additional state antitrust laws and unfair/deceptive trade practices acts on behalf of new subclasses in Connecticut, Florida, Minnesota, Missouri, New Jersey, New Mexico and West Virginia. In the amended complaint, plaintiffs omitted their unjust enrichment claim, as well as their state law claims on behalf of the Alabama, Illinois and Pennsylvania subclasses. In June 2011, the plaintiffs filed another amended complaint alleging only violations of Section 1 of the Sherman Antitrust Act, antitrust law in Washington and unfair/deceptive trade practices acts in California and Washington. The plaintiffs seek relief on behalf of a nationwide class of our premium cable customers and on behalf of subclasses consisting of premium cable customers from California and Washington. In July 2011, we moved to compel arbitration of most of the plaintiffs' claims and to stay the remaining claims pending arbitration. The West Virginia Attorney General also filed a complaint in West Virginia state court in July 2009 alleging that we improperly “tie” the rental of set-top boxes to the provision of digital cable services in violation of the West Virginia Antitrust Act and the West Virginia Consumer Credit and Protection Act. The Attorney General also alleges a claim for unjust enrichment/restitution. We removed the case to the United States District Court for West Virginia, and it was subsequently transferred to the United States District Court for the Eastern District of Pennsylvania and consolidated with the multidistrict litigation described above. In June 2013, a comprehensive settlement agreement for all 23 cases was submitted to the District Court for preliminary approval. Regardless of whether this settlement agreement is approved, we do not expect these cases to have a material effect on our results of operations, cash flows or financial position.
	We believe the claims in each of the pending actions described above in this item are without merit, except as otherwise set forth above, and intend to defend the actions vigorously. We cannot predict the outcome of any of the actions described above, including a range of possible loss, or how the final resolution of any such actions would impact our results of operations or cash flows for any one period or our financial position. In addition, as any action nears a trial, there is an increased possibility that the action may be settled by the parties. Nevertheless, the final disposition of any of the above actions is not expected to have a material adverse effect on our consolidated financial position, but could possibly be material to our consolidated results of operations or cash flows for any one period.
	Other
	We are a defendant in several unrelated lawsuits claiming infringement of various patents relating to various aspects of our businesses. In certain of these cases other industry participants are also defendants, and also in certain of these cases we expect that any potential liability would be in part or in whole the responsibility of our equipment and technology vendors under applicable contractual indemnification provisions. We are also subject to other legal proceedings and claims that arise in the ordinary course of our business. While the amount of ultimate liability with respect to such actions is not expected to materially affect our results of operations, cash flows or financial position, any litigation resulting from any such legal proceedings or claims could be time consuming, costly and injure our reputation.
NBCUniversal Media, LLC [Member]	'
Commitments and Contingencies	'
	Note 17: Commitments and Contingencies
	Commitments
	We enter into long-term commitments with third parties in the ordinary course of our business, including commitments to acquire film and television programming, creative talent and employment agreements, and various other television-related commitments. Many of our employees, including writers, directors, actors, technical and production personnel, and others, as well as some of our on-air and creative talent, are covered by collective bargaining agreements or works councils. As of December 31, 2013, the total number of full-time, part-time and hourly employees on our payroll covered by collective bargaining agreements was 7,200 full-time equivalent employees. Of this total, approximately 19% of these full-time equivalent employees were covered by collective bargaining agreements that have expired or are scheduled to expire during 2014.
	The table below summarizes our minimum annual programming and talent commitments and our minimum annual rental commitments for office space and equipment under operating leases. Programming and talent commitments include acquired film and television programming, including U.S. television rights to the future Olympic Games through 2020, Sunday Night Football on NBC through the 2022-23 season, and other programming commitments, as well as our various contracts with creative talent and employment agreements.
	As of December 31, 2013 (in millions)		Programming and Talent Commitments		Operating Leases
	2014	$	4,876	$	164
	2015	$	3,182	$	133
	2016	$	4,035	$	117
	2017	$	2,755	$	107
	2018	$	3,672	$	92
	Thereafter	$	20,522	$	365
	The table below presents our rent expense charged to operations.
		Successor						Predecessor
		Year Ended		Year Ended		For the Period January 29, 2011 to December 31, 2011		For the Period January 1, 2011 to January 28, 2011
		December 31,		December 31,
	(in millions)	2013		2012
	Rent expense	$	250	$	317	$	267	$	18

Financial_Data_by_Business_Seg

Financial Data by Business Segment	12 Months Ended
	Dec. 31, 2013
Financial Data by Business Segment	'
	Note 19: Financial Data by Business Segment
	We present our operations in one reportable business segment for Cable Communications and four reportable business segments for NBCUniversal. The Cable Networks, Broadcast Television, Filmed Entertainment and Theme Parks segments comprise the NBCUniversal businesses and are collectively referred to as the “NBCUniversal segments.” Our financial data by reportable business segment is presented in the tables below.
	(in millions)			Revenue(f)		Operating Income (Loss) Before Depreciation and Amortization(g)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2013
	Cable Communications(a)		$	41,836	$	17,205	$	6,394	$	10,811	$	5,403	$	132,082
	NBCUniversal
		Cable Networks		9,201		3,501		734		2,767		67		29,413
		Broadcast Television		7,120		345		98		247		65		6,723
		Filmed Entertainment		5,452		483		15		468		9		3,549
		Theme Parks		2,235		1,004		300		704		580		6,608
		Headquarters and Other(d)		31		-588		264		-852		439		6,002
		Eliminations(e)		-389		-13		-		-13		-		-556
	NBCUniversal			23,650		4,732		1,411		3,321		1,160		51,739
	Corporate and Other			600		-489		66		-555		33		8,152
	Eliminations(e)			-1,429		-14		-		-14		-		-33,160
	Comcast Consolidated		$	64,657	$	21,434	$	7,871	$	13,563	$	6,596	$	158,813
	(in millions)			Revenue(f)		Operating Income (Loss) Before Depreciation and Amortization(g)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2012
	Cable Communications(a)		$	39,604	$	16,255	$	6,405	$	9,850	$	4,921	$	127,044
	NBCUniversal
		Cable Networks		8,727		3,303		735		2,568		150		29,636
		Broadcast Television(b)		8,200		358		97		261		65		6,414
		Filmed Entertainment		5,159		79		16		63		7		3,769
		Theme Parks		2,085		953		268		685		272		6,266
		Headquarters and Other(d)		43		-603		210		-813		269		8,938
		Eliminations(e)		-402		17		-		17		-		-561
	NBCUniversal			23,812		4,107		1,326		2,781		763		54,462
	Corporate and Other			498		-376		67		-443		30		6,000
	Eliminations(e)			-1,344		-9		-		-9		-		-22,535
	Comcast Consolidated		$	62,570	$	19,977	$	7,798	$	12,179	$	5,714	$	164,971
	(in millions)			Revenue(f)		Operating Income (Loss) Before Depreciation and Amortization(g)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures
	2011
	Cable Communications(a)		$	37,226	$	15,288	$	6,395	$	8,893	$	4,806
	NBCUniversal
		Cable Networks		8,061		3,199		712		2,487		48
		Broadcast Television		5,982		124		85		39		61
		Filmed Entertainment		4,239		27		19		8		6
		Theme Parks(c)		1,874		830		201		629		154
		Headquarters and Other(d)		45		-484		168		-652		165
		Eliminations(e)		-941		-234		-53		-181		-
	NBCUniversal			19,260		3,462		1,132		2,330		434
	Corporate and Other			558		-416		93		-509		67
	Eliminations(e)			-1,202		23		16		7		-
	Comcast Consolidated		$	55,842	$	18,357	$	7,636	$	10,721	$	5,307
	(a)        For the years ended December 31, 2013, 2012 and 2011, Cable Communications segment revenue was derived from the following sources:
			2013		2012		2011
	Residential:
		Video	49.1	%	50.4	%	52.3	%
		High-speed Internet	24.7	%	24.1	%	23.5	%
		Voice	8.7	%	9	%	9.4	%
	Business services		7.7	%	6.5	%	5.2	%
	Advertising		5.2	%	5.8	%	5.4	%
	Other		4.6	%	4.2	%	4.2	%
	Total		100	%	100	%	100	%
	Subscription revenue received from customers who purchase bundled services at a discounted rate is allocated proportionally to each service based on the individual service's price on a stand-alone basis. Beginning in 2013, revenue from certain business customers, such as hotels, restaurants and bars, is presented in business services revenue rather than in video revenue. Reclassifications have been made to the prior year periods to conform to this presentation.
	For each of 2013, 2012 and 2011, 2.8% of Cable Communications revenue was derived from franchise and other regulatory fees.
	(b)        For 2012, our Broadcast Television segment included all revenue and costs and expenses associated with our broadcast of the 2012 London Olympics, which generated $120 million of operating income before depreciation and amortization. This amount reflects the settlement of a $237 million liability associated with the unfavorable Olympics contract that had been recorded through the application of acquisition accounting in 2011.
	(c)       For the period January 29, 2011 through June 30, 2011, we recorded Universal Orlando as an equity method investment in our consolidated results of operations. However, our Theme Parks segment included the results of operations for Universal Orlando for the period January 29, 2011 through June 30, 2011 to reflect our measure of operating performance for our Theme Parks segment.
	(d) NBCUniversal Headquarters and Other activities includes costs associated with overhead, allocations, personnel costs and headquarter initiatives.
	(e)       Included in Eliminations are transactions that our segments enter into with one another. The most common types of transactions are the following:
	•       our Cable Networks and Broadcast Television segments generate revenue by selling programming to our Cable Communications segment, which represents a substantial majority of the revenue elimination amount
	•       our Cable Communications segment generates revenue by selling advertising and by selling the use of satellite feeds to our Cable Networks segment
	• our Filmed Entertainment and Broadcast Television segments generate revenue by licensing content to our Cable Networks segment
•       our Cable Communications segment receives incentives offered by our Cable Networks segment in connection with its distribution of the Cable Networks' content that are recorded as a reduction to programming expenses
NBCUniversal eliminations for 2011 included the eliminations of the results of operations for Universal Orlando for the period January 29, 2011 through June 30, 2011. These amounts were not included in NBCUniversal's total and our consolidated results of operations for the period January 29, 2011 through June 30, 2011 because we recorded Universal Orlando as an equity method investment during this period.
Revenue from customers located outside of the U.S., primarily in Europe and Asia, for the years ended December 31, 2013, 2012 and 2011 was $4.8 billion, $4.5 billion and $4.1 billion, respectively. No single customer accounted for a significant amount of our revenue in any period.
We use operating income (loss) before depreciation and amortization, excluding impairment charges related to fixed and intangible assets and gains or losses from the sale of assets, if any, as the measure of profit or loss for our operating segments. This measure eliminates the significant level of noncash depreciation and amortization expense that results from the capital-intensive nature of certain of our businesses and from intangible assets recognized in business combinations. Additionally, it is unaffected by our capital structure or investment activities. We use this measure to evaluate our consolidated operating performance and the operating performance of our operating segments and to allocate resources and capital to our operating segments. It is also a significant performance measure in our annual incentive compensation programs. We believe that this measure is useful to investors because it is one of the bases for comparing our operating performance with that of other companies in our industries, although our measure may not be directly comparable to similar measures used by other companies. This measure should not be considered a substitute for operating income (loss), net income (loss) attributable to Comcast Corporation, net cash provided by operating activities, or other measures of performance or liquidity we have reported in accordance with GAAP.
NBCUniversal Media, LLC [Member]	'
Financial Data by Business Segment	'
	Note 18: Financial Data by Business Segment
	We present our operations in four reportable business segments: Cable Networks, Broadcast Television, Filmed Entertainment and Theme Parks. Our financial data by reportable business segment is presented in the tables below.
	Successor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2013
		Cable Networks	$	9,201	$	3,501	$	734	$	2,767	$	67	$	29,413
		Broadcast Television		7,120		345		98		247		65		6,723
		Filmed Entertainment		5,452		483		15		468		9		3,549
		Theme Parks		2,235		1,004		300		704		580		6,608
		Headquarters and Other(c)		31		-588		264		-852		439		6,002
		Eliminations(d)		-389		-13		-		-13		-		-556
	Total		$	23,650	$	4,732	$	1,411	$	3,321	$	1,160	$	51,739
	Successor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2012
		Cable Networks	$	8,727	$	3,303	$	735	$	2,568	$	150	$	29,636
		Broadcast Television(a)		8,200		358		97		261		65		6,414
		Filmed Entertainment		5,159		79		16		63		7		3,769
		Theme Parks		2,085		953		268		685		272		6,266
		Headquarters and Other(c)		43		-603		210		-813		269		8,938
		Eliminations(d)		-402		17		-		17		-		-561
	Total		$	23,812	$	4,107	$	1,326	$	2,781	$	763	$	54,462
	Successor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures
	For the Period January 29, 2011 to December 31, 2011
		Cable Networks	$	7,829	$	3,133	$	694	$	2,439	$	46
		Broadcast Television		5,982		124		85		39		61
		Filmed Entertainment		4,239		27		19		8		6
		Theme Parks(b)		1,874		830		201		629		154
		Headquarters and Other(c)		45		-484		114		-598		165
		Eliminations(d)		-941		-234		-		-234		-
	Total		$	19,028	$	3,396	$	1,113	$	2,283	$	432
	Predecessor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures
	For the Period January 1, 2011 to January 28, 2011
		Cable Networks	$	385	$	145	$	3	$	142	$	1
		Broadcast Television		468		-18		6		-24		1
		Filmed Entertainment		353		1		2		-1		1
		Theme Parks(b)		115		37		14		23		9
		Headquarters and Other(c)		5		-99		2		-101		4
		Eliminations(d)		-120		-31		-		-31		-
	Total		$	1,206	$	35	$	27	$	8	$	16
	For 2012, our Broadcast Television segment included all revenue and costs and expenses associated with our broadcast of the 2012 London Olympics, which generated $120 million of operating income before depreciation and amortization. This amount reflects the settlement of a $237 million liability associated with the unfavorable Olympics contract that had been recorded through the application of acquisition accounting in 2011.
	For the periods January 1, 2011 through January 28, 2011 and January 29, 2011 through June 30, 2011, our Theme Parks segment included the results of operations for Universal Orlando to reflect our measure of operating performance for our Theme Parks segment.
	Headquarters and Other activities includes costs associated with overhead, allocations, personnel costs and corporate initiatives.
	Eliminations for the periods January 1, 2011 through January 28, 2011 and January 29, 2011 through June 30, 2011 included the eliminations of the results of operations for Universal Orlando for these periods. These results were not included in our consolidated results of operations because we recorded Universal Orlando as an equity method investment during those periods.
	Also included in Eliminations are transactions that our segments enter into with one another, which consisted primarily of the licensing of film and television content from our Filmed Entertainment and Broadcast Television segments to our Cable Networks segment.
	No single customer accounted for a significant amount of revenue in any period.
	We use operating income (loss) before depreciation and amortization, excluding impairment charges related to fixed and intangible assets and gains or losses from the sale of assets, if any, as the measure of profit or loss for our operating segments. This measure eliminates the significant level of noncash amortization expense that results from intangible assets recognized in connection with the Joint Venture transaction and other business combinations. Additionally, it is unaffected by our capital structure or investment activities. We use this measure to evaluate our consolidated operating performance and the operating performance of our operating segments and to allocate resources and capital to our operating segments. It is also a significant performance measure in our annual incentive compensation programs. We believe that this measure is useful to investors because it is one of the bases for comparing our operating performance with that of other companies in our industries, although our measure may not be directly comparable to similar measures used by other companies. This measure should not be considered a substitute for operating income (loss), net income (loss) attributable to NBCUniversal, net cash provided by operating activities, or other measures of performance or liquidity we have reported in accordance with GAAP.
	We operate primarily in the United States, but also in select international markets primarily in Europe and Asia. The table below summarizes revenue by geographic location.
			Successor								Predecessor
				Year Ended December 31,		Year Ended December 31,		For the Period January 29, 2011 to December 31, 2011			For the Period January 1, 2011 to January 28, 2011
		(in millions)		2013		2012
		Revenue:
		United States	$	18,887	$	19,348	$	14,927			$	935
		Foreign	$	4,763	$	4,464	$	4,101			$	271

Quarterly_Financial_Informatio

Quarterly Financial Information	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information	'
	Note 20: Quarterly Financial Information (Unaudited)
	(in millions, except per share data)		First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Total Year
	2013
	Revenue	$	15,310	$	16,270	$	16,151	$	16,926	$	64,657
	Operating income	$	3,067	$	3,435	$	3,414	$	3,647	$	13,563
	Net income attributable to Comcast Corporation	$	1,437	$	1,734	$	1,732	$	1,913	$	6,816
	Basic earnings per common share attributable to Comcast Corporation shareholders	$	0.55	$	0.66	$	0.66	$	0.73	$	2.6
	Diluted earnings per common share attributable to Comcast Corporation shareholders	$	0.54	$	0.65	$	0.65	$	0.72	$	2.56
	Dividends declared per common share	$	0.195	$	0.195	$	0.195	$	0.195	$	0.78
	2012
	Revenue	$	14,878	$	15,211	$	16,544	$	15,937	$	62,570
	Operating income	$	2,758	$	3,079	$	3,048	$	3,294	$	12,179
	Net income attributable to Comcast Corporation	$	1,224	$	1,348	$	2,113	$	1,518	$	6,203
	Basic earnings per common share attributable to Comcast Corporation shareholders	$	0.45	$	0.5	$	0.79	$	0.57	$	2.32
	Diluted earnings per common share attributable to Comcast Corporation shareholders	$	0.45	$	0.5	$	0.78	$	0.56	$	2.28
	Dividends declared per common share	$	0.1625	$	0.1625	$	0.1625	$	0.1625	$	0.65

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information	12 Months Ended
	Dec. 31, 2013
Condensed Consolidating Financial Information [Abstract]	'
Condensed Consolidating Financial Information	'
	Note 21: Condensed Consolidating Financial Information
	Comcast Corporation (“Comcast Parent”) and four of our 100% owned cable holding company subsidiaries, Comcast Cable Communications, LLC (“CCCL Parent”), Comcast MO Group, Inc. (“Comcast MO Group”), Comcast Cable Holdings, LLC (“CCH”) and Comcast MO of Delaware, LLC (“Comcast MO of Delaware”) (collectively, the “cable guarantors”), have fully and unconditionally guaranteed each other's debt securities. Comcast MO Group, CCH and Comcast MO of Delaware are collectively referred to as the “Combined CCHMO Parents.” The debt securities within the guarantee structure total $30.9 billion, of which $11.0 billion will mature within the next five years.
	On March 27, 2013, Comcast Parent, the cable guarantors and NBCUniversal Media, LLC (referred to as “NBCUniversal Media Parent” in the tables below) entered into a series of agreements and supplemental indentures to include NBCUniversal Media, LLC as part of our existing cross-guarantee structure. As members of the cross-guarantee structure, Comcast Parent and the cable guarantors fully and unconditionally guarantee NBCUniversal Media, LLC's public debt securities, and NBCUniversal Media, LLC fully and unconditionally guarantees all of Comcast Parent's and the cable guarantors' public debt securities, as well as the $6.25 billion revolving credit facility of Comcast Parent and Comcast Cable Communications, LLC.
	Comcast Parent and the cable guarantors also fully and unconditionally guarantee NBCUniversal Enterprise's $4 billion of senior notes and its $1.35 billion credit facility due March 2018. NBCUniversal Media, LLC does not guarantee the NBCUniversal Enterprise senior notes or credit facility.
	Comcast Parent provides an unconditional subordinated guarantee of the $185 million principal amount currently outstanding of Comcast Holdings' ZONES due October 2029. Neither the cable guarantors nor NBCUniversal Media, LLC guarantee the Comcast Holdings ZONES due October 2029. None of Comcast Parent, the cable guarantors nor NBCUniversal Media, LLC guarantee the $62 million principal amount currently outstanding of Comcast Holdings' ZONES due November 2029.
	Condensed Consolidating Balance Sheet
	December 31, 2013 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Assets
		Cash and cash equivalents	$	-	$	-	$	-	$	-	$	336	$	1,382	$	-	$	1,718
		Investments		-		-		-		-		-		3,573		-		3,573
		Receivables, net		-		-		-		-		-		6,376		-		6,376
		Programming rights		-		-		-		-		-		928		-		928
		Other current assets		237		-		-		-		35		1,208		-		1,480
	Total current assets			237		-		-		-		371		13,467		-		14,075
	Film and television costs			-		-		-		-		-		4,994		-		4,994
	Investments			11		-		-		-		374		3,385		-		3,770
	Investments in and amounts due from subsidiaries eliminated upon consolidation			79,956		97,429		102,673		54,724		40,644		85,164		-460,590		-
	Property and equipment, net			220		-		-		-		-		29,620		-		29,840
	Franchise rights			-		-		-		-		-		59,364		-		59,364
	Goodwill			-		-		-		-		-		27,098		-		27,098
	Other intangible assets, net			11		-		-		-		-		17,318		-		17,329
	Other noncurrent assets, net			1,078		145		-		-		103		1,899		-882		2,343
	Total assets		$	81,513	$	97,574	$	102,673	$	54,724	$	41,492	$	242,309	$	-461,472	$	158,813
	Liabilities and Equity
		Accounts payable and accrued expenses related to trade creditors	$	8	$	-	$	-	$	-	$	-	$	5,520	$	-	$	5,528
		Accrued participations and residuals		-		-		-		-		-		1,239		-		1,239
		Accrued expenses and other current liabilities		1,371		266		180		47		323		6,678		-		8,865
		Current portion of long-term debt		2,351		-		-		-		903		26		-		3,280
	Total current liabilities			3,730		266		180		47		1,226		13,463		-		18,912
	Long-term debt, less current portion			25,170		132		1,827		1,505		10,236		5,697		-		44,567
	Deferred income taxes			-		777		-		-		59		31,840		-741		31,935
	Other noncurrent liabilities			1,919		-		-		-		931		8,675		-141		11,384
	Redeemable noncontrolling interests
		and redeemable subsidiary preferred stock		-		-		-		-		-		957		-		957
	Equity:
		Common stock		30		-		-		-		-		-		-		30
		Other shareholders’ equity		50,664		96,399		100,666		53,172		29,040		181,313		-460,590		50,664
	Total Comcast Corporation shareholders’ equity			50,694		96,399		100,666		53,172		29,040		181,313		-460,590		50,694
	Noncontrolling interests			-		-		-		-		-		364		-		364
	Total equity			50,694		96,399		100,666		53,172		29,040		181,677		-460,590		51,058
	Total liabilities and equity		$	81,513	$	97,574	$	102,673	$	54,724	$	41,492	$	242,309	$	-461,472	$	158,813
	Condensed Consolidating Balance Sheet
	December 31, 2012 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Assets
		Cash and cash equivalents	$	-	$	-	$	-	$	-	$	5,129	$	5,822	$	-	$	10,951
		Investments		-		-		-		-		-		1,464		-		1,464
		Receivables, net		-		-		-		-		3		5,518		-		5,521
		Programming rights		-		-		-		-		-		909		-		909
		Other current assets		233		-		14		4		51		844		-		1,146
	Total current assets			233		-		14		4		5,183		14,557		-		19,991
	Film and television costs			-		-		-		-		-		5,054		-		5,054
	Investments			-		-		-		-		529		5,796		-		6,325
	Investments in and amounts due from subsidiaries eliminated upon consolidation			74,227		87,630		96,853		50,242		38,464		73,298		-420,714		-
	Property and equipment, net			242		-		-		-		-		26,990		-		27,232
	Franchise rights			-		-		-		-		-		59,364		-		59,364
	Goodwill			-		-		-		-		-		26,985		-		26,985
	Other intangible assets, net			12		-		-		-		-		17,828		-		17,840
	Other noncurrent assets, net			1,130		147		1		-		152		1,650		-900		2,180
	Total assets		$	75,844	$	87,777	$	96,868	$	50,246	$	44,328	$	231,522	$	-421,614	$	164,971
	Liabilities and Equity
		Accounts payable and accrued expenses related to trade creditors	$	8	$	-	$	-	$	-	$	-	$	6,198	$	-	$	6,206
		Accrued participations and residuals		-		-		-		-		-		1,350		-		1,350
		Accrued expenses and other current liabilities		1,290		275		210		54		263		4,690		-		6,782
	Current portion of long-term debt		-		-		2,105		241		7		23		-		2,376
Total current liabilities			1,298		275		2,315		295		270		12,261		-		16,714
Long-term debt, less current portion			23,306		113		1,827		1,512		11,219		105		-		38,082
Deferred income taxes			-		754		-		-		78		30,035		-757		30,110
Other noncurrent liabilities			1,884		-		-		-		926		10,604		-143		13,271
Redeemable noncontrolling interests
	and redeemable subsidiary preferred stock		-		-		-		-		-		16,998		-		16,998
Equity:
	Common stock		31		-		-		-		-		-		-		31
	Other shareholders’ equity		49,325		86,635		92,726		48,439		31,835		161,079		-420,714		49,325
Total Comcast Corporation shareholders’ equity			49,356		86,635		92,726		48,439		31,835		161,079		-420,714		49,356
Noncontrolling interests			-		-		-		-		-		440		-		440
Total equity			49,356		86,635		92,726		48,439		31,835		161,519		-420,714		49,796
Total liabilities and equity		$	75,844	$	87,777	$	96,868	$	50,246	$	44,328	$	231,522	$	-421,614	$	164,971
Condensed Consolidating Statement of Income
For the Year Ended December 31, 2013 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
Revenue:
	Service revenue	$	-	$	-	$	-	$	-	$	-	$	64,657	$	-	$	64,657
	Management fee revenue		897		-		874		548		-		-		-2,319		-
			897		-		874		548		-		64,657		-2,319		64,657
Costs and Expenses:
	Programming and production		-		-		-		-		-		19,670		-		19,670
	Other operating and administrative		403		-		874		548		855		18,223		-2,319		18,584
	Advertising, marketing and promotion		-		-		-		-		-		4,969		-		4,969
	Depreciation		30		-		-		-		-		6,224		-		6,254
	Amortization		5		-		-		-		-		1,612		-		1,617
			438		-		874		548		855		50,698		-2,319		51,094
Operating income (loss)			459		-		-		-		-855		13,959		-		13,563
Other Income (Expense):
	Interest expense		-1,523		-11		-212		-126		-488		-214		-		-2,574
	Investment income (loss), net		-		-13		-		-		3		586		-		576
	Equity in net income (losses) of
	investees, net		7,509		7,540		7,430		5,473		3,331		1,882		-33,251		-86
	Other income (expense), net		-2		-		2		-		-1		-363		-		-364
			5,984		7,516		7,220		5,347		2,845		1,891		-33,251		-2,448
Income (loss) before income taxes			6,443		7,516		7,220		5,347		1,990		15,850		-33,251		11,115
Income tax (expense) benefit			373		9		73		44		-22		-4,457		-		-3,980
Net income (loss)			6,816		7,525		7,293		5,391		1,968		11,393		-33,251		7,135
Net (income) loss attributable to
	noncontrolling interests and redeemable subsidiary preferred stock		-		-		-		-		-		-319		-		-319
Net income (loss) attributable to
	Comcast Corporation	$	6,816	$	7,525	$	7,293	$	5,391	$	1,968	$	11,074	$	-33,251	$	6,816
Comprehensive income (loss)
	attributable to Comcast Corporation	$	6,883	$	7,521	$	7,276	$	5,392	$	2,017	$	10,969	$	-33,175	$	6,883
Condensed Consolidating Statement of Income
For the Year Ended December 31, 2012 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
Revenue:
	Service revenue	$	-	$	-	$	-	$	-	$	-	$	62,570	$	-	$	62,570
	Management fee revenue		848		-		827		516		-		-		-2,191		-
			848		-		827		516		-		62,570		-2,191		62,570
Costs and Expenses:
	Programming and production		-		-		-		-		-		19,929		-		19,929
	Other operating and administrative		401		-		827		516		899		17,381		-2,191		17,833
	Advertising, marketing and promotion		-		-		-		-		-		4,831		-		4,831
	Depreciation		30		-		-		-		-		6,120		-		6,150
	Amortization		4		-		-		-		-		1,644		-		1,648
			435		-		827		516		899		49,905		-2,191		50,391
Operating income (loss)			413		-		-		-		-899		12,665		-		12,179
Other Income (Expense):
	Interest expense		-1,430		-23		-329		-135		-430		-174		-		-2,521
	Investment income (loss), net		8		3		-		-		5		203		-		219
	Equity in net income (losses) of
	investees, net		6,858		6,536		6,665		4,909		4,402		4,014		-32,425		959
	Other income (expense), net		2		-		-		-		-14		785		-		773
			5,438		6,516		6,336		4,774		3,963		4,828		-32,425		-570
Income (loss) before income taxes			5,851		6,516		6,336		4,774		3,064		17,493		-32,425		11,609
Income tax (expense) benefit			352		7		115		47		-9		-4,256		-		-3,744
Net income (loss)			6,203		6,523		6,451		4,821		3,055		13,237		-32,425		7,865
Net (income) loss attributable to
	noncontrolling interests and redeemable subsidiary preferred stock		-		-		-		-		-		-1,662		-		-1,662
Net (income) loss attributable
	to Comcast Corporation	$	6,203	$	6,523	$	6,451	$	4,821	$	3,055	$	11,575	$	-32,425	$	6,203
Comprehensive income (loss)
	attributable to Comcast Corporation	$	6,370	$	6,523	$	6,460	$	4,821	$	3,068	$	11,703	$	-32,575	$	6,370
Condensed Consolidating Statement of Income
For the Year Ended December 31, 2011 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
Revenue:
	Service revenue	$	-	$	-	$	-	$	-	$	-	$	55,842	$	-	$	55,842
	Management fee revenue		800		-		784		488		-		-		-2,072		-
			800		-		784		488		-		55,842		-2,072		55,842
Costs and Expenses:
	Programming and production		-		-		-		-		-		16,596		-		16,596
	Other operating and administrative		420		5		784		488		678		16,343		-2,072		16,646
	Advertising, marketing and promotion		-		-		-		-		-		4,243		-		4,243
	Depreciation		29		-		-		-		-		6,011		-		6,040
	Amortization		3		-		-		-		-		1,593		-		1,596
			452		5		784		488		678		44,786		-2,072		45,121
Operating income (loss)			348		-5		-		-		-678		11,056		-		10,721
Other Income (Expense):
	Interest expense		-1,439		-32		-338		-172		-370		-154		-		-2,505
	Investment income (loss), net		3		2		-		-		-		154		-		159
	Equity in net income (losses) of
	investees, net		4,879		5,734		5,598		3,361		2,793		1,648		-24,048		-35
	Other income (expense), net		-19		1		-		-		-59		-56		-		-133
			3,424		5,705		5,260		3,189		2,364		1,592		-24,048		-2,514
Income (loss) before income taxes			3,772		5,700		5,260		3,189		1,686		12,648		-24,048		8,207
Income tax (expense) benefit			388		12		118		60		-3		-3,625		-		-3,050
Net income (loss)			4,160		5,712		5,378		3,249		1,683		9,023		-24,048		5,157
Net (income) loss attributable to
	noncontrolling interests and redeemable subsidiary preferred stock		-		-		-		-		-		-997		-		-997
Net income (loss) attributable to
	Comcast Corporation	$	4,160	$	5,712	$	5,378	$	3,249	$	1,683	$	8,026	$	-24,048	$	4,160
Comprehensive income (loss)
	attributable to Comcast Corporation	$	4,107	$	5,712	$	5,387	$	3,249	$	1,605	$	8,064	$	-24,017	$	4,107
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2013 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Net cash provided by (used in) operating activities	$	-600	$	-3	$	-151	$	-94	$	-1,102	$	16,110	$	-	$	14,160
Investing Activities:
	Net transactions with affiliates		66		3		2,248		332		-470		-2,179		-		-
	Capital expenditures		-7		-		-		-		-		-6,589		-		-6,596
	Cash paid for intangible assets		-4		-		-		-		-		-1,005		-		-1,009
	Acquisitions of real estate properties		-		-		-		-		-		-1,904		-		-1,904
	Acquisitions, net of cash acquired		-		-		-		-		-		-99		-		-99
	Proceeds from sales of businesses and investments		-		-		-		-		2		1,081		-		1,083
	Return of capital from investees		-		-		-		-		128		21		-		149
	Purchases of investments		-11		-		-		-		-3		-1,209		-		-1,223
	Other		-		-		-		-		-20		105		-		85
	Net cash provided by (used in) investing activities		44		3		2,248		332		-363		-11,778		-		-9,514
Financing Activities:
	Proceeds from (repayments of) short-term borrowings, net		1,349		-		-		-		-		-4		-		1,345
	Proceeds from borrowings		2,933		-		-		-		-		-		-		2,933
	Repurchases and repayments of debt		-		-		-2,097		-238		-88		-21		-		-2,444
	Repurchases and retirements of common stock		-2,000		-		-		-		-		-		-		-2,000
	Dividends paid		-1,964		-		-		-		-		-		-		-1,964
	Issuances of common stock		40		-		-		-		-		-		-		40
	Purchase of NBCUniversal noncontrolling common equity interest		-		-		-		-		-3,200		-7,561		-		-10,761
	Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock		-		-		-		-		-		-215		-		-215
	Settlement of Station Venture liability		-		-		-		-		-		-602		-		-602
	Other		198		-		-		-		-40		-369		-		-211
	Net cash provided by (used in) financing activities		556		-		-2,097		-238		-3,328		-8,772		-		-13,879
Increase (decrease) in cash and cash equivalents			-		-		-		-		-4,793		-4,440		-		-9,233
Cash and cash equivalents, beginning of year			-		-		-		-		5,129		5,822		-		10,951
Cash and cash equivalents, end of year		$	-		-		-		-		336		1,382		-		1,718
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2012 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Net cash provided by (used in) operating activities	$	-362	$	-7	$	-177	$	-114	$	-1,347	$	16,861	$	-	$	14,854
Investing Activities:
	Net transactions with affiliates		3,845		206		177		667		4,850		-9,745		-		-
	Capital expenditures		-10		-		-		-		-		-5,704		-		-5,714
	Cash paid for intangible assets		-6		-		-		-		-		-917		-		-923
	Acquisitions, net of cash acquired		-		-		-		-		-		-90		-		-90
	Proceeds from sales of businesses and investments		-		-		-		-		-		3,102		-		3,102
	Return of capital from investees		-		-		-		-		-		2,362		-		2,362
	Purchases of investments		-		-		-		-		-19		-278		-		-297
	Other		-		3		-		-		-22		93		-		74
	Net cash provided by (used in) investing activities		3,829		209		177		667		4,809		-11,177		-		-1,486
Financing Activities:
	Proceeds from (repayments of) short-term borrowings, net		-1		-		-		-		-550		7		-		-544
	Proceeds from borrowings		2,536		-		-		-		1,995		13		-		4,544
	Repurchases and repayments of debt		-1,726		-202		-		-553		-2		-398		-		-2,881
	Repurchases and retirements of common stock		-3,000		-		-		-		-		-		-		-3,000
	Dividends paid		-1,608		-		-		-		-		-		-		-1,608
	Issuances of common stock		233		-		-		-		-		-		-		233
	Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock		-		-		-		-		-		-691		-		-691
	Other		99		-		-		-		-14		-175		-		-90
	Net cash provided by (used in) financing activities		-3,467		-202		-		-553		1,429		-1,244		-		-4,037
Increase (decrease) in cash and cash equivalents			-		-		-		-		4,891		4,440		-		9,331
Cash and cash equivalents, beginning of year			-		-		-		-		238		1,382		-		1,620
Cash and cash equivalents, end of year		$	-	$	-	$	-	$	-	$	5,129	$	5,822	$	-	$	10,951
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2011 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Net cash provided by (used in) operating activities	$	-513	$	-19	$	-209	$	-131	$	-638	$	15,855	$	-	$	14,345
Investing Activities:
	Net transactions with affiliates		4,615		19		1,209		131		247		-6,221		-		-
	Capital expenditures		-7		-		-		-		-		-5,300		-		-5,307
	Cash paid for intangible assets		-2		-		-		-		-		-952		-		-954
	Acquisitions, net of cash acquired		-		-		-		-		295		-6,702		-		-6,407
	Proceeds from sales of businesses and investments		-		-		-		-		3		274		-		277
	Return of capital from investees		-		-		-		-		-		37		-		37
	Purchases of investments		-		-		-		-		-4		-131		-		-135
	Other		-		-		-		-		-		-19		-		-19
	Net cash provided by (used in) investing activities		4,606		19		1,209		131		541		-19,014		-		-12,508
Financing Activities:
	Proceeds from (repayments of) short-term borrowings, net		-4		-		-		-		550		-2		-		544
	Repurchases and repayments of debt		-1,095		-		-1,000		-		-		-1,121		-		-3,216
	Repurchases and retirements of common stock		-2,141		-		-		-		-		-		-		-2,141
	Dividends paid		-1,187		-		-		-		-		-		-		-1,187
	Issuances of common stock		283		-		-		-		-		-		-		283
	Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock		-		-		-		-		-		-325		-		-325
	Other		51		-		-		-		-215		5		-		-159
	Net cash provided by (used in) financing activities		-4,093		-		-1,000		-		335		-1,443		-		-6,201
Increase (decrease) in cash and cash equivalents			-		-		-		-		238		-4,602		-		-4,364
Cash and cash equivalents, beginning of year			-		-		-		-		-		5,984		-		5,984
Cash and cash equivalents, end of year		$	-	$	-	$	-	$	-	$	238	$	1,382	$	-	$	1,620

Schedule_II_Valuation_and_Qual

Schedule II Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2013
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	'
	Comcast Corporation and Subsidiaries
	Schedule II — Valuation and Qualifying Accounts
	Year ended December 31, 2013, 2012 and 2011
	Year Ended December 31 (in millions)			Balance at Beginning of Year		Additions Charged to Costs and Expenses		Deductions from Reserves		Balance at End of Year
	2013
		Allowance for doubtful accounts	$	198	$	317	$	294	$	221
		Allowance for returns and customer incentives		307		528		460		375
		Valuation allowance on deferred tax assets		355		71		21		405
	2012
		Allowance for doubtful accounts	$	202	$	293	$	297	$	198
		Allowance for returns and customer incentives		425		599		717		307
		Valuation allowance on deferred tax assets		297		61		3		355
	2011
		Allowance for doubtful accounts	$	173	$	306	$	277	$	202
		Allowance for returns and customer incentives		-		536		111		425
		Valuation allowance on deferred tax assets		207		103		13		297
NBCUniversal Media, LLC [Member]	'
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	'
	NBCUniversal Media, LLC
	Schedule II — Valuation and Qualifying Accounts
	(in millions)			Balance at Beginning of Period		Additions Charged to Costs and Expenses		Deductions from Reserves		Balance at End of Period
	Successor
	Year ended December 31, 2013
		Allowance for doubtful accounts	$	46	$	33	$	14	$	65
		Allowance for returns and customer incentives		307		525		460		372
		Valuation allowance on deferred tax assets		73		8		21		60
	Year ended December 31, 2012
		Allowance for doubtful accounts	$	34	$	19	$	7	$	46
		Allowance for returns and customer incentives		425		599		717		307
		Valuation allowance on deferred tax assets		53		23		3		73
	Period January 29, 2011 through December 31, 2011
		Allowance for doubtful accounts	$	7	$	35	$	8	$	34
		Allowance for returns and customer incentives		-		536		111		425
		Valuation allowance on deferred tax assets		57		9		13		53

Accounting_Policies_Policy

Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2013
Basis of Presentation	'
	Basis of Presentation
	The accompanying consolidated financial statements include all entities in which we have a controlling voting interest (“subsidiaries”) and variable interest entities (“VIEs”) required to be consolidated in accordance with generally accepted accounting principles in the United States (“GAAP”).
Foreign Currency Translation	'
	We translate assets and liabilities of our foreign subsidiaries where the functional currency is the local currency, primarily the euro and the British pound, into U.S. dollars at the exchange rate in effect as of the balance sheet date. The related translation adjustments are recorded as a component of accumulated other comprehensive income (loss). We translate revenue and expenses using average monthly exchange rates, and the related foreign currency transaction gains and losses are included in our consolidated statement of income.
Cash Equivalents	'
	Cash Equivalents
	The carrying amounts of our cash equivalents approximate their fair value. Our cash equivalents consist primarily of money market funds and U.S. government obligations, as well as commercial paper and certificates of deposit with maturities of less than three months when purchased.
Film And Television Costs	'
	Capitalization of Film and Television Costs
	We capitalize film and television production costs, including direct costs, production overhead, print costs, development costs and interest. We amortize capitalized film and television production costs, including acquired libraries, and accrue costs associated with participation and residual payments to programming and production expense. We generally record the amortization and the accrued costs using the individual film forecast computation method, which amortizes such costs in the same ratio as the associated ultimate revenue. Estimates of total revenue and total costs are based on anticipated release patterns, public acceptance and historical results for similar productions. Unamortized film and television costs, including acquired film and television libraries, are stated at the lower of unamortized cost or fair value. We do not capitalize costs related to the distribution of a film to movie theaters or the licensing or sale of a film or television production, which are primarily costs associated with the marketing and distribution of film and television programming.
	In determining the estimated lives and method of amortization of acquired film and television libraries, we generally use the method and the life that most closely follow the undiscounted cash flows over the estimated life of the asset.
	Upon the occurrence of an event or a change in circumstance that was known or knowable as of the balance sheet date and that indicates the fair value of a film is less than its unamortized costs, we determine the fair value of the film and record an impairment charge for the amount by which the unamortized capitalized costs exceed the film's fair value.
	We enter into arrangements with third parties to jointly finance and distribute certain of our film productions. These arrangements, which are referred to as cofinancing arrangements, can take various forms. In most cases, the arrangement involves the grant of an economic interest in a film to a third-party investor. The number of investors and the terms of these arrangements can vary, although in most cases an investor assumes full risk for the portion of the film acquired in these arrangements. We account for the proceeds received from a third-party investor under these arrangements as a reduction to our capitalized film costs. In these arrangements, the investor owns an undivided copyright interest in the film and, therefore, in each period we record either a charge or a benefit to programming and production expense to reflect the estimate of the third-party investor's interest in the profit or loss of the film. The estimate of the third-party investor's interest in the profit or loss of a film is determined using the ratio of actual revenue earned to date to the ultimate revenue expected to be recognized over the film's useful life.
	We capitalize the costs of programming content that we license but do not own, including rights to multiyear live-event sports programming, at the earlier of when payments are made for the programming or when the license period begins and the content is available for use. We amortize capitalized programming costs as the associated programs are broadcast. We amortize multiyear, live-event sports programming rights using the ratio of the current period revenue to the estimated total remaining revenue or under the terms of the contract.
	Acquired programming costs are recorded at the lower of unamortized cost or net realizable value on a program by program, package, channel or daypart basis. A daypart is an aggregation of programs broadcast during a particular time of day or programs of a similar type. Acquired programming used in our Cable Networks segment is primarily tested on a channel basis for impairment, whereas acquired programming used in our Broadcast Television segment is tested on a daypart basis. If we determine that the estimates of future cash flows are insufficient or if there is no plan to broadcast certain programming, we recognize an impairment charge to programming and production expense.
Investments	'
	Fair Value Method
	We classify publicly traded investments that are not accounted for under the equity method as available-for-sale (“AFS”) or trading securities and record them at fair value. For AFS securities, we record unrealized gains or losses resulting from changes in fair value between measurement dates as a component of other comprehensive income (loss), except when we consider declines in value to be other than temporary. For trading securities, we record unrealized gains or losses resulting from changes in fair value between measurement dates as a component of investment income (loss), net. We recognize realized gains and losses associated with our fair value method investments using the specific identification method. We classify the cash flows related to purchases of and proceeds from the sale of trading securities based on the nature of the securities and the purpose for which they were acquired.
	Equity Method
	We use the equity method to account for investments in which we have the ability to exercise significant influence over the investee's operating and financial policies or where we hold significant partnership or LLC interests. Equity method investments are recorded at cost and are adjusted to recognize (i) our proportionate share of the investee's net income or losses after the date of investment, (ii) amortization of the recorded investment that exceeds our share of the book value of the investee's net assets, (iii) additional contributions made and dividends received and (iv) impairments resulting from other-than-temporary declines in fair value. For some investments, we record our share of the investee's net income or loss one quarter in arrears due to the timing of our receipt of such information. Gains or losses on the sale of equity method investments are recorded to other income (expense), net. If an equity method investee were to issue additional securities that would change our proportionate share of the entity, we would recognize the change, if any, as a gain or loss in our consolidated statement of income.
	Cost Method
	We use the cost method to account for investments not accounted for under the fair value method or the equity method.
	Impairment Testing of Investments
	We review our investment portfolio each reporting period to determine whether there are identified events or circumstances that would indicate there is a decline in the fair value that would be considered other than temporary. For our nonpublic investments, if there are no identified events or circumstances that would have a significant adverse effect on the fair value of the investment, then the fair value is not estimated. If an investment is deemed to have experienced an other-than-temporary decline below its cost basis, we reduce the carrying amount of the investment to its quoted or estimated fair value, as applicable, and establish a new cost basis for the investment. For our AFS and cost method investments, we record the impairment to investment income (loss), net.
Property and Equipment	'
	Property and equipment are stated at cost. We capitalize improvements that extend asset lives and expense repairs and maintenance costs as incurred. We record depreciation using the straight-line method over the asset's estimated useful life. For assets that are sold or retired, we remove the applicable cost and accumulated depreciation and, unless the gain or loss on disposition is presented separately, we recognize it as a component of depreciation expense.
	We capitalize the costs associated with the construction of and improvements to our cable transmission and distribution facilities, costs associated with acquiring and deploying new customer premise equipment, and costs associated with installation of our services in accordance with accounting guidance related to cable television companies. Costs capitalized include all direct labor and materials, as well as various indirect costs. All costs incurred in connection with subsequent disconnects and reconnects are expensed as they are incurred.
	We evaluate the recoverability of our property and equipment whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of depreciation expense.
Goodwill and Intangible Assets	'
	We assess the recoverability of our goodwill annually, or more frequently whenever events or substantive changes in circumstances indicate that the carrying amount of a reporting unit may exceed its fair value. We test goodwill for impairment at the reporting unit level. To determine our reporting units, we evaluate the components one level below the segment level and we aggregate the components if they have similar economic characteristics. As a result of this assessment, our reporting units are the same as our five reportable segments. We evaluate the determination of our reporting units used to test for impairment periodically or whenever events or substantive changes in circumstances occur. The assessment of recoverability may first consider qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. The quantitative assessment considers if the carrying amount of a reporting unit exceeds its fair value, in which case an impairment charge is recorded to the extent the carrying amount of the reporting unit's goodwill exceeds its implied fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Indefinite-Lived Intangible Assets
	Indefinite-lived intangible assets consist primarily of our cable franchise rights, as well as trade names and FCC licenses. Our cable franchise rights represent the values we attributed to agreements with state and local authorities that allow access to homes and businesses in cable service areas acquired in business combinations. We do not amortize our cable franchise rights because we have determined that they meet the definition of indefinite-lived intangible assets since there are no legal, regulatory, contractual, competitive, economic or other factors which limit the period over which these rights will contribute to our cash flows. We reassess this determination periodically or whenever events or substantive changes in circumstances occur. Costs we incur in negotiating and renewing cable franchise agreements are included in other intangible assets and are generally amortized on a straight-line basis over the term of the franchise agreement.
	We assess the recoverability of our franchise rights and other indefinite-lived intangible assets annually, or more frequently whenever events or substantive changes in circumstances indicate that the assets might be impaired. Our three Cable Communications divisions represent the unit of account we use to test for impairment for our cable franchise rights. We evaluate the unit of account used to test for impairment of our cable franchise rights and other indefinite-lived intangible assets periodically or whenever events or substantive changes in circumstances occur to ensure impairment testing is performed at an appropriate level. The assessment of recoverability may first consider qualitative factors to determine whether it is more likely than not that the fair value of an indefinite-lived intangible asset is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. When performing a quantitative assessment, we estimate the fair value of our cable franchise rights and other indefinite-lived intangible assets primarily based on a discounted cash flow analysis that involves significant judgment. When analyzing the fair values indicated under the discounted cash flow models, we also consider multiples of operating income before depreciation and amortization generated by the underlying assets, current market transactions, and profitability information. If the fair value of our cable franchise rights or other indefinite-lived intangible assets were less than the carrying amount, we would recognize an impairment charge for the difference between the estimated fair value and the carrying value of the assets. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Finite-Lived Intangible Assets
	Finite-lived intangible assets are subject to amortization and consist primarily of customer relationships acquired in business combinations, cable franchise renewal costs, contractual operating rights, intellectual property rights and software. Our finite-lived intangible assets are amortized primarily on a straight-line basis over their estimated useful life or the term of the respective agreement.
	We capitalize direct development costs associated with internal-use software, including external direct costs of material and services and payroll costs for employees devoting time to these software projects. We also capitalize costs associated with the purchase of software licenses. We include these costs in other intangible assets and amortize them on a straight-line basis over a period not to exceed five years. We expense maintenance and training costs, as well as costs incurred during the preliminary stage of a project, as they are incurred. We capitalize initial operating system software costs and amortize them over the life of the associated hardware.
	We evaluate the recoverability of our intangible assets subject to amortization whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
Asset Retirement Obligations	'
	Asset Retirement Obligations
	Certain of our cable franchise agreements and lease agreements contain provisions requiring us to restore facilities or remove property in the event that the franchise or lease agreement is not renewed. We expect to continually renew our cable franchise agreements and therefore cannot reasonably estimate any liabilities associated with such agreements. A remote possibility exists that franchise agreements could be terminated unexpectedly, which could result in us incurring significant expense in complying with restoration or removal provisions. The disposal obligations related to our properties are not material to our consolidated financial statements. We do not have any significant liabilities related to asset retirements recorded in our consolidated financial statements.
Revenue Recognition	'
	Revenue Recognition
	Cable Communications Segment
	Our Cable Communications segment generates revenue primarily from subscriptions to our video, high-speed Internet and voice services (“cable services”) and from the sale of advertising. We recognize revenue from cable services as each service is provided. Customers are typically billed in advance on a monthly basis. We manage credit risk by screening applicants through the use of internal customer information, identification verification tools and credit bureau data. If a customer's account is delinquent, various measures are used to collect outstanding amounts, including termination of the customer's cable services. Since installation revenue obtained from the connection of customers to our cable systems is less than related direct selling costs, we recognize revenue as connections are completed.
	As part of our distribution agreements with cable networks, we generally receive an allocation of scheduled advertising time that we sell to local, regional and national advertisers. We recognize advertising revenue when the advertising is aired. In most cases, the available advertising time is sold by our sales force. In some cases, we work with representation firms as an extension of our sales force to sell a portion of the advertising time allocated to us. We also represent the advertising sales efforts of other multichannel video providers in some markets. Since we are acting as the principal in these arrangements, we report the advertising that is sold as revenue and the fees paid to representation firms and multichannel video providers as other operating and administrative expenses.
	Revenue earned from other sources is recognized when services are provided or events occur. Under the terms of our cable franchise agreements, we are generally required to pay to the franchising authority an amount based on our gross video revenue. We normally pass these fees through to our cable customers and classify the fees as a component of revenue with the corresponding costs included in other operating and administrative expenses.
	Cable Networks and Broadcast Television Segments
	Our Cable Networks segment generates revenue primarily from the distribution of our cable network programming to multichannel video providers, the sale of advertising and the licensing of our owned programming. Our Broadcast Television segment generates revenue primarily from the sale of advertising, the licensing of our owned programming and the fees received under retransmission consent agreements. We recognize revenue from distributors as programming is provided, generally under multiyear distribution agreements. From time to time, the distribution agreements expire while programming continues to be provided to the distributor based on interim arrangements while the parties negotiate new contract terms. Revenue recognition is generally limited to current payments being made by the distributor, typically under the prior contract terms, until a new contract is negotiated, sometimes with effective dates that affect prior periods. Differences between actual amounts determined upon resolution of negotiations and amounts recorded during these interim arrangements are recorded in the period of resolution.
	Advertising revenue for our Cable Networks and Broadcast Television segments is recognized in the period in which commercials are aired or viewed. In some instances, we guarantee viewer ratings for the commercials. To the extent there is a shortfall in the ratings that were guaranteed, a portion of the revenue is deferred until the shortfall is settled, primarily by providing additional advertising time. We record revenue from the licensing of our owned programming when the content is available for use by the licensee, and when certain other conditions are met. When license fees include advertising time, we recognize the advertising time component of revenue when the advertisements are aired or viewed.
	Filmed Entertainment Segment
	Our Filmed Entertainment segment generates revenue primarily from the worldwide distribution of our owned and acquired films for exhibition in movie theaters, the licensing of our owned and acquired films to cable, broadcast and premium networks and digital distributors, and the sale of our owned and acquired films on both standard-definition DVDs and Blu-ray discs (together, “DVDs”) and through digital distributors. We also generate revenue from producing and licensing live stage plays and distributing filmed entertainment produced by third parties. We recognize <>revenue from the distribution of films to movie theaters when the films are exhibited. We record revenue from the licensing of a film when the film is available for use by the licensee, and when certain other conditions are met. We recognize revenue from DVD sales, net of estimated returns and customer incentives, on the date that DVDs are delivered to and made available for sale by retailers.
	Theme Parks Segment
	Our Theme Parks segment generates revenue primarily from theme park attendance and per capita spending at our Universal theme parks in Orlando and Hollywood, as well as from licensing and other fees. We recognize <>revenue from advance theme park ticket sales when the tickets are used. For annual passes, we recognize revenue on a straight-line basis over the annual period following the initial redemption date.
Cable Communications Programming Expenses	'
	Cable Communications Programming Expenses
	Cable Communications programming expenses are the fees we pay to license the programming we distribute to our video customers. Programming is acquired for distribution to our video customers, generally under multiyear distribution agreements, with rates typically based on the number of customers that receive the programming, adjusted for channel positioning and the extent of distribution. From time to time these contracts expire and programming continues to be provided under interim arrangements while the parties negotiate new contractual terms, sometimes with effective dates that affect prior periods. While payments are typically made under the prior contract's terms, the amount of programming expenses recorded during these interim arrangements is based on our estimates of the ultimate contractual terms expected to be negotiated. Differences between actual amounts determined upon resolution of negotiations and amounts recorded during these interim arrangements are recorded in the period of resolution.
	When our Cable Communications segment receives incentives from cable networks for the licensing of their programming, we defer a portion of these incentives, which are included in other current and noncurrent liabilities, and recognize them over the term of the contract as a reduction to programming and production expenses.
Advertising Expenses	'
	Advertising Expenses
	Advertising costs are expensed as incurred.
Share-Based Compensation	'
	Our share-based compensation primarily consists of awards of stock options and RSUs to certain employees and directors as part of our approach to long-term incentive compensation. Awards generally vest over a period of 5 years and in the case of stock options, have a 10 year term. Additionally, through our employee stock purchase plans, employees are able to purchase shares of Comcast Class A common stock at a discount through payroll deductions.
	The cost associated with our share-based compensation is based on an award's estimated fair value at the date of grant and is recognized over the period in which any related services are provided. We use the Black-Scholes option pricing model to estimate the fair value of stock option awards. RSUs are valued based on the closing price of our Class A common stock on the date of grant and are discounted for the lack of dividends, if any, during the vesting period. The table below presents the weighted-average fair value on the date of grant of RSUs and Class A common stock options awarded under our various plans and the related weighted-average valuation assumptions.
Postretirement and Pension Benefits	'
	All of our postretirement benefit plans are unfunded and substantially all of our postretirement benefit obligations are recorded to noncurrent liabilities. The expense we recognize related to our postretirement benefit plans is determined using certain assumptions, including the discount rate.
	NBCUniversal
	NBCUniversal sponsors various domestic qualified and nonqualified defined benefit plans for which future benefits were frozen effective December 31, 2012. We ceased to recognize service costs associated with these defined benefit plans following the date on which future benefits were frozen. The expense we recognize related to our defined benefit plans is determined using certain assumptions, including the discount rate and the expected long-term rate of return on plan assets. We recognize the funded or unfunded status of our defined benefit plans as an asset or liability in our consolidated balance sheet and recognize changes in the funded status in the year in which the changes occur through accumulated other comprehensive income (loss). In the event of a defined benefit plan termination, we expect to fully fund and settle the plan within 180 days of approval by the Internal Revenue Service (“IRS”) and the Pension Benefit Guaranty Corporation (“PBGC”).
Income Taxes	'
	We base our provision for income taxes on our current period income, changes in our deferred income tax assets and liabilities, income tax rates, changes in estimates of our uncertain tax positions, and tax planning opportunities available in the jurisdictions in which we operate. We recognize deferred tax assets and liabilities when there are temporary differences between the financial reporting basis and tax basis of our assets and liabilities and for the expected benefits of using net operating loss carryforwards. When a change in the tax rate or tax law has an impact on deferred taxes, we apply the change based on the years in which the temporary differences are expected to reverse. We record the change in our consolidated financial statements in the period of enactment.
	Income tax consequences that arise in connection with a business combination include identifying the tax basis of assets and liabilities acquired and any contingencies associated with uncertain tax positions assumed or resulting from the business combination. Deferred tax assets and liabilities related to temporary differences of an acquired entity are recorded as of the date of the business combination and are based on our estimate of the ultimate tax basis that will be accepted by the various taxing authorities. We record liabilities for contingencies associated with prior tax returns filed by the acquired entity based on criteria set forth in the appropriate accounting guidance. We adjust the deferred tax accounts and the liabilities periodically to reflect any revised estimated tax basis and any estimated settlements with the various taxing authorities. The effects of these adjustments are recorded to income tax expense.
	From time to time, we engage in transactions in which the tax consequences may be subject to uncertainty. In these cases, we evaluate our tax positions using the recognition threshold and the measurement attribute in accordance with the accounting guidance related to uncertain tax positions. Examples of these transactions include business acquisitions and dispositions, including consideration paid or received in connection with these transactions, and certain financing transactions. Significant judgment is required in assessing and estimating the tax consequences of these transactions. We determine whether it is more likely than not that a tax position will be sustained on examination, including the resolution of any related appeals or litigation processes, based on the technical merits of the position. A tax position that meets the more-likely-than-not recognition threshold is measured to determine the amount of benefit to be recognized in our financial statements. We classify interest and penalties, if any, associated with our uncertain tax positions as a component of income tax expense.
Derivative Financial Instruments	'
	Derivative Financial Instruments
	We use derivative financial instruments to manage our exposure to the risks associated with fluctuations in interest rates, foreign exchange rates and equity prices. Our objective is to manage the financial and operational exposure arising from these risks by offsetting gains and losses on the underlying exposures with gains and losses on the derivatives used to economically hedge them.
	Our derivative financial instruments are recorded on our consolidated balance sheet at fair value. See Note 6 for additional information on the derivative component of our prepaid forward sale agreements. The impact of our other derivative financial instruments on our consolidated financial statements was not material for all periods presented.
	The derivative component of the prepaid forward sale agreements are equity derivative financial instruments embedded in the related contracts, which we use to manage our exposure to and benefits from price fluctuations in the common stock of the related investments. For these derivative financial instruments, we separate the derivative component from the host contract and record the change in its value each period to investment income (loss), net.
Receivables Monetization	'
	Prior to the terminations, we accounted for receivables monetized through these programs as sales in accordance with the appropriate accounting guidance. We received deferred consideration from the assets sold in the form of a receivable, which was funded by residual cash flows after the senior interests had been fully paid. As of December 31, 2012, the deferred consideration was included in receivables, net at its initial fair value, which reflects the net cash flows we expected to receive related to those interests.
NBCUniversal Media, LLC [Member]	'
Basis of Presentation	'
	The accompanying consolidated financial statements include all entities in which we have a controlling voting interest (“subsidiaries”) and variable interest entities (“VIEs”) required to be consolidated in accordance with generally accepted accounting principles in the United States (“GAAP”). Transactions between NBCUniversal and Comcast, and their consolidated subsidiaries are reflected in these consolidated financial statements and disclosed as related party transactions when material.
Foreign Currency Translation	'
	We translate assets and liabilities of our foreign subsidiaries where the functional currency is the local currency, primarily the euro and the British pound, into U.S. dollars at the exchange rate in effect as of the balance sheet date. The related translation adjustments are recorded as a component of accumulated other comprehensive income (loss). We translate revenue and expenses using average monthly exchange rates, and the related foreign currency transaction gains and losses are included in our consolidated statement of income.
Cash Equivalents	'
	Cash Equivalents
	The carrying amounts of our cash equivalents approximate their fair value. Our cash equivalents consist primarily of money market funds and U.S. government obligations, as well as commercial paper and certificates of deposit with maturities of less than three months when purchased.
Film And Television Costs	'
	Capitalization of Film and Television Costs
	We capitalize film and television production costs, including direct costs, production overhead, print costs, development costs and interest. We amortize capitalized film and television production costs, including acquired libraries, and accrue costs associated with participation and residual payments to programming and production expense. We generally record the amortization and the accrued costs using the individual film forecast computation method, which amortizes such costs in the same ratio as the associated ultimate revenue. Estimates of total revenue and total costs are based on anticipated release patterns, public acceptance and historical results for similar productions. Unamortized film and television costs, including acquired film and television libraries, are stated at the lower of unamortized cost or fair value. We do not capitalize costs related to the distribution of a film to movie theaters or the licensing or sale of a film or television production, which are primarily costs associated with the marketing and distribution of film and television programming.
	In determining the estimated lives and method of amortization of acquired film and television libraries, we generally use the method and the life that most closely follow the undiscounted cash flows over the estimated life of the asset.
	Upon the occurrence of an event or a change in circumstance that was known or knowable as of the balance sheet date and that indicates the fair value of a film is less than its unamortized costs, we determine the fair value of the film and record an impairment charge for the amount by which the unamortized capitalized costs exceed the film's fair value.
	We enter into arrangements with third parties to jointly finance and distribute certain of our film productions. These arrangements, which are referred to as cofinancing arrangements, can take various forms. In most cases, the arrangement involves the grant of an economic interest in a film to a third-party investor. The number of investors and the terms of these arrangements can vary, although in most cases an investor assumes full risk for the portion of the film acquired in these arrangements. We account for the proceeds received from a third-party investor under these arrangements as a reduction to our capitalized film costs. In these arrangements, the investor owns an undivided copyright interest in the film and, therefore, in each period we record either a charge or a benefit to programming and production expense to reflect the estimate of the third-party investor's interest in the profit or loss of the film. The estimate of the third-party investor's interest in the profit or loss of a film is determined using the ratio of actual revenue earned to date to the ultimate revenue expected to be recognized over the film's useful life.
	We capitalize the costs of programming content that we license but do not own, including rights to multiyear live-event sports programming, at the earlier of when payments are made for the programming or when the license period begins and the content is available for use. We amortize capitalized programming costs as the associated programs are broadcast. We amortize multiyear, live-event sports programming rights using the ratio of the current period revenue to the estimated total remaining revenue or under the terms of the contract.
	Acquired programming costs are recorded at the lower of unamortized cost or net realizable value on a program by program, package, channel or daypart basis. A daypart is an aggregation of programs broadcast during a particular time of day or programs of a similar type. Acquired programming used in our Cable Networks segment is primarily tested on a channel basis for impairment, whereas acquired programming used in our Broadcast Television segment is tested on a daypart basis. If we determine that the estimates of future cash flows are insufficient or if there is no plan to broadcast certain programming, we recognize an impairment charge to programming and production expense.
Investments	'
	Equity Method
	We use the equity method to account for investments in which we have the ability to exercise significant influence over the investee's operating and financial policies or where we hold significant partnership or LLC interests. Equity method investments are recorded at cost and are adjusted to recognize (i) our proportionate share of the investee's net income or losses after the date of investment, (ii) amortization of the recorded investment that exceeds our share of the book value of the investee's net assets, (iii) additional contributions made and dividends received, and (iv) impairments resulting from other-than-temporary declines in fair value. Gains or losses on the sale of equity method investments are recorded to other income (expense), net. If an equity method investee were to issue additional securities that would change our proportionate share of the entity, we would recognize the change, if any, as a gain or loss in our consolidated statement of income.
	Impairment Testing of Investments
	We review our investment portfolio each reporting period to determine whether there are identified events or circumstances that would indicate there is a decline in the fair value that would be considered other than temporary. For our nonpublic investments, if there are no identified events or circumstances that would have a significant adverse effect on the fair value of the investment, then the fair value is not estimated. If an investment is deemed to have experienced an other-than-temporary decline below its cost basis, we reduce the carrying amount of the investment to its quoted or estimated fair value, as applicable, and establish a new cost basis for the investment. For our AFS and cost method investments, we record the impairment to investment income (loss), net. For our equity method investments, we record the impairment to other income (expense), net.
Property and Equipment	'
	Property and equipment are stated at cost. We capitalize improvements that extend asset lives and expense repairs and maintenance costs as incurred. We record depreciation using the straight-line method over the asset's estimated useful life. For assets that are sold or retired, we remove the applicable cost and accumulated depreciation and, unless the gain or loss on disposition is presented separately, we recognize it as a component of depreciation expense.
	We evaluate the recoverability of our property and equipment whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of depreciation expense.
Goodwill and Intangible Assets	'
	We assess the recoverability of our goodwill annually, or more frequently whenever events or substantive changes in circumstances indicate that the carrying amount of a reporting unit may exceed its fair value. We test goodwill for impairment at the reporting unit level. To determine our reporting units, we evaluate the components one level below the segment level and we aggregate the components if they have similar economic characteristics. As a result of this assessment, our reporting units are the same as our four reportable segments. We evaluate the determination of our reporting units used to test for impairment periodically or whenever events or substantive changes in circumstances occur. The assessment of recoverability may first consider qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. The quantitative assessment considers if the carrying amount of a reporting unit exceeds its fair value, in which case an impairment charge is recorded to the extent the carrying amount of the reporting unit's goodwill exceeds its implied fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Indefinite-Lived Intangible Assets
	Indefinite-lived intangible assets consist of trade names and FCC licenses. We assess the recoverability of our indefinite-lived intangible assets annually, or more frequently whenever events or substantive changes in circumstances indicate that the assets might be impaired. We evaluate the unit of account used to test for impairment of our indefinite-lived intangible assets periodically or whenever events or substantive changes in circumstances occur to ensure impairment testing is performed at an appropriate level. The assessment of recoverability may first consider qualitative factors to determine whether it is more likely than not that the fair value of an indefinite-lived intangible asset is less than its carrying amount. A quantitative assessment is performed if the qualitative assessment results in a more-likely-than-not determination or if a qualitative assessment is not performed. When performing a quantitative assessment, we estimate the fair value of our indefinite-lived intangible assets primarily based on a discounted cash flow analysis that involves significant judgment. When analyzing the fair values indicated under the discounted cash flow models, we also consider multiples of operating income before depreciation and amortization generated by the underlying assets, current market transactions, and profitability information. If the fair value of our indefinite-lived intangible assets were less than the carrying amount, we would recognize an impairment charge for the difference between the estimated fair value and the carrying value of the assets. Unless presented separately, the impairment charge is included as a component of amortization expense.
	Finite-Lived Intangible Assets
	Finite-lived intangible assets are subject to amortization and consist primarily of customer relationships acquired in business combinations, intellectual property rights and software. Our finite-lived intangible assets are amortized primarily on a straight-line basis over their estimated useful life or the term of the respective agreement.
	We capitalize direct development costs associated with internal-use software, including external direct costs of material and services and payroll costs for employees devoting time to these software projects. We also capitalize costs associated with the purchase of software licenses. We include these costs in intangible assets and amortize them on a straight-line basis over a period not to exceed five years. We expense maintenance and training costs, as well as costs incurred during the preliminary stage of a project, as they are incurred. We capitalize initial operating system software costs and amortize them over the life of the associated hardware.
	We evaluate the recoverability of our intangible assets subject to amortization whenever events or substantive changes in circumstances indicate that the carrying amount may not be recoverable. The evaluation is based on the cash flows generated by the underlying asset groups, including estimated future operating results, trends or other determinants of fair value. If the total of the expected future undiscounted cash flows were less than the carrying amount of the asset group, we would recognize an impairment charge to the extent the carrying amount of the asset group exceeded its estimated fair value. Unless presented separately, the impairment charge is included as a component of amortization expense.
Revenue Recognition	'
	Revenue Recognition
	Cable Networks and Broadcast Television Segments
	Our Cable Networks segment generates revenue primarily from the distribution of our cable network programming to multichannel video providers, the sale of advertising and the licensing of our owned programming. Our Broadcast Television segment generates revenue primarily from the sale of advertising, the licensing of our owned programming and the fees received under retransmission consent agreements. We recognize revenue from distributors as programming is provided, generally under multiyear distribution agreements. From time to time, the distribution agreements expire while programming continues to be provided to the distributor based on interim arrangements while the parties negotiate new contract terms. Revenue recognition is generally limited to current payments being made by the distributor, typically under the prior contract terms, until a new contract is negotiated, sometimes with effective dates that affect prior periods. Differences between actual amounts determined upon resolution of negotiations and amounts recorded during these interim arrangements are recorded in the period of resolution.
	Advertising revenue for our Cable Networks and Broadcast Television segments is recognized in the period in which commercials are aired or viewed. In some instances, we guarantee viewer ratings for the commercials. To the extent there is a shortfall in the ratings that were guaranteed, a portion of the revenue is deferred until the shortfall is settled, primarily by providing additional advertising time. We record revenue from the licensing of our owned programming when the content is available for use by the licensee, and when certain other conditions are met. When license fees include advertising time, we recognize the advertising time component of revenue when the advertisements are aired or viewed.
	Filmed Entertainment Segment
	Our Filmed Entertainment segment generates revenue primarily from the worldwide distribution of our owned and acquired films for exhibition in movie theaters, the licensing of our owned and acquired films to cable, broadcast and premium networks and digital distributors, and the sale of our owned and acquired films on both standard-definition DVDs and Blu-ray discs (together, “DVDs”) and through digital distributors. We also generate revenue from producing and licensing live stage plays and distributing filmed entertainment produced by third parties. We recognize <>revenue from the distribution of films to movie theaters when the films are exhibited. We record revenue from the licensing of a film when the film is available for use by the licensee, and when certain other conditions are met. We recognize revenue from DVD sales, net of estimated returns and customer incentives, on the date that DVDs are delivered to and made available for sale by retailers.
	Theme Parks Segment
	Our Theme Parks segment generates revenue primarily from theme park attendance and per capita spending at our Universal theme parks in Orlando and Hollywood, as well as from licensing and other fees. We recognize <>revenue from advance theme park ticket sales when the tickets are used. For annual passes, we recognize revenue on a straight-line basis over the annual period following the initial redemption date.
Advertising Expenses	'
	Advertising Expenses
	Advertising costs are expensed as incurred.
Share-Based Compensation	'
	Comcast maintains share-based compensation plans that primarily consist of awards of stock options and RSUs to certain employees and directors as part of its approach to long-term incentive compensation. Awards generally vest over a period of 5 years and in the case of stock options, have a 10 year term. Additionally, through the employee stock purchase plans, employees are able to purchase shares of Comcast Class A common stock at a discount through payroll deductions. Certain of our employees participate in these plans and the expense associated with their participation is settled in cash with Comcast.
	The cost associated with Comcast's share-based compensation is based on an award's estimated fair value at the date of grant and is recognized over the period in which any related services are provided. Comcast uses the Black-Scholes option pricing model to estimate the fair value of stock option awards. RSUs are valued based on the closing price of Comcast Class A common stock on the date of grant and are discounted for the lack of dividends, if any, during the vesting period.
Postretirement and Pension Benefits	'
	All of our postretirement benefit plans are unfunded and substantially all of our postretirement benefit obligations are recorded to noncurrent liabilities. The expense we recognize related to our postretirement benefit plans is determined using certain assumptions, including the discount rate.
	Pension Plans
	We sponsor various domestic qualified and nonqualified defined benefit plans for which future benefits were frozen effective December 31, 2012. We ceased to recognize service costs associated with these defined benefit plans following the date on which future benefits were frozen. The expense we recognize related to our defined benefit plans is determined using certain assumptions, including the discount rate and the expected long-term rate of return on plan assets. We recognize the funded or unfunded status of our defined benefit plans as an asset or liability in our consolidated balance sheet and recognize changes in the funded status in the year in which the changes occur through accumulated other comprehensive income (loss). In the event of a defined benefit plan termination, we expect to fully fund and settle the plan within 180 days of approval by the Internal Revenue Service (“IRS”) and the Pension Benefit Guaranty Corporation (“PBGC”). In addition to the defined benefit plans we sponsor, we are also obligated to reimburse GE for future benefit payments to those participants who were vested in the supplemental pension plan sponsored by GE at the time of the close of the Joint Venture transaction.
Derivative Financial Instruments	'
	Derivative Financial Instruments
	We use derivative financial instruments to manage our exposure to the risks associated with fluctuations in foreign exchange rates and interest rates. Our objective is to manage the financial and operational exposure arising from these risks by offsetting gains and losses on the underlying exposures with gains and losses on the derivatives used to economically hedge them.
	Our derivative financial instruments are recorded on our consolidated balance sheet at fair value.
Receivables Monetization	'
	Prior to the terminations, we accounted for receivables monetized through these programs as sales in accordance with the appropriate accounting guidance. We received deferred consideration from the assets sold in the form of a receivable, which was funded by residual cash flows after the senior interests had been fully paid. As of December 31, 2012, the deferred consideration was included in receivables, net at its initial fair value, which reflects the net cash flows we expected to receive related to those interests.

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2013
Computation of diluted EPS	'
	Computation of Diluted EPS
			2013					2012					2011
	Year ended December 31 (in millions, except per share data)		Net Income Attributable to Comcast Corporation	Shares		Per Share Amount		Net Income Attributable to Comcast Corporation	Shares		Per Share Amount		Net Income Attributable to Comcast Corporation	Shares		Per Share Amount
	Basic EPS attributable to Comcast Corporation shareholders	$	6,816	2,625	$	2.6	$	6,203	2,678	$	2.32	$	4,160	2,746	$	1.51
	Effect of dilutive securities:
	Assumed exercise or issuance of shares relating to stock plans			40					39					32
	Diluted EPS attributable to Comcast Corporation shareholders	$	6,816	2,665	$	2.56	$	6,203	2,717	$	2.28	$	4,160	2,778	$	1.5

Related_Party_Transactions_Tab

Related Party Transactions (Tables) (NBCUniversal Media, LLC [Member])	12 Months Ended
	Dec. 31, 2013
NBCUniversal Media, LLC [Member]	'
Related Party Transactions Condensed Financial Statements	'
	Consolidated Balance Sheet
					Successor
	December 31 (in millions)			2013			2012
	Transactions with Comcast and consolidated subsidiaries
		Receivables, net		$	228		$	204
		Accounts payable and accrued expenses related to trade creditors		$	56		$	25
		Accrued expenses and other current liabilities		$	37		$	1
		Note payable to Comcast		$	799		$	-
		Other noncurrent liabilities		$	383		$	-
	Consolidated Statement of Income
				Successor
	(in millions)			Year Ended December 31, 2013		Year Ended December 31, 2012		For the Period January 29, 2011 to December 31, 2011
	Transactions with Comcast and consolidated subsidiaries
		Revenue	$	1,262	$	1,228	$	1,025
		Operating costs and expenses	$	-190	$	-175	$	-72

Film_and_Television_Costs_Tabl

Film and Television Costs (Tables)	12 Months Ended
	Dec. 31, 2013
Film and Television Costs	'
	December 31 (in millions)			2013		2012
	Film Costs:
		Released, less amortization	$	1,630	$	1,472
		Completed, not released		70		99
		In production and in development		658		1,048
				2,358		2,619
	Television Costs:
		Released, less amortization		1,155		1,124
		In production and in development		370		334
				1,525		1,458
	Programming rights, less amortization			2,039		1,886
				5,922		5,963
	Less: Current portion of programming rights			928		909
	Film and television costs		$	4,994	$	5,054
NBCUniversal Media, LLC [Member]	'
Film and Television Costs	'
				Successor
	December 31 (in millions)			2013		2012
	Film Costs:
		Released, less amortization	$	1,630	$	1,472
		Completed, not released		70		99
		In production and in development		658		1,048
				2,358		2,619
	Television Costs:
		Released, less amortization		1,155		1,124
		In production and in development		370		334
				1,525		1,458
	Programming rights, less amortization			2,003		1,808
				5,886		5,885
	Less: Current portion of programming rights			903		844
	Film and television costs		$	4,983	$	5,041

Investments_Tables

Investments (Tables)	12 Months Ended
	Dec. 31, 2013
Investment Summary	'
	December 31 (in millions)			2013		2012
	Fair Value Method		$	4,345	$	4,493
	Equity Method:
		The Weather Channel		333		471
		Hulu		187		-
		Other		469		693
				989		1,164
	Cost Method:
		AirTouch		1,553		1,538
		Other		456		594
				2,009		2,132
	Total investments			7,343		7,789
	Less: Current investments			3,573		1,464
	Noncurrent investments		$	3,770	$	6,325
Investment Income (Loss), Net	'
	Investment Income (Loss), Net
	Year ended December 31 (in millions)			2013		2012		2011
	Gains on sales and exchanges of investments, net		$	484	$	30	$	41
	Investment impairment losses			-29		-24		-5
	Unrealized gains (losses) on securities underlying prepaid forward sale agreements			1,601		1,159		192
	Mark to market adjustments on derivative component of prepaid forward sale
		agreements and indexed debt instruments		-1,604		-1,071		-119
	Interest and dividend income			111		119		110
	Other, net			13		6		-60
	Investment income (loss), net		$	576	$	219	$	159
Prepaid Forward Sale Agreements	'
	Prepaid Forward Sale Agreements
	December 31 (in millions)			2013		2012
	Assets:
		Fair value equity securities held as collateral	$	3,959	$	4,143
	Liabilities:
		Obligations under prepaid forward sale agreements	$	811	$	1,248
		Derivative component of prepaid forward sale agreements		2,800		2,302
	Total liabilities		$	3,611	$	3,550
NBCUniversal Media, LLC [Member]	'
Investment Summary	'
				Successor
	December 31 (in millions)			2013		2012
	Fair Value Method		$	11	$	21
	Equity Method:
		The Weather Channel		333		471
		Hulu		187		-
		Other		332		545
				852		1,016
	Cost Method			21		229
	Total investments		$	884	$	1,266

Property_and_Equipment_Tables

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2013
Property and Equipment	'
	December 31 (in millions)	Weighted-Average Original Useful Life As of December 31, 2013			2013		2012
	Cable distribution system	11	years	$	30,498	$	29,528
	Customer premise equipment	6	years		25,949		24,763
	Other equipment	5	years		6,826		5,909
	Buildings and leasehold improvements	21	years		8,057		5,468
	Land		-		1,084		989
	Property and equipment, at cost				72,414		66,657
	Less: Accumulated depreciation				42,574		39,425
	Property and equipment, net			$	29,840	$	27,232
NBCUniversal Media, LLC [Member]	'
Property and Equipment	'
					Successor
	December 31 (in millions)	Weighted-Average Original Useful Life As of December 31, 2013			2013		2012
	Buildings and leasehold improvements	20	years	$	5,239	$	3,223
	Furniture, fixtures and equipment	6	years		2,383		1,961
	Construction in process		-		828		552
	Land		-		799		728
	Property and equipment, at cost				9,249		6,464
	Less: Accumulated depreciation				1,599		1,083
	Property and equipment, net			$	7,650	$	5,381

Goodwill_Tables

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2013
Schedule of Goodwill	'
	Goodwill
					NBCUniversal
	(in millions)			Cable Communications		Cable Networks		Broadcast Television		Filmed Entertainment		Theme Parks		Corporate and Other		Total
	Balance, December 31, 2011		$	12,208	$	12,744	$	772	$	1	$	1,140	$	9	$	26,874
	Acquisitions:
		MSNBC.com		-		227		-		-		-		-		227
		Other		-		79		-		-		-		-		79
	Dispositions			-1		-		-		-		-		-		-1
	Adjustments(a)			-1		-24		-11		-		-158		-		-194
	Balance, December 31, 2012			12,206		13,026		761		1		982		9		26,985
	Acquisitions			-		39		3		-		-		-		42
	Adjustments(a)			-		65		5		-		-		1		71
	Balance, December 31, 2013		$	12,206	$	13,130	$	769	$	1	$	982	$	10	$	27,098
Other Intangible Assets	'
	Intangible Assets
						2013				2012
	December 31 (in millions)		Weighted-Average Original Useful Life as of December 31, 2013			Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
	Indefinite-Lived Intangible Assets:
		Franchise rights		N/A	$	59,364			$	59,364
		Trade names		N/A		3,089				3,080
		FCC licenses		N/A		652				636
	Finite-Lived Intangible Assets:
		Customer relationships	19	years		15,037	$	-4,772		14,970	$	-3,971
		Cable franchise renewal costs and contractual operating rights	10	years		1,360		-745		1,257		-676
		Software	5	years		4,271		-2,405		3,795		-2,123
		Patents and other technology rights	9	years		361		-307		350		-283
		Other agreements and rights	20	years		1,433		-645		1,414		-609
	Total				$	85,567	$	-8,874	$	84,866	$	-7,662
Amortization of Intangible Assets	'
	Estimated Amortization Expense of Finite-Lived Intangibles
	(in millions)
	2014	$	1,487
	2015	$	1,345
	2016	$	1,196
	2017	$	1,046
	2018	$	893
NBCUniversal Media, LLC [Member]	'
Schedule of Goodwill	'
	Goodwill
	Successor (in millions)			Cable Networks		Broadcast Television		Filmed Entertainment		Theme Parks		Total
	Balance, December 31, 2011		$	12,744	$	772	$	1	$	1,140	$	14,657
	Acquisitions:
		MSNBC.com		227		-		-		-		227
		Other		79		-		-		-		79
	Adjustments(a)			-24		-11		-		-158		-193
	Balance, December 31, 2012			13,026		761		1		982		14,770
	Acquisitions			39		3		-		-		42
	Adjustments(a)			65		5		-		-		70
	Balance, December 31, 2013		$	13,130	$	769	$	1	$	982	$	14,882
Other Intangible Assets	'
	Intangible Assets
						Successor
						2013				2012
	December 31 (in millions)		Weighted-Average Original Useful Life as of December 31, 2013			Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
	Finite-Lived Intangible Assets:
		Customer relationships	19 years		$	13,086	$	-2,982	$	13,026	$	-2,328
		Software	5 years			522		-240		409		-164
		Other	21 years			1,511		-781		1,507		-746
	Indefinite-Lived Intangible Assets:
		Trade names				3,089				3,080
		FCC licenses				652				636
	Total				$	18,860	$	-4,003	$	18,658	$	-3,238
Amortization of Intangible Assets	'
	Estimated Amortization Expense of Finite-Lived Intangibles
	(in millions)
	2014	$	771
	2015	$	762
	2016	$	739
	2017	$	740
	2018	$	734

LongTerm_Debt_Tables

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2013
Schedule of Long-Term Debt	'
	Long-Term Debt Outstanding
	December 31 (in millions)	Weighted-Average Interest Rate as of December 31, 2013			2013		2012
	Commercial paper	0.295	%	$	1,350	$	-
	Revolving bank credit facilities	1.166	%		1,250		-
	Senior notes with maturities of 5 years or less	4.718	%		15,080		12,991
	Senior notes with maturities between 6 and 10 years	4.558	%		11,533		10,334
	Senior notes with maturities greater than 10 years(a)	5.971	%		18,010		16,801
	Other, including capital lease obligations	—			624		332
	Total debt	4.8	%(b)		47,847		40,458
	Less: Current portion				3,280		2,376
	Long-term debt			$	44,567	$	38,082
	(a) Both the December 31, 2013 and 2012 amounts include £625 million of 5.50% notes due 2029 translated at $1 billion, using the exchange rates as of these dates.
	(b) Includes the effects of our derivative financial instruments.
Debt Maturities	'
	Debt Maturities
	(in millions)	Weighted-Average Interest Rate
	2014	2.343	%		$	3,280
	2015	5.899	%		$	3,420
	2016	4.265	%		$	3,501
	2017	6.977	%		$	2,557
	2018	4.51	%		$	5,394
	Thereafter	5.451	%		$	29,695
Debt Borrowings	'
	2013 Debt Borrowings
	Year ended December 31, 2013 (in millions)
	Comcast 4.250% senior notes due 2033	$	1,700
	Comcast 2.850% senior notes due 2023		750
	Comcast 4.500% senior notes due 2043		500
	Total	$	2,950
Debt Repayments and Repurchases	'
	2013 Debt Repayments and Redemptions
	Year ended December 31, 2013 (in millions)
	Comcast 8.375% senior notes due 2013	$	1,714
	Comcast 7.125% senior notes due 2013		383
	Comcast 7.875% senior notes due 2013		238
	Other		109
	Total	$	2,444
NBCUniversal Media, LLC [Member]	'
Schedule of Long-Term Debt	'
	Long-Term Debt Outstanding
		Weighted-Average Interest Rate as of December 31, 2013		Successor
	December 31 (in millions)				2013			2012
	Senior notes with maturities of 5 years or less	2.884	%		2,917		2,933
	Senior notes with maturities between 6 and 10 years	4.388	%		4,996		3,999
	Senior notes with maturities greater than 10 years	5.614	%		3,205		4,203
	Other, including capital lease obligations	—			47		106
	Total debt	4.22	%(a)		11,165		11,241
	Less: Current portion				906		10
	Long-term debt			$	10,259		11,231
	(a) Includes the effects of our derivative financial instruments.
Debt Maturities	'
	Debt Maturities
	(in millions)	Weighted-Average Interest Rate
	2014	2.121	%		$	906
	2015	3.597	%		$	1,032
	2016	2.876	%		$	1,008
	2017	6.287	%		$	2
	2018	6.299	%		$	2
	Thereafter	4.871	%		$	8,215

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2013
Fair Value Assets and Liabilities Measured on Recurring Basis	'
	Recurring Fair Value Measures
			Fair Value as of December 31, 2013								Fair Value as of December 31, 2012
	(in millions)		Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
	Assets
	Trading securities	$	3,956	$	-	$	-	$	3,956	$	4,027	$	-	$	-	$	4,027
	Available-for-sale securities		260		118		11		389		367		76		21		464
	Interest rate swap agreements		-		110		-		110		-		210		-		210
	Other		-		80		1		81		-		36		2		38
	Total	$	4,216	$	308	$	12	$	4,536	$	4,394	$	322	$	23	$	4,739
	Liabilities
	Derivative component of prepaid forward sale agreements and indexed debt instruments	$	-	$	2,816	$	-	$	2,816	$	-	$	2,305	$	-	$	2,305
	Contractual obligations				-		747		747		-		-		1,055		1,055
	Contingent consideration		-		-		684		684		-		-		587		587
	Other		-		16		-		16		-		14		-		14
	Total	$	-	$	2,832	$	1,431	$	4,263	$	-	$	2,319	$	1,642	$	3,961
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	'
	Changes in Contractual Obligations and Contingent Consideration
	(in millions)		Contractual Obligations		Contingent Consideration
	Balance, December 31, 2012	$	1,055	$	587
	Fair value adjustments		158		106
	Payments		-83		-214
	Redemption Transaction (see Note 4 for additional information)		-		205
	Liberty Media transaction (see Note 6 for additional information)		-383		-
	Balance, December 31, 2013	$	747	$	684
NBCUniversal Media, LLC [Member]	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	'
	Changes in Contractual Obligations
	Successor (in millions)
	Balance, December 31, 2012	$	1,055
	Fair value adjustments		158
	Payments		-83
	Liberty Media transaction		-383
	Balance, December 31, 2013	$	747

Noncontrolling_Interests_Table

Noncontrolling Interests (Tables)	12 Months Ended
	Dec. 31, 2013
Schedule Summarizing Changes in Equity Resulting from Net Income Attributable to Parent and Transfers to or from Noncontrolling Interests	'
	Changes in Equity
	Year ended December 31 (in millions)			2013
	Net income attributable to Comcast Corporation		$	6,816
	Transfers from (to) noncontrolling interests:
		Decrease in Comcast Corporation additional paid-in capital resulting from the
		purchase of GE’s redeemable noncontrolling common equity interest		-1,651
		Other		-26
	Changes in equity resulting from net income attributable to Comcast Corporation and
		transfers from (to) noncontrolling interests	$	5,139

Postretirement_Pension_and_Oth

Postretirement, Pension and Other Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Postretirement And Pension Benefits	'
				2013					2012						2011
	Year ended December 31 (in millions)			Postretirement Benefits		Pension Benefits			Postretirement Benefits			Pension Benefits			Postretirement Benefits			Pension Benefits
	Benefit obligation		$	633		$	498		$	703		$	805		$	618		$	638
	Fair value of plan assets(a)			-			220			-			403			-			176
	Plan funded status and recorded
		benefit obligation		-633			-278			-703			-402			-618			-462
	Portion of benefit obligation not
		yet recognized in benefits expense		-110			-3			17			151			-17			137
	Benefits expense(b)			65			12			60			163			47			117
	Discount rate			5.00-5.25	%	4.50-5.25		%		4.25	%	3.25-4.25		%		4.75	%	4.75-5.25		%
	Expected return on plan assets			N/A			5	%		N/A			5	%		N/A			6.5	%
Deferred Compensation Plans	'
	Year ended December 31 (in millions)		2013		2012		2011
	Benefit obligation	$	1,434	$	1,247	$	1,059
	Interest expense	$	128	$	107	$	99
Benefit Obligation and Expense for Our Split-Dollar Life Insurance Agreements	'
	Year ended December 31 (in millions)		2013		2012		2011
	Benefit obligation	$	212	$	202	$	169
	Other operating and administrative expenses	$	50	$	58	$	27
NBCUniversal Media, LLC [Member]	'
Postretirement And Pension Benefits	'
			Successor
			Year Ended December 31,						Year Ended December 31,						For the Period January 29, 2011 to December 31,
			2013						2012						2011
	(in millions)		Postretirement Benefits			Pension Benefits			Postretirement Benefits			Pension Benefits			Postretirement Benefits			Pension Benefits
	Benefit obligation		$	158		$	498		$	177		$	546		$	161		$	427
	Fair value of plan assets(a)			-			220			-			217			-			-
	Plan funded status and recorded
		benefit obligation		-158			-278			-177			-329			-161			-427
	Portion of benefit obligation not yet
		recognized in benefit expense		-44			-3			-11			53			-13			71
	Benefits expense(b)			14			12			15			142			14			111
	Discount rate			5.25	%		4.5-5.25	%		4.25	%		3.75-4.25	%		4.75	%		4.75-5.25	%
	Expected return on plan assets			N/A			5	%		N/A			5	%		N/A			N/A
Deferred Compensation Plans	'
			Successor
			Year Ended December 31,		Year Ended December 31,		For the Period January 29, 2011 to December 31,
	(in millions)		2013		2012		2011
	Benefit obligation	$	250	$	163	$	114
	Interest expense	$	18	$	11	$	10

Equity_Tables

Equity (Tables)	12 Months Ended
	Dec. 31, 2013
Changes in Common Stock	'
	Common Stock Outstanding
	(in millions)	A	A Special	B
	Balance, January 1, 2011	2,072	695	9
	Stock compensation plans	20	1	-
	Repurchases and retirements of common stock	-	-95	-
	Employee stock purchase plans	3	-	-
	Balance, December 31, 2011	2,095	601	9
	Stock compensation plans	24	3	-
	Repurchases and retirements of common stock	-	-96	-
	Employee stock purchase plans	3	-	-
	Balance, December 31, 2012	2,122	508	9
	Stock compensation plans	14	-	-
	Repurchases and retirements of common stock	-	-49	-
	Employee stock purchase plans	2	-	-
	Balance, December 31, 2013	2,138	459	9
Aggregate Share Repurchases	'
	Share Repurchases
	Year ended December 31 (in millions)		2013		2012		2011
	Cash consideration	$	2,000	$	3,000	$	2,141
	Shares repurchased		49		96		95
Accumulated Other Comprehensive Income (Loss)	'
	Accumulated Other Comprehensive Income (Loss)
	December 31 (in millions)			2013		2012
	Unrealized gains (losses) on marketable securities		$	67	$	182
	Deferred gains (losses) on cash flow hedges			-45		-67
	Unrecognized gains (losses) on employee benefit obligations			71		-95
	Cumulative translation adjustments			-37		-5
	Accumulated other comprehensive income (loss), net of deferred taxes		$	56	$	15
NBCUniversal Media, LLC [Member]	'
Accumulated Other Comprehensive Income (Loss)	'
	Accumulated Other Comprehensive Income (Loss)
			Successor
	December 31 (in millions)		2013		2012
	Deferred gains (losses) on cash flow hedges		$	-5	$	-
	Unrecognized gains (losses) on employee benefit obligations			45		-50
	Cumulative translation adjustments			-56		-15
	Accumulated other comprehensive income (loss), net of deferred taxes		$	-16	$	-65

ShareBased_Compensation_Tables

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2013
Recognized Share-Based Compensation Expense	'
	Recognized Share-Based Compensation Expense
	Year ended December 31 (in millions)		2013		2012		2011
	Stock options	$	139	$	131	$	116
	Restricted share units		175		154		149
	Employee stock purchase plans		20		16		13
	Total	$	334	$	301	$	278
Stock Option Activity	'
	2013 Stock Options and Restricted Share Units
	As of December 31, 2013, unless otherwise stated (in millions, except per share data)			Stock Options		RSUs
	Awards granted during 2013			18		7
	Weighted-average exercise price		$	41.22
	Weighted-average fair value at grant date				$	38.28
	Stock options outstanding and nonvested RSUs(a)			104		26
	Weighted-average exercise price of stock options outstanding		$	25.49
	Weighted-average fair value at grant date of nonvested RSUs				$	25.38
Stock Option Fair Value and Significant Assumptions	'
	Year Ended December 31			2013			2012			2011
	RSUs fair value		$	38.28		$	27.8		$	22.78
	Stock options fair value		$	8.8		$	7.38		$	6.96
	Stock Option Valuation Assumptions:
		Dividend yield		1.9	%		2.2	%		1.8	%
		Expected volatility		25	%		29	%		28.1	%
		Risk-free interest rate		1.3	%		1.7	%		2.8	%
		Expected option life (in years)		7			7			7
NBCUniversal Media, LLC [Member]	'
Recognized Share-Based Compensation Expense	'
	Recognized Share-Based Compensation Expense
		Successor
	(in millions)	Year Ended December 31,		Year Ended December 31,		For the Period January 29, 2011 to December 31, 2011
		2013		2012
	Stock options	$	15	$	15	$	13
	Restricted share units		42		28		18
	Employee stock purchase plans		5		4		2
	Total	$	62	$	47	$	33
Stock Option Fair Value and Significant Assumptions	'
			Successor
			Year Ended December 31,			Year Ended December 31,			For the Period January 29, 2011 to December 31,
			2013			2012			2011
	RSUs fair value		$	37.79		$	27.51		$	21.75
	Stock options fair value		$	8.86		$	7.42		$	6.77
	Stock Option Valuation Assumptions:
		Dividend yield		1.9	%		2.2	%		1.8	%
		Expected volatility		25.2	%		29	%		28.5	%
		Risk-free interest rate		1.3	%		1.7	%		2.6	%
		Expected option life (in years)		7			7			7

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Components of Income Tax Expense	'
	Components of Income Tax Expense
	Year ended December 31 (in millions)			2013		2012		2011
	Current expense (benefit):
		Federal	$	3,183	$	3,004	$	1,480
		State		581		432		359
		Foreign		200		169		153
				3,964		3,605		1,992
	Deferred expense (benefit):
		Federal		-76		160		658
		State		108		-40		371
		Foreign		-16		19		29
				16		139		1,058
	Income tax expense		$	3,980	$	3,744	$	3,050
Schedule of Items That Effect Income Tax Expense	'
	Year ended December 31 (in millions)		2013		2012		2011
	Federal tax at statutory rate	$	3,890	$	4,063	$	2,872
	State income taxes, net of federal benefit		319		178		354
	Foreign income taxes, net of federal credit		15		92		89
	Nontaxable income attributable to noncontrolling interests		-103		-620		-410
	Adjustments to uncertain and effectively settled tax positions, net		58		114		77
	Accrued interest on uncertain and effectively settled tax positions, net		114		23		66
	Other		-313		-106		2
	Income tax expense	$	3,980	$	3,744	$	3,050
Components of Net Deferred Tax Liability	'
	Components of Net Deferred Tax Liability
	December 31 (in millions)			2013		2012
	Deferred Tax Assets:
		Net operating loss carryforwards	$	495	$	491
		Differences between book and tax basis of long-term debt		117		109
		Nondeductible accruals and other		3,588		1,771
		Less: Valuation allowance		405		355
				3,795		2,016
	Deferred Tax Liabilities:
		Differences between book and tax basis of property and equipment and intangible assets		34,044		29,185
		Differences between book and tax basis of investments		473		848
		Differences between book and tax basis of indexed debt securities		610		587
		Differences between book and tax basis of foreign subsidiaries and undistributed foreign earnings		367		-
		Differences between book and tax outside basis of NBCUniversal		-		1,413
				35,494		32,033
	Net deferred tax liability		$	31,699	$	30,017
Reconciliation of Unrecognized Tax Benefits	'
	Reconciliation of Unrecognized Tax Benefits
	(in millions)		2013		2012		2011
	Balance, January 1	$	1,573	$	1,435	$	1,251
	Additions based on tax positions related to the current year		90		154		87
	Additions based on tax positions related to prior years		201		79		75
	Additions from acquired subsidiaries		268		-		57
	Reductions for tax positions of prior years		-141		-60		-22
	Reductions due to expiration of statutes of limitations		-3		-3		-5
	Settlements with taxing authorities		-287		-32		-8
	Balance, December 31	$	1,701	$	1,573	$	1,435
NBCUniversal Media, LLC [Member]	'
Components of Income Tax Expense	'
	Components of Income Tax Expense
			Successor
							For the Period January 29, 2011 to December 31,
			Year Ended December 31,		Year Ended December 31,
	(in millions)		2013		2012		2011
	Foreign
		Current income tax expense	$	77	$	69	$	53
		Deferred income tax expense		-16		16		29
		Withholding tax expense		123		103		100
	U.S. domestic tax expense			22		9		3
	Income tax expense		$	206	$	197	$	185

Supplemental_Financial_Informa1

Supplemental Financial Information (Tables)	12 Months Ended
	Dec. 31, 2013
Receivables	'
	Receivables
	December 31 (in millions)		2013		2012
	Receivables, gross	$	6,972	$	6,026
	Less: Allowance for returns and customer incentives		375		307
	Less: Allowance for doubtful accounts		221		198
	Receivables, net	$	6,376	$	5,521
Supplemental cash flow disclosures	'
	Cash Payments for Interest and Income Taxes
	Year ended December 31 (in millions)		2013		2012		2011
	Interest	$	2,355	$	2,314	$	2,441
	Income taxes	$	3,946	$	2,841	$	1,626
NBCUniversal Media, LLC [Member]	'
Receivables	'
	Receivables
		Successor
	December 31 (in millions)		2013		2012
	Receivables, gross	$	5,348	$	4,381
	Less: Allowance for returns and customer incentives		372		307
	Less: Allowance for doubtful accounts		65		46
	Receivables, net	$	4,911	$	4,028
Supplemental cash flow disclosures	'
	Cash Payments for Interest and Income Taxes
		Successor						Predecessor
		Year Ended December 31,		Year Ended December 31,			For the Period January 29, 2011 to December 31,		For the Period January 1, 2011 to January 28,
	(in millions)	2013		2012			2011		2011
	Interest	$	462	$	461	$	444	$	1
	Income taxes	$	205	$	169	$	161	$	493
	Other Cash Flow Information
	As of January 28, 2011 (in millions)
	Cash and cash equivalents at end of Predecessor period	$	470
	Comcast Content Business contributed cash balances		38
	Cash and cash equivalents at beginning of Successor period	$	508

Receivables_Monetization_Table

Receivables Monetization (Tables)	12 Months Ended
	Dec. 31, 2013
Receivables Monetized and Deferred Consideration	'
	Receivables Monetized and Deferred Consideration
	December 31 (in millions)		2012
	Monetized receivables sold	$	791
	Deferred consideration	$	274
NBCUniversal Media, LLC [Member]	'
Receivables Monetized and Deferred Consideration	'
	Receivables Monetized and Deferred Consideration
		Successor
	December 31 (in millions)		2012
	Monetized receivables sold	$	791
	Deferred consideration	$	274

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments Disclosure [Table Text Block]	'
	As of December 31, 2013 (in millions)		Programming and Talent Commitments		Operating Leases
	2014	$	4,899	$	385
	2015	$	3,190	$	335
	2016	$	4,039	$	293
	2017	$	2,755	$	252
	2018	$	3,672	$	206
	Thereafter	$	20,522	$	673
Rental Expense [Table Text Block]	'
	The table below presents our rent expense charged to operations.
	Year ended December 31 (in millions)		2013		2012		2011
	Rent expense	$	616	$	688	$	570
NBCUniversal Media, LLC [Member]	'
Commitments Disclosure [Table Text Block]	'
	As of December 31, 2013 (in millions)		Programming and Talent Commitments		Operating Leases
	2014	$	4,876	$	164
	2015	$	3,182	$	133
	2016	$	4,035	$	117
	2017	$	2,755	$	107
	2018	$	3,672	$	92
	Thereafter	$	20,522	$	365
Rental Expense [Table Text Block]	'
	The table below presents our rent expense charged to operations.
		Successor						Predecessor
		Year Ended		Year Ended		For the Period January 29, 2011 to December 31, 2011		For the Period January 1, 2011 to January 28, 2011
		December 31,		December 31,
	(in millions)	2013		2012
	Rent expense	$	250	$	317	$	267	$	18

Financial_Data_by_Business_Seg1

Financial Data by Business Segment (Tables)	12 Months Ended
	Dec. 31, 2013														Dec. 31, 2011
Financial Data by Business Segment	'														'
	(in millions)			Revenue(f)		Operating Income (Loss) Before Depreciation and Amortization(g)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets	(in millions)			Revenue(f)		Operating Income (Loss) Before Depreciation and Amortization(g)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures
	2013														2011
	Cable Communications(a)		$	41,836	$	17,205	$	6,394	$	10,811	$	5,403	$	132,082	Cable Communications(a)		$	37,226	$	15,288	$	6,395	$	8,893	$	4,806
	NBCUniversal														NBCUniversal
		Cable Networks		9,201		3,501		734		2,767		67		29,413		Cable Networks		8,061		3,199		712		2,487		48
		Broadcast Television		7,120		345		98		247		65		6,723		Broadcast Television		5,982		124		85		39		61
		Filmed Entertainment		5,452		483		15		468		9		3,549		Filmed Entertainment		4,239		27		19		8		6
		Theme Parks		2,235		1,004		300		704		580		6,608		Theme Parks(c)		1,874		830		201		629		154
		Headquarters and Other(d)		31		-588		264		-852		439		6,002		Headquarters and Other(d)		45		-484		168		-652		165
		Eliminations(e)		-389		-13		-		-13		-		-556		Eliminations(e)		-941		-234		-53		-181		-
	NBCUniversal			23,650		4,732		1,411		3,321		1,160		51,739	NBCUniversal			19,260		3,462		1,132		2,330		434
	Corporate and Other			600		-489		66		-555		33		8,152	Corporate and Other			558		-416		93		-509		67
	Eliminations(e)			-1,429		-14		-		-14		-		-33,160	Eliminations(e)			-1,202		23		16		7		-
	Comcast Consolidated		$	64,657	$	21,434	$	7,871	$	13,563	$	6,596	$	158,813	Comcast Consolidated		$	55,842	$	18,357	$	7,636	$	10,721	$	5,307
	(in millions)			Revenue(f)		Operating Income (Loss) Before Depreciation and Amortization(g)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2012
	Cable Communications(a)		$	39,604	$	16,255	$	6,405	$	9,850	$	4,921	$	127,044
	NBCUniversal
		Cable Networks		8,727		3,303		735		2,568		150		29,636
		Broadcast Television(b)		8,200		358		97		261		65		6,414
		Filmed Entertainment		5,159		79		16		63		7		3,769
		Theme Parks		2,085		953		268		685		272		6,266
		Headquarters and Other(d)		43		-603		210		-813		269		8,938
		Eliminations(e)		-402		17		-		17		-		-561
	NBCUniversal			23,812		4,107		1,326		2,781		763		54,462
	Corporate and Other			498		-376		67		-443		30		6,000
	Eliminations(e)			-1,344		-9		-		-9		-		-22,535
	Comcast Consolidated		$	62,570	$	19,977	$	7,798	$	12,179	$	5,714	$	164,971
Cable Segment Revenue Sources	'														'
			2013		2012		2011
	Residential:
		Video	49.1	%	50.4	%	52.3	%
		High-speed Internet	24.7	%	24.1	%	23.5	%
		Voice	8.7	%	9	%	9.4	%
	Business services		7.7	%	6.5	%	5.2	%
	Advertising		5.2	%	5.8	%	5.4	%
	Other		4.6	%	4.2	%	4.2	%
	Total		100	%	100	%	100	%
NBCUniversal Media, LLC [Member]	'														'
Financial Data by Business Segment	'														'
	Successor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2013
		Cable Networks	$	9,201	$	3,501	$	734	$	2,767	$	67	$	29,413
		Broadcast Television		7,120		345		98		247		65		6,723
		Filmed Entertainment		5,452		483		15		468		9		3,549
		Theme Parks		2,235		1,004		300		704		580		6,608
		Headquarters and Other(c)		31		-588		264		-852		439		6,002
		Eliminations(d)		-389		-13		-		-13		-		-556
	Total		$	23,650	$	4,732	$	1,411	$	3,321	$	1,160	$	51,739
	Successor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures		Assets
	2012
		Cable Networks	$	8,727	$	3,303	$	735	$	2,568	$	150	$	29,636
		Broadcast Television(a)		8,200		358		97		261		65		6,414
		Filmed Entertainment		5,159		79		16		63		7		3,769
		Theme Parks		2,085		953		268		685		272		6,266
		Headquarters and Other(c)		43		-603		210		-813		269		8,938
		Eliminations(d)		-402		17		-		17		-		-561
	Total		$	23,812	$	4,107	$	1,326	$	2,781	$	763	$	54,462
	Successor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures
	For the Period January 29, 2011 to December 31, 2011
		Cable Networks	$	7,829	$	3,133	$	694	$	2,439	$	46
		Broadcast Television		5,982		124		85		39		61
		Filmed Entertainment		4,239		27		19		8		6
		Theme Parks(b)		1,874		830		201		629		154
		Headquarters and Other(c)		45		-484		114		-598		165
		Eliminations(d)		-941		-234		-		-234		-
	Total		$	19,028	$	3,396	$	1,113	$	2,283	$	432
	Predecessor (in millions)			Revenue(e)(g)		Operating Income (Loss) Before Depreciation and Amortization(f)		Depreciation and Amortization		Operating Income (Loss)		Capital Expenditures
	For the Period January 1, 2011 to January 28, 2011
		Cable Networks	$	385	$	145	$	3	$	142	$	1
		Broadcast Television		468		-18		6		-24		1
		Filmed Entertainment		353		1		2		-1		1
		Theme Parks(b)		115		37		14		23		9
		Headquarters and Other(c)		5		-99		2		-101		4
		Eliminations(d)		-120		-31		-		-31		-
	Total		$	1,206	$	35	$	27	$	8	$	16
Cable Segment Revenue Sources	'														'
			Successor								Predecessor
				Year Ended December 31,		Year Ended December 31,		For the Period January 29, 2011 to December 31, 2011			For the Period January 1, 2011 to January 28, 2011
		(in millions)		2013		2012
		Revenue:
		United States	$	18,887	$	19,348	$	14,927			$	935
		Foreign	$	4,763	$	4,464	$	4,101			$	271

Quarterly_Financial_Informatio1

Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Information	'
Quarterly Financial Information (Unaudited)	'
	(in millions, except per share data)		First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Total Year
	2013
	Revenue	$	15,310	$	16,270	$	16,151	$	16,926	$	64,657
	Operating income	$	3,067	$	3,435	$	3,414	$	3,647	$	13,563
	Net income attributable to Comcast Corporation	$	1,437	$	1,734	$	1,732	$	1,913	$	6,816
	Basic earnings per common share attributable to Comcast Corporation shareholders	$	0.55	$	0.66	$	0.66	$	0.73	$	2.6
	Diluted earnings per common share attributable to Comcast Corporation shareholders	$	0.54	$	0.65	$	0.65	$	0.72	$	2.56
	Dividends declared per common share	$	0.195	$	0.195	$	0.195	$	0.195	$	0.78
	2012
	Revenue	$	14,878	$	15,211	$	16,544	$	15,937	$	62,570
	Operating income	$	2,758	$	3,079	$	3,048	$	3,294	$	12,179
	Net income attributable to Comcast Corporation	$	1,224	$	1,348	$	2,113	$	1,518	$	6,203
	Basic earnings per common share attributable to Comcast Corporation shareholders	$	0.45	$	0.5	$	0.79	$	0.57	$	2.32
	Diluted earnings per common share attributable to Comcast Corporation shareholders	$	0.45	$	0.5	$	0.78	$	0.56	$	2.28
	Dividends declared per common share	$	0.1625	$	0.1625	$	0.1625	$	0.1625	$	0.65

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	12 Months Ended
	Dec. 31, 2013
Condensed Consolidating Financial Information [Abstract]	'
Condensed Consolidating Financial Statements	'
	Condensed Consolidating Balance Sheet
	December 31, 2013 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Assets
		Cash and cash equivalents	$	-	$	-	$	-	$	-	$	336	$	1,382	$	-	$	1,718
		Investments		-		-		-		-		-		3,573		-		3,573
		Receivables, net		-		-		-		-		-		6,376		-		6,376
		Programming rights		-		-		-		-		-		928		-		928
		Other current assets		237		-		-		-		35		1,208		-		1,480
	Total current assets			237		-		-		-		371		13,467		-		14,075
	Film and television costs			-		-		-		-		-		4,994		-		4,994
	Investments			11		-		-		-		374		3,385		-		3,770
	Investments in and amounts due from subsidiaries eliminated upon consolidation			79,956		97,429		102,673		54,724		40,644		85,164		-460,590		-
	Property and equipment, net			220		-		-		-		-		29,620		-		29,840
	Franchise rights			-		-		-		-		-		59,364		-		59,364
	Goodwill			-		-		-		-		-		27,098		-		27,098
	Other intangible assets, net			11		-		-		-		-		17,318		-		17,329
	Other noncurrent assets, net			1,078		145		-		-		103		1,899		-882		2,343
	Total assets		$	81,513	$	97,574	$	102,673	$	54,724	$	41,492	$	242,309	$	-461,472	$	158,813
	Liabilities and Equity
		Accounts payable and accrued expenses related to trade creditors	$	8	$	-	$	-	$	-	$	-	$	5,520	$	-	$	5,528
		Accrued participations and residuals		-		-		-		-		-		1,239		-		1,239
		Accrued expenses and other current liabilities		1,371		266		180		47		323		6,678		-		8,865
		Current portion of long-term debt		2,351		-		-		-		903		26		-		3,280
	Total current liabilities			3,730		266		180		47		1,226		13,463		-		18,912
	Long-term debt, less current portion			25,170		132		1,827		1,505		10,236		5,697		-		44,567
	Deferred income taxes			-		777		-		-		59		31,840		-741		31,935
	Other noncurrent liabilities			1,919		-		-		-		931		8,675		-141		11,384
	Redeemable noncontrolling interests
		and redeemable subsidiary preferred stock		-		-		-		-		-		957		-		957
	Equity:
		Common stock		30		-		-		-		-		-		-		30
		Other shareholders’ equity		50,664		96,399		100,666		53,172		29,040		181,313		-460,590		50,664
	Total Comcast Corporation shareholders’ equity			50,694		96,399		100,666		53,172		29,040		181,313		-460,590		50,694
	Noncontrolling interests			-		-		-		-		-		364		-		364
	Total equity			50,694		96,399		100,666		53,172		29,040		181,677		-460,590		51,058
	Total liabilities and equity		$	81,513	$	97,574	$	102,673	$	54,724	$	41,492	$	242,309	$	-461,472	$	158,813
	Condensed Consolidating Balance Sheet
	December 31, 2012 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Assets
		Cash and cash equivalents	$	-	$	-	$	-	$	-	$	5,129	$	5,822	$	-	$	10,951
		Investments		-		-		-		-		-		1,464		-		1,464
		Receivables, net		-		-		-		-		3		5,518		-		5,521
		Programming rights		-		-		-		-		-		909		-		909
		Other current assets		233		-		14		4		51		844		-		1,146
	Total current assets			233		-		14		4		5,183		14,557		-		19,991
	Film and television costs			-		-		-		-		-		5,054		-		5,054
	Investments			-		-		-		-		529		5,796		-		6,325
	Investments in and amounts due from subsidiaries eliminated upon consolidation			74,227		87,630		96,853		50,242		38,464		73,298		-420,714		-
	Property and equipment, net			242		-		-		-		-		26,990		-		27,232
	Franchise rights			-		-		-		-		-		59,364		-		59,364
	Goodwill			-		-		-		-		-		26,985		-		26,985
	Other intangible assets, net			12		-		-		-		-		17,828		-		17,840
	Other noncurrent assets, net			1,130		147		1		-		152		1,650		-900		2,180
	Total assets		$	75,844	$	87,777	$	96,868	$	50,246	$	44,328	$	231,522	$	-421,614	$	164,971
	Liabilities and Equity
		Accounts payable and accrued expenses related to trade creditors	$	8	$	-	$	-	$	-	$	-	$	6,198	$	-	$	6,206
		Accrued participations and residuals		-		-		-		-		-		1,350		-		1,350
		Accrued expenses and other current liabilities		1,290		275		210		54		263		4,690		-		6,782
		Current portion of long-term debt		-		-		2,105		241		7		23		-		2,376
	Total current liabilities			1,298		275		2,315		295		270		12,261		-		16,714
	Long-term debt, less current portion			23,306		113		1,827		1,512		11,219		105		-		38,082
	Deferred income taxes			-		754		-		-		78		30,035		-757		30,110
	Other noncurrent liabilities			1,884		-		-		-		926		10,604		-143		13,271
Redeemable noncontrolling interests
	and redeemable subsidiary preferred stock		-		-		-		-		-		16,998		-		16,998
Equity:
	Common stock		31		-		-		-		-		-		-		31
	Other shareholders’ equity		49,325		86,635		92,726		48,439		31,835		161,079		-420,714		49,325
Total Comcast Corporation shareholders’ equity			49,356		86,635		92,726		48,439		31,835		161,079		-420,714		49,356
Noncontrolling interests			-		-		-		-		-		440		-		440
Total equity			49,356		86,635		92,726		48,439		31,835		161,519		-420,714		49,796
Total liabilities and equity		$	75,844	$	87,777	$	96,868	$	50,246	$	44,328	$	231,522	$	-421,614	$	164,971
Condensed Consolidating Statement of Income
For the Year Ended December 31, 2013 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
Revenue:
	Service revenue	$	-	$	-	$	-	$	-	$	-	$	64,657	$	-	$	64,657
	Management fee revenue		897		-		874		548		-		-		-2,319		-
			897		-		874		548		-		64,657		-2,319		64,657
Costs and Expenses:
	Programming and production		-		-		-		-		-		19,670		-		19,670
	Other operating and administrative		403		-		874		548		855		18,223		-2,319		18,584
	Advertising, marketing and promotion		-		-		-		-		-		4,969		-		4,969
	Depreciation		30		-		-		-		-		6,224		-		6,254
	Amortization		5		-		-		-		-		1,612		-		1,617
			438		-		874		548		855		50,698		-2,319		51,094
Operating income (loss)			459		-		-		-		-855		13,959		-		13,563
Other Income (Expense):
	Interest expense		-1,523		-11		-212		-126		-488		-214		-		-2,574
	Investment income (loss), net		-		-13		-		-		3		586		-		576
	Equity in net income (losses) of
	investees, net		7,509		7,540		7,430		5,473		3,331		1,882		-33,251		-86
	Other income (expense), net		-2		-		2		-		-1		-363		-		-364
			5,984		7,516		7,220		5,347		2,845		1,891		-33,251		-2,448
Income (loss) before income taxes			6,443		7,516		7,220		5,347		1,990		15,850		-33,251		11,115
Income tax (expense) benefit			373		9		73		44		-22		-4,457		-		-3,980
Net income (loss)			6,816		7,525		7,293		5,391		1,968		11,393		-33,251		7,135
Net (income) loss attributable to
	noncontrolling interests and redeemable subsidiary preferred stock		-		-		-		-		-		-319		-		-319
Net income (loss) attributable to
	Comcast Corporation	$	6,816	$	7,525	$	7,293	$	5,391	$	1,968	$	11,074	$	-33,251	$	6,816
Comprehensive income (loss)
	attributable to Comcast Corporation	$	6,883	$	7,521	$	7,276	$	5,392	$	2,017	$	10,969	$	-33,175	$	6,883
Condensed Consolidating Statement of Income
For the Year Ended December 31, 2012 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
Revenue:
	Service revenue	$	-	$	-	$	-	$	-	$	-	$	62,570	$	-	$	62,570
	Management fee revenue		848		-		827		516		-		-		-2,191		-
			848		-		827		516		-		62,570		-2,191		62,570
Costs and Expenses:
	Programming and production		-		-		-		-		-		19,929		-		19,929
	Other operating and administrative		401		-		827		516		899		17,381		-2,191		17,833
	Advertising, marketing and promotion		-		-		-		-		-		4,831		-		4,831
	Depreciation		30		-		-		-		-		6,120		-		6,150
	Amortization		4		-		-		-		-		1,644		-		1,648
			435		-		827		516		899		49,905		-2,191		50,391
Operating income (loss)			413		-		-		-		-899		12,665		-		12,179
Other Income (Expense):
	Interest expense		-1,430		-23		-329		-135		-430		-174		-		-2,521
	Investment income (loss), net		8		3		-		-		5		203		-		219
	Equity in net income (losses) of
	investees, net		6,858		6,536		6,665		4,909		4,402		4,014		-32,425		959
	Other income (expense), net		2		-		-		-		-14		785		-		773
			5,438		6,516		6,336		4,774		3,963		4,828		-32,425		-570
Income (loss) before income taxes			5,851		6,516		6,336		4,774		3,064		17,493		-32,425		11,609
Income tax (expense) benefit			352		7		115		47		-9		-4,256		-		-3,744
Net income (loss)			6,203		6,523		6,451		4,821		3,055		13,237		-32,425		7,865
Net (income) loss attributable to
	noncontrolling interests and redeemable subsidiary preferred stock		-		-		-		-		-		-1,662		-		-1,662
Net (income) loss attributable
	to Comcast Corporation	$	6,203	$	6,523	$	6,451	$	4,821	$	3,055	$	11,575	$	-32,425	$	6,203
Comprehensive income (loss)
	attributable to Comcast Corporation	$	6,370	$	6,523	$	6,460	$	4,821	$	3,068	$	11,703	$	-32,575	$	6,370
Condensed Consolidating Statement of Income
For the Year Ended December 31, 2011 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
Revenue:
	Service revenue	$	-	$	-	$	-	$	-	$	-	$	55,842	$	-	$	55,842
	Management fee revenue		800		-		784		488		-		-		-2,072		-
			800		-		784		488		-		55,842		-2,072		55,842
Costs and Expenses:
	Programming and production		-		-		-		-		-		16,596		-		16,596
	Other operating and administrative		420		5		784		488		678		16,343		-2,072		16,646
	Advertising, marketing and promotion		-		-		-		-		-		4,243		-		4,243
	Depreciation		29		-		-		-		-		6,011		-		6,040
	Amortization		3		-		-		-		-		1,593		-		1,596
			452		5		784		488		678		44,786		-2,072		45,121
Operating income (loss)			348		-5		-		-		-678		11,056		-		10,721
Other Income (Expense):
	Interest expense		-1,439		-32		-338		-172		-370		-154		-		-2,505
	Investment income (loss), net		3		2		-		-		-		154		-		159
	Equity in net income (losses) of
	investees, net		4,879		5,734		5,598		3,361		2,793		1,648		-24,048		-35
	Other income (expense), net		-19		1		-		-		-59		-56		-		-133
			3,424		5,705		5,260		3,189		2,364		1,592		-24,048		-2,514
Income (loss) before income taxes			3,772		5,700		5,260		3,189		1,686		12,648		-24,048		8,207
Income tax (expense) benefit			388		12		118		60		-3		-3,625		-		-3,050
Net income (loss)			4,160		5,712		5,378		3,249		1,683		9,023		-24,048		5,157
Net (income) loss attributable to
	noncontrolling interests and redeemable subsidiary preferred stock		-		-		-		-		-		-997		-		-997
Net income (loss) attributable to
	Comcast Corporation	$	4,160	$	5,712	$	5,378	$	3,249	$	1,683	$	8,026	$	-24,048	$	4,160
Comprehensive income (loss)
	attributable to Comcast Corporation	$	4,107	$	5,712	$	5,387	$	3,249	$	1,605	$	8,064	$	-24,017	$	4,107
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2013 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Net cash provided by (used in) operating activities	$	-600	$	-3	$	-151	$	-94	$	-1,102	$	16,110	$	-	$	14,160
Investing Activities:
	Net transactions with affiliates		66		3		2,248		332		-470		-2,179		-		-
	Capital expenditures		-7		-		-		-		-		-6,589		-		-6,596
	Cash paid for intangible assets		-4		-		-		-		-		-1,005		-		-1,009
	Acquisitions of real estate properties		-		-		-		-		-		-1,904		-		-1,904
	Acquisitions, net of cash acquired		-		-		-		-		-		-99		-		-99
	Proceeds from sales of businesses and investments		-		-		-		-		2		1,081		-		1,083
	Return of capital from investees		-		-		-		-		128		21		-		149
	Purchases of investments		-11		-		-		-		-3		-1,209		-		-1,223
	Other		-		-		-		-		-20		105		-		85
	Net cash provided by (used in) investing activities		44		3		2,248		332		-363		-11,778		-		-9,514
Financing Activities:
	Proceeds from (repayments of) short-term borrowings, net		1,349		-		-		-		-		-4		-		1,345
	Proceeds from borrowings		2,933		-		-		-		-		-		-		2,933
	Repurchases and repayments of debt		-		-		-2,097		-238		-88		-21		-		-2,444
	Repurchases and retirements of common stock		-2,000		-		-		-		-		-		-		-2,000
	Dividends paid		-1,964		-		-		-		-		-		-		-1,964
	Issuances of common stock		40		-		-		-		-		-		-		40
	Purchase of NBCUniversal noncontrolling common equity interest		-		-		-		-		-3,200		-7,561		-		-10,761
	Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock		-		-		-		-		-		-215		-		-215
	Settlement of Station Venture liability		-		-		-		-		-		-602		-		-602
	Other		198		-		-		-		-40		-369		-		-211
	Net cash provided by (used in) financing activities		556		-		-2,097		-238		-3,328		-8,772		-		-13,879
Increase (decrease) in cash and cash equivalents			-		-		-		-		-4,793		-4,440		-		-9,233
Cash and cash equivalents, beginning of year			-		-		-		-		5,129		5,822		-		10,951
Cash and cash equivalents, end of year		$	-		-		-		-		336		1,382		-		1,718
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2012 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Net cash provided by (used in) operating activities	$	-362	$	-7	$	-177	$	-114	$	-1,347	$	16,861	$	-	$	14,854
Investing Activities:
	Net transactions with affiliates		3,845		206		177		667		4,850		-9,745		-		-
	Capital expenditures		-10		-		-		-		-		-5,704		-		-5,714
	Cash paid for intangible assets		-6		-		-		-		-		-917		-		-923
	Acquisitions, net of cash acquired		-		-		-		-		-		-90		-		-90
	Proceeds from sales of businesses and investments		-		-		-		-		-		3,102		-		3,102
	Return of capital from investees		-		-		-		-		-		2,362		-		2,362
	Purchases of investments		-		-		-		-		-19		-278		-		-297
	Other		-		3		-		-		-22		93		-		74
	Net cash provided by (used in) investing activities		3,829		209		177		667		4,809		-11,177		-		-1,486
Financing Activities:
	Proceeds from (repayments of) short-term borrowings, net		-1		-		-		-		-550		7		-		-544
	Proceeds from borrowings		2,536		-		-		-		1,995		13		-		4,544
	Repurchases and repayments of debt		-1,726		-202		-		-553		-2		-398		-		-2,881
	Repurchases and retirements of common stock		-3,000		-		-		-		-		-		-		-3,000
	Dividends paid		-1,608		-		-		-		-		-		-		-1,608
	Issuances of common stock		233		-		-		-		-		-		-		233
	Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock		-		-		-		-		-		-691		-		-691
	Other		99		-		-		-		-14		-175		-		-90
	Net cash provided by (used in) financing activities		-3,467		-202		-		-553		1,429		-1,244		-		-4,037
Increase (decrease) in cash and cash equivalents			-		-		-		-		4,891		4,440		-		9,331
Cash and cash equivalents, beginning of year			-		-		-		-		238		1,382		-		1,620
Cash and cash equivalents, end of year		$	-	$	-	$	-	$	-	$	5,129	$	5,822	$	-	$	10,951
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2011 (in millions)			Comcast Parent		Comcast Holdings		CCCL Parent		Combined CCHMO Parents		NBCUniversal Media Parent		Non- Guarantor Subsidiaries		Elimination and Consolidation Adjustments		Consolidated Comcast Corporation
	Net cash provided by (used in) operating activities	$	-513	$	-19	$	-209	$	-131	$	-638	$	15,855	$	-	$	14,345
Investing Activities:
	Net transactions with affiliates		4,615		19		1,209		131		247		-6,221		-		-
	Capital expenditures		-7		-		-		-		-		-5,300		-		-5,307
	Cash paid for intangible assets		-2		-		-		-		-		-952		-		-954
	Acquisitions, net of cash acquired		-		-		-		-		295		-6,702		-		-6,407
	Proceeds from sales of businesses and investments		-		-		-		-		3		274		-		277
	Return of capital from investees		-		-		-		-		-		37		-		37
	Purchases of investments		-		-		-		-		-4		-131		-		-135
	Other		-		-		-		-		-		-19		-		-19
	Net cash provided by (used in) investing activities		4,606		19		1,209		131		541		-19,014		-		-12,508
Financing Activities:
	Proceeds from (repayments of) short-term borrowings, net		-4		-		-		-		550		-2		-		544
	Repurchases and repayments of debt		-1,095		-		-1,000		-		-		-1,121		-		-3,216
	Repurchases and retirements of common stock		-2,141		-		-		-		-		-		-		-2,141
	Dividends paid		-1,187		-		-		-		-		-		-		-1,187
	Issuances of common stock		283		-		-		-		-		-		-		283
	Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock		-		-		-		-		-		-325		-		-325
	Other		51		-		-		-		-215		5		-		-159
	Net cash provided by (used in) financing activities		-4,093		-		-1,000		-		335		-1,443		-		-6,201
Increase (decrease) in cash and cash equivalents			-		-		-		-		238		-4,602		-		-4,364
Cash and cash equivalents, beginning of year			-		-		-		-		-		5,984		-		5,984
Cash and cash equivalents, end of year		$	-	$	-	$	-	$	-	$	238	$	1,382	$	-	$	1,620

Schedule_II_Valuation_and_Qual1

Schedule II Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2013
Schedule II-Valuation and Qualifying Accounts	'
	Comcast Corporation and Subsidiaries
	Schedule II — Valuation and Qualifying Accounts
	Year ended December 31, 2013, 2012 and 2011
	Year Ended December 31 (in millions)			Balance at Beginning of Year		Additions Charged to Costs and Expenses		Deductions from Reserves		Balance at End of Year
	2013
		Allowance for doubtful accounts	$	198	$	317	$	294	$	221
		Allowance for returns and customer incentives		307		528		460		375
		Valuation allowance on deferred tax assets		355		71		21		405
	2012
		Allowance for doubtful accounts	$	202	$	293	$	297	$	198
		Allowance for returns and customer incentives		425		599		717		307
		Valuation allowance on deferred tax assets		297		61		3		355
	2011
		Allowance for doubtful accounts	$	173	$	306	$	277	$	202
		Allowance for returns and customer incentives		-		536		111		425
		Valuation allowance on deferred tax assets		207		103		13		297
NBCUniversal Media, LLC [Member]	'
Schedule II-Valuation and Qualifying Accounts	'
	NBCUniversal Media, LLC
	Schedule II — Valuation and Qualifying Accounts
	(in millions)			Balance at Beginning of Period		Additions Charged to Costs and Expenses		Deductions from Reserves		Balance at End of Period
	Successor
	Year ended December 31, 2013
		Allowance for doubtful accounts	$	46	$	33	$	14	$	65
		Allowance for returns and customer incentives		307		525		460		372
		Valuation allowance on deferred tax assets		73		8		21		60
	Year ended December 31, 2012
		Allowance for doubtful accounts	$	34	$	19	$	7	$	46
		Allowance for returns and customer incentives		425		599		717		307
		Valuation allowance on deferred tax assets		53		23		3		73
	Period January 29, 2011 through December 31, 2011
		Allowance for doubtful accounts	$	7	$	35	$	8	$	34
		Allowance for returns and customer incentives		-		536		111		425
		Valuation allowance on deferred tax assets		57		9		13		53

Business_and_Basis_of_Presenta1

Business and Basis of Presentation (Details)	Mar. 19, 2013	Mar. 19, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
		NBCUniversal Media, LLC [Member]	Video Customers [Member]	High-speed Internet Customers [Member]	Phone Customers [Member]
			numberofcustomers	numberofcustomers	numberofcustomers
Number of customers	'	'	21,700,000	20,700,000	10,700,000
Remaining equity interest acquired	49.00%	49.00%	'	'	'

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share	'	'	'	'	'	'	'	'	'	'	'
Excluded shares from diluted EPS because their inclusion would have an antidilutive effect	'	'	'	'	'	'	'	'	'	'	45
Net income attributable to Parent	$1,913	$1,732	$1,734	$1,437	$1,518	$2,113	$1,348	$1,224	$6,816	$6,203	$4,160
Basic shares attributable to Comcast Corporation shareholders	'	'	'	'	'	'	'	'	2,625	2,678	2,746
Assumed exercise or issuance of shares relating to stock plans	'	'	'	'	'	'	'	'	40	39	32
Diluted shares attributable to Comcast Corporation shareholders	'	'	'	'	'	'	'	'	2,665	2,717	2,778
Basic earnings per common share attributable to Comcast Corporation shareholders	$0.73	$0.66	$0.66	$0.55	$0.57	$0.79	$0.50	$0.45	$2.60	$2.32	$1.51
Diluted earnings per common share attributable to Comcast Corporation shareholders	$0.72	$0.65	$0.65	$0.54	$0.56	$0.78	$0.50	$0.45	$2.56	$2.28	$1.50

Significant_Transactions_Narra

Significant Transactions (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 19, 2013	Jan. 28, 2011
Significant Transactions [Line Items]	'	'	'	'	'
Purchase of NBCUniversal noncontrolling interest	$16,700,000,000	'	'	'	'
Ownership Percentage In New Company	'	'	51.00%	'	51.00%
Cash paid to acquire entity including transaction related costs	'	'	'	'	6,200,000,000
Remaining equity interest acquired	'	'	'	49.00%	'
Acquisitions, net of cash acquired	99,000,000	90,000,000	6,407,000,000	'	'
Deferred income taxes	31,935,000,000	30,110,000,000	'	'	'
NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Purchase of NBCUniversal noncontrolling interest	16,700,000,000	'	'	'	'
Cash paid to acquire entity including transaction related costs	'	'	'	'	6,200,000,000
Remaining equity interest acquired	'	'	'	49.00%	'
Redemption percentage	15.00%	'	'	'	'
Comcast Corporation [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Ownership percentage in NBCUniversal Holdings	96.00%	'	'	'	'
NBCUniversal [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Deferred income tax liabilities	'	'	'	'	35,000,000
Goodwill	'	'	'	'	10,900,000,000
Universal Orlando [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Remaining equity interest acquired	'	'	50.00%	'	'
Cash paid to acquire entity, net	'	'	1,000,000,000	'	'
Universal Orlando [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Remaining equity interest acquired	'	'	50.00%	'	'
Cash paid to acquire entity, net	'	'	1,000,000,000	'	'
Comcast Cash On Hand	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	11,400,000,000	'	'	'	'
Comcast Cash On Hand | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	11,400,000,000	'	'	'	'
NBCUniversal Cash On Hand [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Portion Of Consideration Transferred Funded By NBCUniversal	4,600,000,000	'	'	'	'
NBCUniversal Enterprise Senior Unsecured Debt Securities	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	4,000,000,000	'	'	'	'
NBCUniversal Enterprise Senior Unsecured Debt Securities | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	4,000,000,000	'	'	'	'
Comcast Commercial Paper Program	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	750,000,000	'	'	'	'
Comcast Commercial Paper Program | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	750,000,000	'	'	'	'
NBCUniversal Enterprise Credit Facility	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	1,250,000,000	'	'	'	'
NBCUniversal Enterprise Credit Facility | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	1,250,000,000	'	'	'	'
NBCUniversal Enterprise Preferred Stock	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	725,000,000	'	'	'	'
Fair Value Amount Of Redeemable Preferred Stock	741,000,000	'	'	'	'
NBCUniversal Enterprise Preferred Stock | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	725,000,000	'	'	'	'
Nbcuniversal Holdings Preferred Stock [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Preferred stock dividend rate percentage	8.25%	'	'	'	'
Preferred stock liquidition preference value	9,400,000,000	'	'	'	'
Preferred stock dividend reset rate percentage description	'On March 1, 2018, and thereafter on every fifth anniversary of such date, this rate will reset to 7.44% plus the yield on actively traded United States Treasury securities having a 5 year maturity.	'	'	'	'
30 Rockefeller Plaza And Englewood Cliffs [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Payments related to acquisition of real estate properties	1,400,000,000	'	'	'	'
30 Rockefeller Plaza And Englewood Cliffs [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Payments related to acquisition of real estate properties	1,400,000,000	'	'	'	'
NBCUniversal Enterprise [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Preferred stock dividend rate percentage	5.25%	'	'	'	'
NBCUniversal Enterprise [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Ownership percentage in NBCUniversal Holdings	4.00%	'	'	'	'
NBCUniversal Transaction [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Deferred income taxes	'	'	'	'	576,000,000
Theme Parks Segment [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Goodwill	'	'	982,000,000	'	'
Theme Parks Segment [Member] | NBCUniversal Media, LLC [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Goodwill	'	'	982,000,000	'	'
Redemption Transaction [Member]	'	'	'	'	'
Significant Transactions [Line Items]	'	'	'	'	'
Deferred income taxes	$1,600,000,000	'	'	'	'

Related_Party_Transactions_Nar

Related Party Transactions (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
Settlement Of Station Venture Liability	$602,000,000
NBCUniversal Media, LLC [Member]	'
Redemption Transaction Distribution	3,200,000,000
Revolving Credit Agreement Capacity	3,000,000,000
Settlement Of Station Venture Liability	602,000,000
Collateral Liability For Unconsolidated Subsidiary Debt	482,000,000
Borrowing margin for LIBOR based borrowings	1.00%
Nbcuniversal Holdings Preferred Stock [Member] | NBCUniversal Media, LLC [Member]	'
Preferred stock liquidition preference value	$9,400,000,000
Preferred stock dividend rate percentage	8.25%

Related_Party_Transactions_Con

Related Party Transactions - Consolidated Balance Sheet (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Receivables, net	$6,376	$5,521
Accounts payable and accrued expenses related to trade creditors	5,528	6,206
Accrued expenses and other current liabilities	7,967	5,931
Other noncurrent liabilities	11,384	13,271
NBCUniversal Media, LLC [Member]	'	'
Receivables, net	4,911	4,028
Note payable to Comcast	799	'
Accounts payable and accrued expenses related to trade creditors	1,583	2,348
Accrued expenses and other current liabilities	1,465	1,288
Other noncurrent liabilities	3,412	3,746
Comcast And Consolidated Subsidiaries [Member] | NBCUniversal Media, LLC [Member]	'	'
Receivables, net	228	204
Note payable to Comcast	799	'
Accounts payable and accrued expenses related to trade creditors	56	25
Accrued expenses and other current liabilities	37	1
Other noncurrent liabilities	$383	'

Related_Party_Transactions_Con1

Related Party Transactions - Consolidated Statement of Income (Details) (USD $)

3 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

11 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Comcast And Consolidated Subsidiaries [Member]

Comcast And Consolidated Subsidiaries [Member]

Comcast And Consolidated Subsidiaries [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Revenue

$16,926

$16,151

$16,270

$15,310

$15,937

$16,544

$15,211

$14,878

$64,657

$62,570

$55,842

$1,206

$19,028

$23,650

$23,812

$1,025

$1,262

$1,228

Operating costs and expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

($72)

($190)

($175)

Film_and_Television_Costs_Film

Film and Television Costs (Film and Television Costs)(Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Film And Television Costs [Line Items]	'	'
Programming rights, less amortization	$2,039	$1,886
Total film costs, television costs and programming rights	5,922	5,963
Less: Current portion of programming rights	928	909
Film and television costs	4,994	5,054
NBCUniversal Media, LLC [Member]	'	'
Film And Television Costs [Line Items]	'	'
Programming rights, less amortization	2,003	1,808
Total film costs, television costs and programming rights	5,886	5,885
Less: Current portion of programming rights	903	844
Film and television costs	4,983	5,041
Film Costs [Member]	'	'
Film And Television Costs [Line Items]	'	'
Released, less amortization	1,630	1,472
Completed, not released	70	99
In production and in development	658	1,048
Total film costs	2,358	2,619
Film Costs [Member] | NBCUniversal Media, LLC [Member]	'	'
Film And Television Costs [Line Items]	'	'
Released, less amortization	1,630	1,472
Completed, not released	70	99
In production and in development	658	1,048
Total film costs	2,358	2,619
Television Costs [Member]	'	'
Film And Television Costs [Line Items]	'	'
Released, less amortization	1,155	1,124
In production and in development	370	334
Total television costs	1,525	1,458
Television Costs [Member] | NBCUniversal Media, LLC [Member]	'	'
Film And Television Costs [Line Items]	'	'
Released, less amortization	1,155	1,124
In production and in development	370	334
Total television costs	$1,525	$1,458

Film_and_Television_Costs_Narr

Film and Television Costs (Narrative)(Details) (USD $)	Dec. 31, 2013
Amortization of completed film and television production expected to be amortized during the next fiscal year	$1,300,000,000
Expected amortization percentage of released and unamortized film and television costs	85.00%
Remaining unamortized costs of acquired film and television libraries	711,000,000
Expected amortization percentage of unamortized film and television library costs during the next three fiscal years	49.00%
NBCUniversal Media, LLC [Member]	'
Amortization of completed film and television production expected to be amortized during the next fiscal year	1,300,000,000
Expected amortization percentage of released and unamortized film and television costs	85.00%
Remaining unamortized costs of acquired film and television libraries	$711,000,000
Expected amortization percentage of unamortized film and television library costs during the next three fiscal years	49.00%

Investments_Details

Investments (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair value method	$4,345	$4,493
Equity method	989	1,164
Cost method	2,009	2,132
Total Investments	7,343	7,789
Less: Current investments	3,573	1,464
Noncurrent investments	3,770	6,325
NBCUniversal Media, LLC [Member]	'	'
Fair value method	11	21
Equity method	852	1,016
Cost method	21	229
Total Investments	884	1,266
Other Equity Method Investments [Member]	'	'
Equity method	469	693
Other Equity Method Investments [Member] | NBCUniversal Media, LLC [Member]	'	'
Equity method	332	545
Air Touch [Member]	'	'
Cost method	1,553	1,538
Other Cost Method Investment [Member]	'	'
Cost method	456	594
The Weather Channel [Member]	'	'
Equity method	333	471
The Weather Channel [Member] | NBCUniversal Media, LLC [Member]	'	'
Equity method	333	471
Hulu [Member]	'	'
Equity method	187	'
Hulu [Member] | NBCUniversal Media, LLC [Member]	'	'
Equity method	$187	'

Investments_Investment_Income_

Investments (Investment Income (Loss), Net) (Details) (USD $)	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Gains on sales and exchanges of investments, net	$484	$30	$41	'	'	'	'
Investment impairment losses	-29	-24	-5	'	'	'	'
Unrealized gains (losses) on securities underlying prepaid forward sale agreements	1,601	1,159	192	'	'	'	'
Mark to market adjustments on derivative component of prepaid forward sale agreements and indexed debt instruments	-1,604	-1,071	-119	'	'	'	'
Interest and dividend income	111	119	110	'	'	'	'
Other, net	13	6	-60	'	'	'	'
Investment income (loss), net	$576	$219	$159	$4	$19	$17	$27

Investments_Fair_Value_Method_

Investments (Fair Value Method Investments) (Details) (USD $)	12 Months Ended
Share data in Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair value equity securities held as collateral	$3,959,000,000	$4,143,000,000	'
Obligations under prepaid forward sale agreements	811,000,000	1,248,000,000	'
Derivative component of prepaid forward sale agreements	2,800,000,000	2,302,000,000	'
Total liabilities associated with prepaid forward sale agreements	3,611,000,000	3,550,000,000	'
Prepaid forward sale obligations fair value	3,600,000,000	3,600,000,000	'
Fair value method	4,345,000,000	4,493,000,000	'
Prepaid Forward Obligations Settlement	1,600,000,000	'	'
Total equity securities used to settle prepaid forward obligations	1,400,000,000	'	'
Equity securities held as collateral under our prepaid forward sale agreements acquired during the period	657,000,000	'	'
Proceeds From Sales Of Businesses And Investments	1,083,000,000	3,102,000,000	277,000,000
NBCUniversal Media, LLC [Member]	'	'	'
Fair value method	11,000,000	21,000,000	'
Clearwire LLC [Member]	'	'	'
Proceeds from sale of available-for-sale securities	443,000,000	'	'
Pre-tax gain realized on Clearwire	443,000,000	'	'
Fair Value Investment Shares Sold	89	'	'
Liberty Media Redemption Transaction [Member]	'	'	'
Shares Redeemed	6.3	'	'
Proceeds From Sales Of Businesses And Investments	417,000,000	'	'
Fair value of the shares delivered in the Liberty Media exchange transaction	$937,000,000	'	'

Investments_Equity_Method_Inve

Investments (Equity Method Investments) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Return of capital from investees	$149	$2,362	$37
Impairment of investment	249	'	'
NBCUniversal Media, LLC [Member]	'	'	'
Impairment of investment	249	'	'
The Weather Channel [Member]	'	'	'
Total distribution from investee	152	'	'
Return of capital from investees	128	'	'
The Weather Channel [Member] | NBCUniversal Media, LLC [Member]	'	'	'
Total distribution from investee	152	'	'
Return of capital from investees	128	'	'
Hulu [Member]	'	'	'
Capital contribution agreement	247	'	'
Hulu [Member] | NBCUniversal Media, LLC [Member]	'	'	'
Capital contribution agreement	$247	'	'

Investments_Cost_Method_Invest

Investments (Cost Method Investments) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Air Touch [Member]	'	'
Fair value of AirTouch preferred stock related to redeemable preferred shares	$1,700,000,000	$1,800,000,000
Aggregate redemption value	1,750,000,000	'
Carrying amount of redeemable preferred stock	1,500,000,000	1,500,000,000
Fair value amount of redeemable preferred stock	1,700,000,000	1,800,000,000
Nonredeemable preferred stock	100,000,000	100,000,000
Preferred Shares Redeemable in April 2020 [Member]	'	'
Aggregate redemption value	$1,650,000,000	'

Property_and_Equipment_Details

Property and Equipment (Details) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Cable Distribution System [Member]

Customer Premise Equipment [Member]

Other Equipment [Member]

Buildings and Leasehold Improvements [Member]

Buildings and Leasehold Improvements [Member]

Furniture Fixtures And Equipment [Member]

Comcast Center [Member]

Acquisition Of Real Estate Properties [Member]

Acquisition Of Real Estate Properties [Member]

numberofyears

numberofyears

numberofyears

numberofyears

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

numberofyears

numberofyears

Weighted average original useful life (in years)

'

'

'

'

11

6

5

21

20

6

'

'

'

Cable distribution system

$30,498,000,000

$29,528,000,000

'

'

'

'

'

'

'

'

'

'

'

Customer premise equipment

25,949,000,000

24,763,000,000

'

'

'

'

'

'

'

'

'

'

'

Other equipment

6,826,000,000

5,909,000,000

'

'

'

'

'

'

'

'

'

'

'

Buildings and leasehold improvements

8,057,000,000

5,468,000,000

5,239,000,000

3,223,000,000

'

'

'

'

'

'

'

'

'

Land

1,084,000,000

989,000,000

799,000,000

728,000,000

'

'

'

'

'

'

'

'

'

Furniture, fixtures and equipment

'

'

2,383,000,000

1,961,000,000

'

'

'

'

'

'

'

'

'

Construction in process

'

'

828,000,000

552,000,000

'

'

'

'

'

'

'

'

'

Property and equipment, at cost

72,414,000,000

66,657,000,000

9,249,000,000

6,464,000,000

'

'

'

'

'

'

'

'

'

Less: Accumulated depreciation

42,574,000,000

39,425,000,000

1,599,000,000

1,083,000,000

'

'

'

'

'

'

'

'

'

Property and equipment, net

29,840,000,000

27,232,000,000

7,650,000,000

5,381,000,000

'

'

'

'

'

'

'

'

'

Increases in property and equpiment related to real estate acquisitions

'

'

'

'

'

'

'

'

'

'

'

$2,200,000,000

$1,700,000,000

Equity interest acquired

'

'

'

'

'

'

'

'

'

'

80.00%

'

'

Goodwill_Rollforward_Details

Goodwill Rollforward (Details) (USD $)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2011

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Msnbccom [Member]

Msnbccom [Member]

Other Acquisitions [Member]

Other Acquisitions [Member]

Cable Communications [Member]

Cable Communications [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Corporate and Other [Member]

Corporate and Other [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Msnbccom [Member]

Msnbccom [Member]

Other Acquisitions [Member]

Other Acquisitions [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Goodwill beginning balance

$26,985

$26,874

$14,770

$14,657

'

'

'

'

$12,208

$12,206

$13,026

$12,744

$13,026

$12,744

'

'

'

'

$761

$772

$761

$772

$1

$1

$1

$1

$1

$1

$1,140

$982

$1,140

$982

$9

$9

Acquisitions

42

'

42

'

227

227

79

79

'

'

39

'

39

'

227

227

79

79

3

'

3

'

'

'

'

'

'

'

'

'

'

'

'

'

Dispositions

'

-1

'

'

'

'

'

'

-1

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Adjustments

71

-194

70

-193

'

'

'

'

-1

'

65

-24

65

-24

'

'

'

'

5

-11

5

-11

'

'

'

'

'

'

-158

'

-158

'

1

'

Goodwill ending balance

$27,098

$26,985

$14,882

$14,770

'

'

'

'

$12,206

$12,206

$13,130

$13,026

$13,130

$13,026

'

'

'

'

$769

$761

$769

$761

$1

$1

$1

$1

$1

$1

$982

$982

$982

$982

$10

$9

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Intangible Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Franchise rights	$59,364	$59,364
Accumulated amortization	-8,874	-7,662
Total	85,567	84,866
NBCUniversal Media, LLC [Member]	'	'
Accumulated amortization	-4,003	-3,238
Total	18,860	18,658
Customer relationships	'	'
Finite-lived intangible assets, gross carrying amount	15,037	14,970
Accumulated amortization	-4,772	-3,971
Weighted average original useful life	'19 years 0 months 0 days	'
Customer relationships | NBCUniversal Media, LLC [Member]	'	'
Finite-lived intangible assets, gross carrying amount	13,086	13,026
Accumulated amortization	-2,982	-2,328
Weighted average original useful life	'19 years 0 months 0 days	'
Software	'	'
Finite-lived intangible assets, gross carrying amount	4,271	3,795
Accumulated amortization	-2,405	-2,123
Weighted average original useful life	'5 years 0 months 0 days	'
Software | NBCUniversal Media, LLC [Member]	'	'
Finite-lived intangible assets, gross carrying amount	522	409
Accumulated amortization	-240	-164
Weighted average original useful life	'5 years 0 months 0 days	'
Other agreements and rights	'	'
Finite-lived intangible assets, gross carrying amount	1,433	1,414
Accumulated amortization	-645	-609
Weighted average original useful life	'20 years 0 months 0 days	'
Other agreements and rights | NBCUniversal Media, LLC [Member]	'	'
Finite-lived intangible assets, gross carrying amount	1,511	1,507
Accumulated amortization	-781	-746
Weighted average original useful life	'21 years 0 months 0 days	'
Trade names	'	'
Indefinite Lived Intangible Assets Excluding Goodwill	3,089	3,080
Trade names | NBCUniversal Media, LLC [Member]	'	'
Indefinite Lived Intangible Assets Excluding Goodwill	3,089	3,080
FCC Licenses	'	'
Indefinite Lived Intangible Assets Excluding Goodwill	652	636
FCC Licenses | NBCUniversal Media, LLC [Member]	'	'
Indefinite Lived Intangible Assets Excluding Goodwill	652	636
Cable franchise renewal costs and contractual operating rights [Member]	'	'
Finite-lived intangible assets, gross carrying amount	1,360	1,257
Accumulated amortization	-745	-676
Weighted average original useful life	'10 years 0 months 0 days	'
Patents and other technology rights [Member]	'	'
Finite-lived intangible assets, gross carrying amount	361	350
Accumulated amortization	($307)	($283)
Weighted average original useful life	'9 years 0 months 0 days	'

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets (Amortization of Intangible Assets) (Details) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
Future amortization expense, 2014	$1,487
Future amortization expense, 2015	1,345
Future amortization expense, 2016	1,196
Future amortization expense, 2017	1,046
Future amortization expense, 2018	893
NBCUniversal Media, LLC [Member]	'
Future amortization expense, 2014	771
Future amortization expense, 2015	762
Future amortization expense, 2016	739
Future amortization expense, 2017	740
Future amortization expense, 2018	$734

LongTerm_Debt_Details

Long-Term Debt (Details)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2012

In Millions, unless otherwise specified

USD ($)

USD ($)

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Revolving bank credit facility [Member]

Comcast Commercial Paper Program

Senior notes with maturities of 5 years or less [Member]

Senior notes with maturities of 5 years or less [Member]

Senior notes with maturities of 5 years or less [Member]

Senior notes with maturities of 5 years or less [Member]

Senior notes with maturities between 6 and 10 years [Member]

Senior notes with maturities between 6 and 10 years [Member]

Senior notes with maturities between 6 and 10 years [Member]

Senior notes with maturities between 6 and 10 years [Member]

Senior notes with maturities greater than 10 years [Member]

Senior notes with maturities greater than 10 years [Member]

Senior notes with maturities greater than 10 years [Member]

Senior notes with maturities greater than 10 years [Member]

Other Including Capital Lease Obligations [Member]

Other Including Capital Lease Obligations [Member]

Other Including Capital Lease Obligations [Member]

Other Including Capital Lease Obligations [Member]

Notes 5.50% Due 2029 [Member]

Notes 5.50% Due 2029 [Member]

Notes 5.50% Due 2029 [Member]

Notes 5.50% Due 2029 [Member]

USD ($)

USD ($)

USD ($)

USD ($)

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

USD ($)

USD ($)

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

USD ($)

USD ($)

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

USD ($)

USD ($)

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

USD ($)

GBP (£)

USD ($)

GBP (£)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Commercial paper

$1,350

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Revolving credit facilities

1,250

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Senior notes

'

'

'

'

'

'

15,080

12,991

2,917

2,933

11,533

10,334

4,996

3,999

18,010

16,801

3,205

4,203

'

'

'

'

1,000

625

1,000

625

Other, including capital lease obligations

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

624

332

47

106

'

'

'

'

Total debt

47,847

40,458

11,165

11,241

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Less: current portion

3,280

2,376

906

10

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term debt

$44,567

$38,082

$10,259

$11,231

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Weighted average interest rate

4.80%

'

4.22%

'

1.17%

0.30%

4.72%

'

2.88%

'

4.56%

'

4.39%

'

5.97%

'

5.61%

'

'

'

'

'

'

'

'

'

Borrowing Margin Libor Based Borrowings

'

'

'

'

1.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

LongTerm_Debt_Debt_Maturities_

Long-Term Debt (Debt Maturities) (Details) (USD $)	Dec. 31, 2013
In Millions, unless otherwise specified
2014	$3,280
2015	3,420
2016	3,501
2017	2,557
2018	5,394
Thereafter	29,695
Weighted average interest rate	4.80%
NBCUniversal Media, LLC [Member]	'
2014	906
2015	1,032
2016	1,008
2017	2
2018	2
Thereafter	$8,215
Revolving bank credit facility [Member]	'
Weighted average interest rate	1.17%
Senior notes with maturities of 5 years or less [Member]	'
Weighted average interest rate	4.72%
Senior notes with maturities between 6 and 10 years [Member]	'
Weighted average interest rate	4.56%
Senior notes with maturities greater than 10 years [Member]	'
Weighted average interest rate	5.97%
2014	'
Weighted average interest rate	2.34%
2014 | NBCUniversal Media, LLC [Member]	'
Weighted average interest rate	2.12%
2015	'
Weighted average interest rate	5.90%
2015 | NBCUniversal Media, LLC [Member]	'
Weighted average interest rate	3.60%
2016	'
Weighted average interest rate	4.27%
2016 | NBCUniversal Media, LLC [Member]	'
Weighted average interest rate	2.88%
2017	'
Weighted average interest rate	6.98%
2017 | NBCUniversal Media, LLC [Member]	'
Weighted average interest rate	6.29%
2018	'
Weighted average interest rate	4.51%
2018 | NBCUniversal Media, LLC [Member]	'
Weighted average interest rate	6.30%
Thereafter [Member]	'
Weighted average interest rate	5.45%
Thereafter [Member] | NBCUniversal Media, LLC [Member]	'
Weighted average interest rate	4.87%

LongTerm_Debt_Narrative_Detail

Long-Term Debt (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Long-term Debt, Fair Value	$51,800,000,000	$47,700,000,000	'
Revolving credit facilities	1,250,000,000	'	'
Amounts available under revolving credit facilities	4,700,000,000	'	'
Repurchases and repayments of debt	2,444,000,000	2,881,000,000	3,216,000,000
Unused irrevocable standby letters of credit	515,000,000	'	'
Commercial paper prior borrowing capacity [Member]	'	'	'
Credit facility borrowing capacity	2,250,000,000	'	'
NBCUniversal Media, LLC [Member]	'	'	'
Long-term Debt, Fair Value	11,700,000,000	12,600,000,000	'
NBCUniversal Enterprise Senior Unsecured Debt Securities	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	4,000,000,000	'	'
Comcast Commercial Paper Program	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	750,000,000	'	'
NBCUniversal Enterprise Credit Facility	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	1,250,000,000	'	'
Amounts available under revolving credit facilities	100,000,000	'	'
Comcast And Comcast Cable Communications LLC [Member]	'	'	'
Debt Instrument, Maturity Date, Description	'June 2017	'	'
Credit facility borrowing capacity	6,250,000,000	'	'
Comcast And Comcast Cable Communications LLC [Member] | NBCUniversal Media, LLC [Member]	'	'	'
Debt Instrument, Maturity Date, Description	'June 2017	'	'
Credit facility borrowing capacity	6,250,000,000	'	'
Guarantee Obligations Current Principal Balance	31,000,000,000	'	'
NBCUniversal Enterprise [Member] | NBCUniversal Media, LLC [Member]	'	'	'
Principal amount	4,000,000,000	'	'
Preferred stock liquidition preference value	725,000,000	'	'
Senior 1.662% Notes Due 2018 [Member] | NBCUniversal Enterprise [Member]	'	'	'
Principal amount	1,100,000,000	'	'
Interest rate	1.66%	'	'
Debt Instrument, Maturity Date, Description	'2018	'	'
Senior 1.974% Notes Due 2019 [Member] | NBCUniversal Enterprise [Member]	'	'	'
Principal amount	1,500,000,000	'	'
Interest rate	1.97%	'	'
Debt Instrument, Maturity Date, Description	'2019	'	'
Floating Rate Senior Notes Due 2018 [Member] | NBCUniversal Enterprise [Member]	'	'	'
Principal amount	700,000,000	'	'
Debt Instrument, Maturity Date, Description	'2018	'	'
Spread above LIBOR offered rate	0.69%	'	'
Floating Rate Senior Notes Due 2016 [Member] | NBCUniversal Enterprise [Member]	'	'	'
Principal amount	700,000,000	'	'
Debt Instrument, Maturity Date, Description	'2016	'	'
Spread above LIBOR offered rate	0.54%	'	'
Other Long-Term Debt [Member]	'	'	'
Repurchases and repayments of debt	109,000,000	'	'
Notes 5.50% Due 2029 [Member]	'	'	'
Interest rate	5.50%	5.50%	'
Debt Instrument, Maturity Date, Description	'2029	'2029	'
Senior 2.850% Notes Due 2023 [Member]	'	'	'
Principal amount	750,000,000	'	'
Interest rate	2.85%	'	'
Debt Instrument, Maturity Date, Description	'2023	'	'
Senior 4.250% Notes Due 2033 [Member]	'	'	'
Principal amount	1,700,000,000	'	'
Interest rate	4.25%	'	'
Debt Instrument, Maturity Date, Description	'2033	'	'
Senior 4.500% Notes Due 2043 [Member]	'	'	'
Principal amount	500,000,000	'	'
Interest rate	4.50%	'	'
Debt Instrument, Maturity Date, Description	'2043	'	'
Current Year Borrowings [Member]	'	'	'
Principal amount	2,950,000,000	'	'
Prior NBCUniversal Credit Facility [Member]	'	'	'
Credit facility borrowing capacity	1,500,000,000	'	'
NBCUniversal Enterprise Credit Facility [Member]	'	'	'
Debt Instrument, Maturity Date, Description	'March 2018	'	'
Credit facility borrowing capacity	1,350,000,000	'	'
NBCUniversal Enterprise Credit Facility [Member] | NBCUniversal Media, LLC [Member]	'	'	'
Credit facility borrowing capacity	1,350,000,000	'	'
Senior 8.375% Notes Due 2013 [Member]	'	'	'
Interest rate	8.38%	'	'
Debt Instrument, Maturity Date, Description	'2013	'	'
Repurchases and repayments of debt	1,714,000,000	'	'
Senior 7.125% Notes Due 2013 [Member]	'	'	'
Interest rate	7.13%	'	'
Debt Instrument, Maturity Date, Description	'2013	'	'
Repurchases and repayments of debt	383,000,000	'	'
Senior 7.875% Notes Due 2013 [Member]	'	'	'
Interest rate	7.88%	'	'
Debt Instrument, Maturity Date, Description	'2013	'	'
Repurchases and repayments of debt	$238,000,000	'	'

LongTerm_Debt_Commercial_Paper

Long-Term Debt (Commercial Paper Program) (Details) (USD $)	Dec. 31, 2013
In Billions, unless otherwise specified
Commercial paper prior borrowing capacity [Member]	'
Credit facility borrowing capacity	$2.25
Revolving bank credit facility [Member] | Commercial paper new borrowing capacity [Member]	'
Credit facility borrowing capacity	$6.25

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Trading securities	$3,956	$4,027
Available-for-sale Securities	389	464
Interest rate swap agreements	110	210
Other [assets]	81	38
Fair value, assets measured on recurring basis, total	4,536	4,739
Derivative component of prepaid forward sale agreements and indexed debt instruments	2,816	2,305
Contractual obligations	747	1,055
Contingent consideration	684	587
Other [liabilities]	16	14
Fair value liabilities measured on recurring basis	4,263	3,961
Fair Value, Inputs, Level 1 [Member]	'	'
Trading securities	3,956	4,027
Available-for-sale Securities	260	367
Fair value, assets measured on recurring basis, total	4,216	4,394
Fair Value, Inputs, Level 2 [Member]	'	'
Available-for-sale Securities	118	76
Interest rate swap agreements	110	210
Other [assets]	80	36
Fair value, assets measured on recurring basis, total	308	322
Derivative component of prepaid forward sale agreements and indexed debt instruments	2,816	2,305
Other [liabilities]	16	14
Fair value liabilities measured on recurring basis	2,832	2,319
Fair Value, Inputs, Level 3 [Member]	'	'
Available-for-sale Securities	11	21
Other [assets]	1	2
Fair value, assets measured on recurring basis, total	12	23
Contractual obligations	747	1,055
Contingent consideration	684	587
Fair value liabilities measured on recurring basis	$1,431	$1,642

Fair_Value_Disclosure_Rollforw

Fair Value Disclosure Rollforward (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Discount rate used to determine fair value, minimum	5.00%	'
Discount rate used to determine fair value, maximum	13.00%	'
Nonrecurring fair value adjustments	$167	$161
NBCUniversal Media, LLC [Member]	'	'
Discount rate used to determine fair value, minimum	12.00%	'
Discount rate used to determine fair value, maximum	13.00%	'
Nonrecurring fair value adjustments	167	161
Contractual Obligations [Member]	'	'
Beginning balance	1,055	'
Fair value adjustments	158	'
Payments	-83	'
Liberty Media transaction	-383	'
Ending balance	747	'
Contractual Obligations [Member] | NBCUniversal Media, LLC [Member]	'	'
Beginning balance	1,055	'
Fair value adjustments	158	'
Payments	-83	'
Liberty Media transaction	-383	'
Ending balance	747	'
Contingent Consideration [Member]	'	'
Beginning balance	587	'
Fair value adjustments	106	'
Payments	-214	'
Redemption transaction	205	'
Ending balance	$684	'

Noncontrolling_Interests_Detai

Noncontrolling Interests (Details) (USD $)

3 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Mar. 19, 2013

Net income attributable to Parent

$1,913

$1,732

$1,734

$1,437

$1,518

$2,113

$1,348

$1,224

$6,816

$6,203

$4,160

'

Changes in equity resulting from net income attributable to Comcast Corporation and transfers from (to) noncontrolling interests

'

'

'

'

'

'

'

'

5,139

'

'

'

Remaining equity interest acquired

'

'

'

'

'

'

'

'

'

'

'

49.00%

Redemption Transaction [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Increase (decrease) in Comcast Corporation additional paid-in capital resulting from the purchase of noncontrolling interest

'

'

'

'

'

'

'

'

-1,651

'

'

'

Other Purchase [Member]

'

'

'

'

'

'

'

'

'

'

'

'

Increase (decrease) in Comcast Corporation additional paid-in capital resulting from the purchase of noncontrolling interest

'

'

'

'

'

'

'

'

($26)

'

'

'

Pension_Plans_and_Postretireme1

Pension Plans and Postretirement Benefits (Narrative) (Details) (USD $)

12 Months Ended

11 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

11 Months Ended

12 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Deferred Compensation Plans [Member]

Deferred Compensation Plans [Member]

Retirement Investment Plans [Member]

Retirement Investment Plans [Member]

Retirement Investment Plans [Member]

Retirement Investment Plans [Member]

Retirement Investment Plans [Member]

Retirement Investment Plans [Member]

NBCUniversal Qualified Pension Plan [Member]

NBCUniversal Qualified Pension Plan [Member]

NBCUniversal Qualified Pension Plan [Member]

NBCUniversal Multiemployer Contributions [Member]

NBCUniversal Multiemployer Contributions [Member]

NBCUniversal Multiemployer Contributions [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Multiemployer plan contributions

'

'

'

$42

$66

$53

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$66

$53

$42

Cash surrender value of life insurance policies

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

565

478

'

'

'

'

'

'

'

'

'

'

'

'

Expenses related to retirement investment plans

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

324

246

226

70

152

85

'

'

'

'

'

'

Severance costs

160

155

128

89

116

90

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Multiemployer Plans Funded Status

'

'

'

'

'At least 80 percent

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'At least 80 percent

'

'

Contribution to fully fund and settle plan

'

'

'

'

'

'

'

'

'

'

'

'

55

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Reclassification adjustment from accumulated other comprehensive income before tax

'

'

'

'

'

'

'

'

'

'

'

'

74

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Plan funded status

'

'

'

'

'

'

-633

-703

-618

-158

-177

-161

-278

-402

-462

-278

-329

-427

'

'

'

'

'

'

'

'

8

8

'

'

'

'

Benefit obligations in excess of plan assets

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$43

$50

'

'

'

Pension_Plans_and_Postretireme2

Pension Plans and Postretirement Benefits (Information On Our Pension Benefit Plans) (Details) (USD $)

12 Months Ended

11 Months Ended

12 Months Ended

12 Months Ended

11 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Pension Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

Postretirement Benefits [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Minimum [Member]

Maximum [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Benefit obligation

$498

$805

$638

$427

$498

$546

'

'

'

'

'

'

'

'

'

'

'

'

$633

$703

$618

$161

$158

$177

'

'

Fair value of plan assets

220

403

176

'

220

217

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Plan funded status and recorded benefit obligation

-278

-402

-462

-427

-278

-329

'

'

'

'

'

'

'

'

'

'

'

'

-633

-703

-618

-161

-158

-177

'

'

Portion of benefit obligation not yet recognized in benefits expense

-3

151

137

71

-3

53

'

'

'

'

'

'

'

'

'

'

'

'

-110

17

-17

-13

-44

-11

'

'

Benefits expense

$12

$163

$117

$111

$12

$142

'

'

'

'

'

'

'

'

'

'

'

'

$65

$60

$47

$14

$14

$15

'

'

Discount rate

'

'

'

'

'

'

4.50%

3.25%

4.75%

4.50%

3.75%

4.75%

5.25%

4.25%

5.25%

5.25%

4.25%

5.25%

'

4.25%

4.75%

4.75%

5.25%

4.25%

5.00%

5.25%

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets

5.00%

5.00%

6.50%

'

5.00%

5.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Pension_Plans_and_Postretireme3

Pension Plans and Postretirement Benefits (Components of Benefits Expense)(Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Service cost	'	139	99
Pension Benefits [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Expected return on plan assets	5.00%	5.00%	6.50%
Pension Benefits [Member] | NBCUniversal Media, LLC [Member]	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'
Service cost	'	134	99
Expected return on plan assets	5.00%	5.00%	'

Pension_Plans_and_Postretireme4

Pension Plans and Postretirement Benefits (Deferred Compensation Plans) (Details) (USD $)	11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	Deferred Compensation Plans [Member]	Deferred Compensation Plans [Member]	Deferred Compensation Plans [Member]
Benefit obligation	$114	$250	$163	$1,434	$1,247	$1,059
Interest expense	$10	$18	$11	$128	$107	$99

Pension_Plans_and_Postretireme5

Pension Plans and Postretirement Benefits (Benefit Obligation and Expense for Our Split-Dollar Life Insurance Agreements) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Benefit obligation	$212	$202	$169
Other operating and administrative expenses	$50	$58	$27

Equity_Narrative_Details

Equity (Narrative) (Details) (USD $)	12 Months Ended				1 Months Ended	11 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Feb. 28, 2014	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Jan. 28, 2011	Dec. 31, 2013	Dec. 31, 2013
				Existing Authorization [Member]	New Authorization [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	Class A Common Stock [Member]	Class B Common Stock [Member]
									Distribution To Ge Prior To Close Of Joint Venture Transaction [Member]
Voting power	'	'	'	'	'	'	'	'	'	66.67%	33.33%
Number of votes entitled of each class B common stock	15	'	'	'	'	'	'	'	'	'	'
Share repurchase authorization	'	'	'	$6,500,000,000	$7,500,000,000	'	'	'	'	'	'
Availability remaining under share repurchase program	'	'	'	1,500,000,000	'	'	'	'	'	'	'
Dividends paid	1,964,000,000	1,608,000,000	1,187,000,000	'	'	'	'	'	7,400,000,000	'	'
Redemption Transaction Distribution	'	'	'	'	'	'	3,200,000,000	'	'	'	'
Distributions to member	'	'	'	'	'	$244,000,000	$1,400,000,000	$964,000,000	'	'	'

Equity_Changes_in_Common_Stock

Equity (Changes in Common Stock) (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Repurchases and retirements of common stock	49,000,000	96,000,000	95,000,000
Class A Common Stock [Member]	'	'	'
Common Stock, Shares, Outstanding, Beginning Balance	2,122,278,635	2,095,000,000	2,072,000,000
Stock compensation plans	14,000,000	24,000,000	20,000,000
Repurchases and retirements of common stock	0	0	0
Employee stock purchase plan	2,000,000	3,000,000	3,000,000
Common Stock, Shares, Outstanding, Ending Balance	2,138,075,133	2,122,278,635	2,095,000,000
ClassA Special Common Stock [Member]	'	'	'
Common Stock, Shares, Outstanding, Beginning Balance	507,769,463	601,000,000	695,000,000
Stock compensation plans	0	3,000,000	1,000,000
Repurchases and retirements of common stock	-49,000,000	-96,000,000	-95,000,000
Employee stock purchase plan	0	0	0
Common Stock, Shares, Outstanding, Ending Balance	459,030,180	507,769,463	601,000,000
Class B Common Stock [Member]	'	'	'
Common Stock, Shares, Outstanding, Beginning Balance	9,444,375	9,000,000	9,000,000
Stock compensation plans	0	0	0
Repurchases and retirements of common stock	0	0	0
Employee stock purchase plan	0	0	0
Common Stock, Shares, Outstanding, Ending Balance	9,444,375	9,444,375	9,000,000

Equity_Aggregate_Share_Repurch

Equity (Aggregate Share Repurchases) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Equity	'	'	'
Cash consideration	$2,000	$3,000	$2,141
Shares repurchased	49	96	95

Equity_Components_of_Accumulat

Equity (Components of Accumulated Other Comprehensive Income (Loss)) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Unrealized gains (losses) on marketable securities	$67	$182
Deferred gains (losses) on cash flow hedges	-45	-67
Unrecognized gains (losses) on employee benefit obligations	71	-95
Cumulative translation adjustments	-37	-5
Accumulated other comprehensive income (loss), net of deferred taxes	56	15
NBCUniversal Media, LLC [Member]	'	'
Deferred gains (losses) on cash flow hedges	-5	'
Unrecognized gains (losses) on employee benefit obligations	45	-50
Cumulative translation adjustments	-56	-15
Accumulated other comprehensive income (loss), net of deferred taxes	($16)	($65)

ShareBased_Compensation_Narrat

Share-Based Compensation (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Stock Options [Member]	'
Unrecognized pretax compensation expense on nonvested awards	$318
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years)	'1 year 10 months 24 days
Stock Options [Member] | NBCUniversal Media, LLC [Member]	'
Unrecognized pretax compensation expense on nonvested awards	35
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years)	'2 years 2 months 12 days
Restricted Share Units [Member]	'
Unrecognized pretax compensation expense on nonvested awards	380
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years)	'1 year 8 months 12 days
Restricted Share Units [Member] | NBCUniversal Media, LLC [Member]	'
Unrecognized pretax compensation expense on nonvested awards	$98
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years)	'1 year 8 months 12 days

ShareBased_Compensation_Recogn

Share-Based Compensation (Recognized Share-Based Compensation Expense) (Details) (USD $)

12 Months Ended

11 Months Ended

12 Months Ended

11 Months Ended

12 Months Ended

11 Months Ended

12 Months Ended

11 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Stock Options [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Restricted Share Units [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

Employee Stock Purchase Plan [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Recognized share-based compensation expense

$334

$301

$278

$33

$62

$47

$139

$131

$116

$13

$15

$15

$175

$154

$149

$18

$42

$28

$20

$16

$13

$2

$5

$4

ShareBased_Compensation_Stock_

Share-Based Compensation (Stock Options and Restricted Share Units) (Details) (USD $)	12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock options granted	18	'	'
Weighted-average exercise price, granted	$41.22	'	'
Stock options outstanding	104	'	'
Weighted-average exercise price, outstanding	$25.49	'	'
RSUs granted	7	'	'
Weighted average fair value of RSUs at grant date	$38.28	$27.80	$22.78
Nonvested restricted share units	26	'	'
Weighted-average fair value at grant date of nonvested RSUs	$25.38	'	'
Net Settled Options [Member]	'	'	'
Stock options outstanding	102	'	'

ShareBased_Compensation_Restri

Share-Based Compensation (Restricted Share Units and Stock Option Fair Value) (Details) (USD $)	12 Months Ended			11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Weighted average fair value of RSUs	$38.28	$27.80	$22.78	$21.75	$37.79	$27.51
Fair value of stock options	$8.80	$7.38	$6.96	$6.77	$8.86	$7.42
Dividend yield	1.90%	2.20%	1.80%	1.80%	1.90%	2.20%
Expected volatility	25.00%	29.00%	28.10%	28.50%	25.20%	29.00%
Risk-free interest rate	1.30%	1.70%	2.80%	2.60%	1.30%	1.70%
Expected option life (in years)	'7 years 0 months 0 days	'7 years 0 months 0 days	'7 years 0 months 0 days	'7 years 0 months 0 days	'7 years 0 months 0 days	'7 years 0 months 0 days

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Foreign income before taxes	$524,000,000	$434,000,000	$476,000,000
Liability for uncertain tax positions, noncurrent	1,700,000,000	'	'
Unrecognized tax benefits that would impact effective tax rate	980,000,000	'	'
Unrecognized tax benefits, interest on income taxes accrued	780,000,000	721,000,000	'
Deferred income taxes	31,935,000,000	30,110,000,000	'
Franchise Rights [Member]	'	'	'
Net deferred tax liability, franchise rights	23,000,000,000	'	'
NBCUniversal [Member]	'	'	'
Foreign income before taxes	'	434,000,000	'
Uncertain Tax Positions Indemnified By GE [Member]	'	'	'
Liability for uncertain tax positions, noncurrent	283,000,000	'	'
Unrecognized tax benefits, interest on income taxes accrued	42,000,000	11,000,000	'
Redemption Transaction [Member]	'	'	'
Deferred income taxes	1,600,000,000	'	'
Other Comprehensive Income (Loss) [Member]	'	'	'
Income tax effects allocated directly to equity, other	25,000,000	'	'
Share Based Compensation [Member]	'	'	'
Income tax effects allocated directly to equity, other	244,000,000	164,000,000	38,000,000
Domestic Tax Authority	'	'	'
Operating loss carryforwards	176,000,000	'	'
Operating loss carryforwards expiration dates	31-Dec-33	'	'
Foreign Tax Authority	'	'	'
Operating loss carryforwards	$279,000,000	'	'
Operating loss carryforwards expiration dates	31-Dec-23	'	'

Income_Taxes_Components_of_Inc

Income Taxes (Components of Income Tax Expense) (Details) (USD $)	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Federal	$3,183	$3,004	$1,480	'	'	'	'
State	581	432	359	'	'	'	'
Foreign	200	169	153	'	53	77	69
Current income tax expense (benefit)	3,964	3,605	1,992	'	'	'	'
Federal	-76	160	658	'	'	'	'
Foreign	-16	19	29	'	29	-16	16
State	108	-40	371	'	'	'	'
Deferred income tax expense (benefit)	16	139	1,058	'	'	'	'
U.S. domestic tax expense	'	'	'	'	3	22	9
Withholding tax expense	'	'	'	'	100	123	103
Income tax expense	$3,980	$3,744	$3,050	($4)	$185	$206	$197

Income_Taxes_Federal_Statutory

Income Taxes (Federal Statutory) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Federal tax at statutory rate	$3,890	$4,063	$2,872
State income taxes, net of federal benefit	319	178	354
Foreign income taxes, net of federal credit	15	92	89
Nontaxable income attributable to noncontrolling interests	-103	-620	-410
Other adjustments	-313	-106	2
Income tax expense	3,980	3,744	3,050
Uncertain And Effectively Settled Tax Positions, Net [Member]	'	'	'
Other adjustments	58	114	77
Accrued Interest On Uncertain And Effectively Settled Tax Positions Net [Member]	'	'	'
Other adjustments	$114	$23	$66

Income_Taxes_Components_of_Net

Income Taxes (Components of Net Deferred Tax Liability) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Net operating loss carryforwards	$495	$491
Differences between book and tax basis of long-term debt	117	109
Nondeductible accruals and other	3,588	1,771
Less: Valuation allowance	405	355
Total deferred tax assets	3,795	2,016
Total deferred tax liabilities	35,494	32,033
Net deferred tax liability	31,699	30,017
Property And Equipment And Intangible Assets [Member]	'	'
Deferred tax liabilities, other	34,044	29,185
Investments [Member]	'	'
Deferred tax liabilities, other	473	848
Indexed Debt Securities [Member]	'	'
Deferred tax liabilities, other	610	587
Foreign Subsidiaries And Undistributed Foreign Earnings [Member]	'	'
Deferred tax liabilities, other	367	'
Differences Between Book And Tax Outside Basis Of NBCuniversal [Member] | NBCUniversal [Member]	'	'
Deferred tax liabilities, other	'	$1,413

Income_Taxes_Reconciliation_of

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Abstract]	'	'	'
Beginning balance	$1,573	$1,435	$1,251
Additions based on tax positions related to the current year	90	154	87
Additions based on tax positions related to prior years	201	79	75
Additions from acquired subsidiaries	268	0	57
Reductions for tax positions of prior years	-141	-60	-22
Reductions due to expiration of statutes of limitations	-3	-3	-5
Settlements with taxing authorities	-287	-32	-8
Ending balance	$1,701	$1,573	$1,435

Supplemental_Financial_Informa2

Supplemental Financial Information (Receivables)(Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Receivables, gross	$6,972	$6,026
Less: Allowance for returns and customer incentives	375	307
Less: Allowance for doubtful accounts	221	198
Receivables, net	6,376	5,521
Noncurrent receivables, net	488	641
NBCUniversal Media, LLC [Member]	'	'
Receivables, gross	5,348	4,381
Less: Allowance for returns and customer incentives	372	307
Less: Allowance for doubtful accounts	65	46
Receivables, net	4,911	4,028
Noncurrent receivables, net	$488	$641

Supplemental_Financial_Informa3

Supplemental Financial Information (Cash Payments for Interest and Income Taxes)(Details) (USD $)	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Interest	$2,355	$2,314	$2,441	$1	$444	$462	$461
Income taxes	$3,946	$2,841	$1,626	$493	$161	$205	$169

Supplemental_Financial_Informa4

Supplemental Financial Information (Other Cash Flow Information) (Details) (USD $)

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2013

Dec. 31, 2012

Jan. 28, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Jan. 28, 2011

Dec. 31, 2010

In Millions, unless otherwise specified

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Successor [Member]

Successor [Member]

Successor [Member]

Successor [Member]

Predecessor [Member]

Predecessor [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Cash and cash equivalents, beginning of year

$1,718

$10,951

$1,620

$5,984

$967

$5,921

'

$967

$5,921

$808

$508

$470

$1,084

Comcast Content Business Contributed Cash Balances

'

'

'

'

'

'

38

'

'

'

'

'

'

Cash and cash equivalents, end of year

$1,718

$10,951

$1,620

$5,984

$967

$5,921

'

$967

$5,921

$808

$508

$470

$1,084

Supplemental_Financial_Informa5

Supplemental Financial Information (Noncash Investing and Financing Activities)(Details) (USD $)	12 Months Ended					11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Mar. 19, 2013	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
						NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Enterprise Credit Facility	NBCUniversal Enterprise Senior Unsecured Debt Securities	NBCUniversal Enterprise Preferred Stock
Remaining equity interest acquired	'	'	'	49.00%	'	'	'	'	'	'	'
Purchase of NBCUniversal noncontrolling interest	$16,700,000,000	'	'	'	'	'	'	'	'	'	'
Consideration transferred related to the Redemption Transaction and purchase of certain properties	'	'	'	'	'	'	'	'	1,250,000,000	4,000,000,000	725,000,000
Total noncash consideration transferred related to the Redemption Transaction	6,000,000,000	'	'	'	'	'	'	'	'	'	'
Dividends payable, amount	509,000,000	430,000,000	305,000,000	'	'	'	'	'	'	'	'
Dividends payable, amount per share	$0.20	$0.16	$0.11	'	'	'	'	'	'	'	'
Capital expenditures incurred but not yet paid	872,000,000	757,000,000	1,000,000,000	'	'	'	'	'	'	'	'
Noncash or Part Noncash Acquisition, Fixed Assets Acquired	'	85,000,000	'	'	'	'	'	85,000,000	'	'	'
Fair Value Equity Securities Settlement	1,400,000,000	'	'	'	'	'	'	'	'	'	'
Ownership percentage	'	'	51.00%	'	51.00%	'	'	'	'	'	'
Percentage of Comcast Content Business contributed	'	'	49.00%	'	'	'	'	'	'	'	'
Capital expenditures and cash paid for intangible assets incurred but not yet paid	'	'	'	'	'	$339,000,000	$306,000,000	'	'	'	'

Receivables_Monetization_Narra

Receivables Monetization (Narrative)(Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Monetization programs payable	'	$882
Payments to third-party banks related to the termination of the monetization programs	1,442	'
Accounts Receivables Monetized And Uncollected At Program Termination Date	1,078	'
Cash Receipts Collected And Unremitted At Program Termination Date	364	'
NBCUniversal Media, LLC [Member]	'	'
Monetization programs payable	'	882
Payments to third-party banks related to the termination of the monetization programs	1,442	'
Accounts Receivables Monetized And Uncollected At Program Termination Date	1,078	'
Cash Receipts Collected And Unremitted At Program Termination Date	$364	'

Receivables_Monetization_Effec

Receivables Monetization (Effect on Income From Receivables Monetization and Cash Flows on Transfers)(Details) (USD $)	12 Months Ended		11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2012
			NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Net cash proceeds (payments) on transfers	($86)	($237)	($237)	($86)

Receivables_Monetization_Recei

Receivables Monetization (Receivables Monetized and Deferred Consideration)(Details) (USD $)	Dec. 31, 2012
In Millions, unless otherwise specified
Monetized receivables sold	$791
Deferred consideration	274
NBCUniversal Media, LLC [Member]	'
Monetized receivables sold	791
Deferred consideration	$274

Commitments_and_Contingencies_1

Commitments and Contingencies (Narrative) (Details)	Dec. 31, 2013
	numberofemployees
Number of employees covered under collective bargaining agreements	7,200
Percentage of employees covered under collective bargaining agreements that have expired or are scheduled to expire during 2014	19.00%
NBCUniversal Media, LLC [Member]	'
Number of employees covered under collective bargaining agreements	7,200
Percentage of employees covered under collective bargaining agreements that have expired or are scheduled to expire during 2014	19.00%

Commitments_and_Contingencies_2

Commitments and Contingencies (Minimum Annual Commitments under the Programming License Agreements and Operating Leases) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013
Programming and talent commitments future minimum payments, 2014	$4,899
Programming and talent commitments future minimum payments, 2015	3,190
Programming and talent commitments future minimum payments, 2016	4,039
Programming and talent commitments future minimum payments, 2017	2,755
Programming and talent commitments future minimum payments, 2018	3,672
Programming and talent commitments future minimum payments, thereafter	20,522
Operating leases future minimum payments, 2014	385
Operating leases future minimum payments, 2015	335
Operating leases future minimum payments, 2016	293
Operating leases future minimum payments, 2017	252
Operating leases future minimum payments, 2018	206
Operating leases future minimum payments, thereafter	673
NBCUniversal Media, LLC [Member]	'
Programming and talent commitments future minimum payments, 2014	4,876
Programming and talent commitments future minimum payments, 2015	3,182
Programming and talent commitments future minimum payments, 2016	4,035
Programming and talent commitments future minimum payments, 2017	2,755
Programming and talent commitments future minimum payments, 2018	3,672
Programming and talent commitments future minimum payments, thereafter	20,522
Operating leases future minimum payments, 2014	164
Operating leases future minimum payments, 2015	133
Operating leases future minimum payments, 2016	117
Operating leases future minimum payments, 2017	107
Operating leases future minimum payments, 2018	92
Operating leases future minimum payments, thereafter	$365

Commitments_and_Contingencies_3

Commitments and Contingencies (Rental expense) (Details) (USD $)	12 Months Ended			1 Months Ended	11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 28, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Rent expense	$616	$688	$570	$18	$267	$250	$317

Financial_Data_by_Business_Seg2

Financial Data by Business Segment (Details) (USD $)

3 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

1 Months Ended

11 Months Ended

12 Months Ended

In Millions, unless otherwise specified

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Jan. 28, 2011

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2012

Dec. 31, 2012

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Non U S Customers [Member]

Non U S Customers [Member]

Non U S Customers [Member]

Non U S Customers [Member]

Non U S Customers [Member]

Non U S Customers [Member]

Non U S Customers [Member]

United States [Member]

United States [Member]

United States [Member]

United States [Member]

Cable Communications [Member]

Cable Communications [Member]

Cable Communications [Member]

Cable Communications [Member]

Cable Communications [Member]

Cable Communications [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Cable Networks [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Broadcast Television [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Filmed Entertainment [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Theme Parks [Member]

Headquarters And Other [Member]

Headquarters And Other [Member]

Headquarters And Other [Member]

Headquarters And Other [Member]

Headquarters And Other [Member]

Headquarters And Other [Member]

Headquarters And Other [Member]

NBCUniversal Eliminations [Member]

NBCUniversal Eliminations [Member]

NBCUniversal Eliminations [Member]

NBCUniversal Eliminations [Member]

NBCUniversal Eliminations [Member]

NBCUniversal Eliminations [Member]

NBCUniversal Eliminations [Member]

NBCUniversal [Member]

NBCUniversal [Member]

NBCUniversal [Member]

Corporate and Other [Member]

Corporate and Other [Member]

Corporate and Other [Member]

Eliminations [Member]

Eliminations [Member]

Eliminations [Member]

Cable Communications Segment Revenue Percentage-Video [Member]

Cable Communications Segment Revenue Percentage-Video [Member]

Cable Communications Segment Revenue Percentage-Video [Member]

Cable Communications Segment Revenue Percentage - High-speed Internet [Member]

Cable Communications Segment Revenue Percentage - High-speed Internet [Member]

Cable Communications Segment Revenue Percentage - High-speed Internet [Member]

Cable Communications Segment Revenue Percentage- Voice [Member]

Cable Communications Segment Revenue Percentage- Voice [Member]

Cable Communications Segment Revenue Percentage- Voice [Member]

Cable Communications Segment Revenue Percentage- Advertising [Member]

Cable Communications Segment Revenue Percentage- Advertising [Member]

Cable Communications Segment Revenue Percentage- Advertising [Member]

Cable Communications Segment Revenue Percentage- Business Services [Member]

Cable Communications Segment Revenue Percentage- Business Services [Member]

Cable Communications Segment Revenue Percentage- Business Services [Member]

Cable Communications Segment Revenue Percentage- Other [Member]

Cable Communications Segment Revenue Percentage- Other [Member]

Cable Communications Segment Revenue Percentage- Other [Member]

Cable Communications Segment Revenue Percentage- Franchise and other regulatory fees [Member]

Cable Communications Segment Revenue Percentage- Franchise and other regulatory fees [Member]

Cable Communications Segment Revenue Percentage- Franchise and other regulatory fees [Member]

London 2012 Olympics [Member]

London 2012 Olympics [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Corporate [Member]

Corporate [Member]

Corporate [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

NBCUniversal Media, LLC [Member]

Corporate [Member]

Corporate [Member]

Corporate [Member]

Intersegment Eliminations [Member]

Intersegment Eliminations [Member]

Intersegment Eliminations [Member]

NBCUniversal Media, LLC [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Operating Segments [Member]

Corporate [Member]

Corporate [Member]

Corporate [Member]

Corporate [Member]

Intersegment Eliminations [Member]

Intersegment Eliminations [Member]

Intersegment Eliminations [Member]

Intersegment Eliminations [Member]

Revenue

$16,926

$16,151

$16,270

$15,310

$15,937

$16,544

$15,211

$14,878

$64,657

$62,570

$55,842

$1,206

$19,028

$23,650

$23,812

$4,800

$4,500

$4,100

$271

$4,101

$4,763

$4,464

$935

$14,927

$18,887

$19,348

'

'

'

$41,836

$39,604

$37,226

$9,201

$8,727

$8,061

$385

$7,829

$9,201

$8,727

$7,120

$8,200

$5,982

$468

$5,982

$7,120

$8,200

$5,452

$5,159

$4,239

$353

$4,239

$5,452

$5,159

$2,235

$2,085

$1,874

$115

$1,874

$2,235

$2,085

$31

$43

$45

$5

$45

$31

$43

($389)

($402)

($941)

($120)

($941)

($389)

($402)

$23,650

$23,812

$19,260

$600

$498

$558

($1,429)

($1,344)

($1,202)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Operating income (loss) before depreciation and amortization

'

'

'

'

'

'

'

'

21,434

19,977

18,357

35

3,396

4,732

4,107

'

'

'

'

'

'

'

'

'

'

'

'

'

'

17,205

16,255

15,288

3,501

3,303

3,199

145

3,133

3,501

3,303

345

358

124

-18

124

345

358

483

79

27

1

27

483

79

1,004

953

830

37

830

1,004

953

-588

-603

-484

-99

-484

-588

-603

-13

17

-234

-31

-234

-13

17

4,732

4,107

3,462

-489

-376

-416

-14

-9

23

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

120

120

Depreciation and amortization

'

'

'

'

'

'

'

'

7,871

7,798

7,636

27

1,113

1,411

1,326

'

'

'

'

'

'

'

'

'

'

'

'

'

'

6,394

6,405

6,395

734

735

712

3

694

734

735

98

97

85

6

85

98

97

15

16

19

2

19

15

16

300

268

201

14

201

300

268

264

210

168

2

114

264

210

'

'

-53

'

'

'

'

1,411

1,326

1,132

66

67

93

'

'

16

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Operating income (loss)

3,647

3,414

3,435

3,067

3,294

3,048

3,079

2,758

13,563

12,179

10,721

8

2,283

3,321

2,781

'

'

'

'

'

'

'

'

'

'

'

'

'

'

10,811

9,850

8,893

2,767

2,568

2,487

142

2,439

2,767

2,568

247

261

39

-24

39

247

261

468

63

8

-1

8

468

63

704

685

629

23

629

704

685

-852

-813

-652

-101

-598

-852

-813

-13

17

-181

-31

-234

-13

17

3,321

2,781

2,330

-555

-443

-509

-14

-9

7

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Assets

158,813

'

'

'

164,971

'

'

'

158,813

164,971

'

'

'

51,739

54,462

'

'

'

'

'

'

'

'

'

'

'

'

'

'

132,082

127,044

'

29,413

29,636

'

'

'

29,413

29,636

6,723

6,414

'

'

'

6,723

6,414

3,549

3,769

'

'

'

3,549

3,769

6,608

6,266

'

'

'

6,608

6,266

6,002

8,938

'

'

'

6,002

8,938

-556

-561

'

'

'

-556

-561

51,739

54,462

'

8,152

6,000

'

-33,160

-22,535

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Capital expenditures

'

'

'

'

'

'

'

'

6,596

5,714

5,307

16

432

1,160

763

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,403

4,921

4,806

67

150

48

1

46

67

150

65

65

61

1

61

65

65

9

7

6

1

6

9

7

580

272

154

9

154

580

272

439

269

165

4

165

439

269

'

'

'

'

'

'

'

1,160

763

434

33

30

67

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cable segment revenue types as percentage of total cable revenue

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

100.00%

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

49.10%

50.40%

52.30%

24.70%

24.10%

23.50%

8.70%

9.00%

9.40%

5.20%

5.80%

5.40%

7.70%

6.50%

5.20%

4.60%

4.20%

4.20%

2.80%

2.80%

2.80%

'

'

Liability associated with unfavorable contract

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$237

$237

Quarterly_Financial_Informatio2

Quarterly Financial Information (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information	'	'	'	'	'	'	'	'	'	'	'
Revenue	$16,926	$16,151	$16,270	$15,310	$15,937	$16,544	$15,211	$14,878	$64,657	$62,570	$55,842
Operating income	3,647	3,414	3,435	3,067	3,294	3,048	3,079	2,758	13,563	12,179	10,721
Net income attributable to Parent	$1,913	$1,732	$1,734	$1,437	$1,518	$2,113	$1,348	$1,224	$6,816	$6,203	$4,160
Basic earnings per common share attributable to Comcast Corporation shareholders	$0.73	$0.66	$0.66	$0.55	$0.57	$0.79	$0.50	$0.45	$2.60	$2.32	$1.51
Diluted earnings per common share attributable to Comcast Corporation shareholders	$0.72	$0.65	$0.65	$0.54	$0.56	$0.78	$0.50	$0.45	$2.56	$2.28	$1.50
Dividends declared per common share	$0.20	$0.20	$0.20	$0.20	$0.16	$0.16	$0.16	$0.16	$0.78	$0.65	$0.45

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013
Holding company ownership in subsidiaries	100.00%
Comcast Holdings' ZONES due October 2029 [Member]	'
Principal amount of debt securities subject to guarantee	185,000,000
Comcast Holdings' ZONES due November 2029 [Member]	'
Principal amount of debt securities not subject to guarantee	62,000,000
Guarantor Subsidiaries [Member]	'
Principal amount of debt securities subject to guarantee	30,900,000,000
Maturing In Next Five Years [Member]	'
Principal amount of debt securities subject to guarantee	11,000,000,000
Comcast And Comcast Cable Communications LLC [Member]	'
Credit facility borrowing capacity	6,250,000,000
NBCUniversal Enterprise [Member]	'
Credit facility borrowing capacity	1,350,000,000
Principal amount of debt securities subject to guarantee	4,000,000,000

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheet) (Details) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
In Millions, unless otherwise specified
Cash and cash equivalents	$1,718	$10,951	$1,620	$5,984
Investments [Current]	3,573	1,464	'	'
Receivables, net	6,376	5,521	'	'
Programming rights	928	909	'	'
Other current assets	1,480	1,146	'	'
Total current assets	14,075	19,991	'	'
Film and television costs	4,994	5,054	'	'
Investments	3,770	6,325	'	'
Property and equipment, net	29,840	27,232	'	'
Franchise rights	59,364	59,364	'	'
Goodwill	27,098	26,985	26,874	'
Other intangible assets, net	17,329	17,840	'	'
Other noncurrent assets, net	2,343	2,180	'	'
Total assets	158,813	164,971	'	'
Accounts payable and accrued expenses related to trade creditors	5,528	6,206	'	'
Accrued participations and residuals	1,239	1,350	'	'
Accrued expenses and other current liabilities [condensed]	8,865	6,782	'	'
Current portion of long-term debt	3,280	2,376	'	'
Total current liabilities	18,912	16,714	'	'
Long-term debt, less current portion	44,567	38,082	'	'
Deferred income taxes	31,935	30,110	'	'
Other noncurrent liabilities	11,384	13,271	'	'
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	957	16,998	'	'
Common stock	30	31	'	'
Other shareholders' equity	50,664	49,325	'	'
Total Parent Company equity	50,694	49,356	'	'
Noncontrolling interests	364	440	'	'
Total equity	51,058	49,796	47,655	44,434
Total liabilities and equity	158,813	164,971	'	'
Comcast [Member]	'	'	'	'
Other current assets	237	233	'	'
Total current assets	237	233	'	'
Investments	11	'	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	79,956	74,227	'	'
Property and equipment, net	220	242	'	'
Other intangible assets, net	11	12	'	'
Other noncurrent assets, net	1,078	1,130	'	'
Total assets	81,513	75,844	'	'
Accounts payable and accrued expenses related to trade creditors	8	8	'	'
Accrued expenses and other current liabilities [condensed]	1,371	1,290	'	'
Current portion of long-term debt	2,351	'	'	'
Total current liabilities	3,730	1,298	'	'
Long-term debt, less current portion	25,170	23,306	'	'
Deferred income taxes	'	0	'	'
Other noncurrent liabilities	1,919	1,884	'	'
Common stock	30	31	'	'
Other shareholders' equity	50,664	49,325	'	'
Total Parent Company equity	50,694	49,356	'	'
Total equity	50,694	49,356	'	'
Total liabilities and equity	81,513	75,844	'	'
Comcast Holdings [Member]	'	'	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	97,429	87,630	'	'
Other noncurrent assets, net	145	147	'	'
Total assets	97,574	87,777	'	'
Accrued expenses and other current liabilities [condensed]	266	275	'	'
Total current liabilities	266	275	'	'
Long-term debt, less current portion	132	113	'	'
Deferred income taxes	777	754	'	'
Other shareholders' equity	96,399	86,635	'	'
Total Parent Company equity	96,399	86,635	'	'
Total equity	96,399	86,635	'	'
Total liabilities and equity	97,574	87,777	'	'
CCCL Parent [Member]	'	'	'	'
Other current assets	'	14	'	'
Total current assets	'	14	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	102,673	96,853	'	'
Other noncurrent assets, net	'	1	'	'
Total assets	102,673	96,868	'	'
Accrued expenses and other current liabilities [condensed]	180	210	'	'
Current portion of long-term debt	'	2,105	'	'
Total current liabilities	180	2,315	'	'
Long-term debt, less current portion	1,827	1,827	'	'
Other shareholders' equity	100,666	92,726	'	'
Total Parent Company equity	100,666	92,726	'	'
Total equity	100,666	92,726	'	'
Total liabilities and equity	102,673	96,868	'	'
Combined CCHMO Parents [Member]	'	'	'	'
Other current assets	'	4	'	'
Total current assets	'	4	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	54,724	50,242	'	'
Total assets	54,724	50,246	'	'
Accrued expenses and other current liabilities [condensed]	47	54	'	'
Current portion of long-term debt	'	241	'	'
Total current liabilities	47	295	'	'
Long-term debt, less current portion	1,505	1,512	'	'
Other shareholders' equity	53,172	48,439	'	'
Total Parent Company equity	53,172	48,439	'	'
Total equity	53,172	48,439	'	'
Total liabilities and equity	54,724	50,246	'	'
NBCUniversal Media Parent [Member]	'	'	'	'
Cash and cash equivalents	336	5,129	238	'
Receivables, net	'	3	'	'
Other current assets	35	51	'	'
Total current assets	371	5,183	'	'
Investments	374	529	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	40,644	38,464	'	'
Other noncurrent assets, net	103	152	'	'
Total assets	41,492	44,328	'	'
Accrued expenses and other current liabilities [condensed]	323	263	'	'
Current portion of long-term debt	903	7	'	'
Total current liabilities	1,226	270	'	'
Long-term debt, less current portion	10,236	11,219	'	'
Deferred income taxes	59	78	'	'
Other noncurrent liabilities	931	926	'	'
Other shareholders' equity	29,040	31,835	'	'
Total Parent Company equity	29,040	31,835	'	'
Total equity	29,040	31,835	'	'
Total liabilities and equity	41,492	44,328	'	'
Comcast Non-Guarantor Subsidiaries [Member]	'	'	'	'
Cash and cash equivalents	1,382	5,822	1,382	5,984
Investments [Current]	3,573	1,464	'	'
Receivables, net	6,376	5,518	'	'
Programming rights	928	909	'	'
Other current assets	1,208	844	'	'
Total current assets	13,467	14,557	'	'
Film and television costs	4,994	5,054	'	'
Investments	3,385	5,796	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	85,164	73,298	'	'
Property and equipment, net	29,620	26,990	'	'
Franchise rights	59,364	59,364	'	'
Goodwill	27,098	26,985	'	'
Other intangible assets, net	17,318	17,828	'	'
Other noncurrent assets, net	1,899	1,650	'	'
Total assets	242,309	231,522	'	'
Accounts payable and accrued expenses related to trade creditors	5,520	6,198	'	'
Accrued participations and residuals	1,239	1,350	'	'
Accrued expenses and other current liabilities [condensed]	6,678	4,690	'	'
Current portion of long-term debt	26	23	'	'
Total current liabilities	13,463	12,261	'	'
Long-term debt, less current portion	5,697	105	'	'
Deferred income taxes	31,840	30,035	'	'
Other noncurrent liabilities	8,675	10,604	'	'
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	957	16,998	'	'
Other shareholders' equity	181,313	161,079	'	'
Total Parent Company equity	181,313	161,079	'	'
Noncontrolling interests	364	440	'	'
Total equity	181,677	161,519	'	'
Total liabilities and equity	242,309	231,522	'	'
Elimination and Consolidation Adjustments [Member]	'	'	'	'
Investments in and amounts due from subsidiaries eliminated upon consolidation	-460,590	-420,714	'	'
Other noncurrent assets, net	-882	-900	'	'
Total assets	-461,472	-421,614	'	'
Deferred income taxes	-741	-757	'	'
Other noncurrent liabilities	-141	-143	'	'
Other shareholders' equity	-460,590	-420,714	'	'
Total Parent Company equity	-460,590	-420,714	'	'
Total equity	-460,590	-420,714	'	'
Total liabilities and equity	($461,472)	($421,614)	'	'

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information (Condensed Consolidating Statement of Income) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Service revenue	'	'	'	'	'	'	'	'	$64,657	$62,570	$55,842
Revenue	16,926	16,151	16,270	15,310	15,937	16,544	15,211	14,878	64,657	62,570	55,842
Programming and production	'	'	'	'	'	'	'	'	19,670	19,929	16,596
Other operating and administrative	'	'	'	'	'	'	'	'	18,584	17,833	16,646
Advertising, marketing and promotion	'	'	'	'	'	'	'	'	4,969	4,831	4,243
Depreciation	'	'	'	'	'	'	'	'	6,254	6,150	6,040
Amortization	'	'	'	'	'	'	'	'	1,617	1,648	1,596
Costs and expenses, total	'	'	'	'	'	'	'	'	51,094	50,391	45,121
Operating income (loss)	3,647	3,414	3,435	3,067	3,294	3,048	3,079	2,758	13,563	12,179	10,721
Interest expense	'	'	'	'	'	'	'	'	-2,574	-2,521	-2,505
Investment income (loss), net	'	'	'	'	'	'	'	'	576	219	159
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	-86	959	-35
Other income (expense), net	'	'	'	'	'	'	'	'	-364	773	-133
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	-2,448	-570	-2,514
Income (loss) before income taxes	'	'	'	'	'	'	'	'	11,115	11,609	8,207
Income tax (expense) benefit	'	'	'	'	'	'	'	'	-3,980	-3,744	-3,050
Net income (loss)	'	'	'	'	'	'	'	'	7,135	7,865	5,157
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	'	'	'	'	'	'	'	'	-319	-1,662	-997
Net income (loss) attributable to Parent	1,913	1,732	1,734	1,437	1,518	2,113	1,348	1,224	6,816	6,203	4,160
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	6,883	6,370	4,107
Comcast [Member]	'	'	'	'	'	'	'	'	'	'	'
Management fee revenue	'	'	'	'	'	'	'	'	897	848	800
Revenue	'	'	'	'	'	'	'	'	897	848	800
Other operating and administrative	'	'	'	'	'	'	'	'	403	401	420
Depreciation	'	'	'	'	'	'	'	'	30	30	29
Amortization	'	'	'	'	'	'	'	'	5	4	3
Costs and expenses, total	'	'	'	'	'	'	'	'	438	435	452
Operating income (loss)	'	'	'	'	'	'	'	'	459	413	348
Interest expense	'	'	'	'	'	'	'	'	-1,523	-1,430	-1,439
Investment income (loss), net	'	'	'	'	'	'	'	'	'	8	3
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	7,509	6,858	4,879
Other income (expense), net	'	'	'	'	'	'	'	'	-2	2	-19
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	5,984	5,438	3,424
Income (loss) before income taxes	'	'	'	'	'	'	'	'	6,443	5,851	3,772
Income tax (expense) benefit	'	'	'	'	'	'	'	'	373	352	388
Net income (loss)	'	'	'	'	'	'	'	'	6,816	6,203	4,160
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	6,816	6,203	4,160
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	6,883	6,370	4,107
Comcast Holdings [Member]	'	'	'	'	'	'	'	'	'	'	'
Other operating and administrative	'	'	'	'	'	'	'	'	'	'	5
Costs and expenses, total	'	'	'	'	'	'	'	'	'	'	5
Operating income (loss)	'	'	'	'	'	'	'	'	'	'	-5
Interest expense	'	'	'	'	'	'	'	'	-11	-23	-32
Investment income (loss), net	'	'	'	'	'	'	'	'	-13	3	2
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	7,540	6,536	5,734
Other income (expense), net	'	'	'	'	'	'	'	'	'	'	1
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	7,516	6,516	5,705
Income (loss) before income taxes	'	'	'	'	'	'	'	'	7,516	6,516	5,700
Income tax (expense) benefit	'	'	'	'	'	'	'	'	9	7	12
Net income (loss)	'	'	'	'	'	'	'	'	7,525	6,523	5,712
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	7,525	6,523	5,712
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	7,521	6,523	5,712
CCCL Parent [Member]	'	'	'	'	'	'	'	'	'	'	'
Management fee revenue	'	'	'	'	'	'	'	'	874	827	784
Revenue	'	'	'	'	'	'	'	'	874	827	784
Other operating and administrative	'	'	'	'	'	'	'	'	874	827	784
Costs and expenses, total	'	'	'	'	'	'	'	'	874	827	784
Interest expense	'	'	'	'	'	'	'	'	-212	-329	-338
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	7,430	6,665	5,598
Other income (expense), net	'	'	'	'	'	'	'	'	2	'	'
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	7,220	6,336	5,260
Income (loss) before income taxes	'	'	'	'	'	'	'	'	7,220	6,336	5,260
Income tax (expense) benefit	'	'	'	'	'	'	'	'	73	115	118
Net income (loss)	'	'	'	'	'	'	'	'	7,293	6,451	5,378
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	7,293	6,451	5,378
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	7,276	6,460	5,387
Combined CCHMO Parents [Member]	'	'	'	'	'	'	'	'	'	'	'
Management fee revenue	'	'	'	'	'	'	'	'	548	516	488
Revenue	'	'	'	'	'	'	'	'	548	516	488
Other operating and administrative	'	'	'	'	'	'	'	'	548	516	488
Costs and expenses, total	'	'	'	'	'	'	'	'	548	516	488
Interest expense	'	'	'	'	'	'	'	'	-126	-135	-172
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	5,473	4,909	3,361
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	5,347	4,774	3,189
Income (loss) before income taxes	'	'	'	'	'	'	'	'	5,347	4,774	3,189
Income tax (expense) benefit	'	'	'	'	'	'	'	'	44	47	60
Net income (loss)	'	'	'	'	'	'	'	'	5,391	4,821	3,249
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	5,391	4,821	3,249
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	5,392	4,821	3,249
NBCUniversal Media Parent [Member]	'	'	'	'	'	'	'	'	'	'	'
Other operating and administrative	'	'	'	'	'	'	'	'	855	899	678
Costs and expenses, total	'	'	'	'	'	'	'	'	855	899	678
Operating income (loss)	'	'	'	'	'	'	'	'	-855	-899	-678
Interest expense	'	'	'	'	'	'	'	'	-488	-430	-370
Investment income (loss), net	'	'	'	'	'	'	'	'	3	5	'
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	3,331	4,402	2,793
Other income (expense), net	'	'	'	'	'	'	'	'	-1	-14	-59
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	2,845	3,963	2,364
Income (loss) before income taxes	'	'	'	'	'	'	'	'	1,990	3,064	1,686
Income tax (expense) benefit	'	'	'	'	'	'	'	'	-22	-9	-3
Net income (loss)	'	'	'	'	'	'	'	'	1,968	3,055	1,683
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	1,968	3,055	1,683
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	2,017	3,068	1,605
Comcast Non-Guarantor Subsidiaries [Member]	'	'	'	'	'	'	'	'	'	'	'
Service revenue	'	'	'	'	'	'	'	'	64,657	62,570	55,842
Revenue	'	'	'	'	'	'	'	'	64,657	62,570	55,842
Programming and production	'	'	'	'	'	'	'	'	19,670	19,929	16,596
Other operating and administrative	'	'	'	'	'	'	'	'	18,223	17,381	16,343
Advertising, marketing and promotion	'	'	'	'	'	'	'	'	4,969	4,831	4,243
Depreciation	'	'	'	'	'	'	'	'	6,224	6,120	6,011
Amortization	'	'	'	'	'	'	'	'	1,612	1,644	1,593
Costs and expenses, total	'	'	'	'	'	'	'	'	50,698	49,905	44,786
Operating income (loss)	'	'	'	'	'	'	'	'	13,959	12,665	11,056
Interest expense	'	'	'	'	'	'	'	'	-214	-174	-154
Investment income (loss), net	'	'	'	'	'	'	'	'	586	203	154
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	1,882	4,014	1,648
Other income (expense), net	'	'	'	'	'	'	'	'	-363	785	-56
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	1,891	4,828	1,592
Income (loss) before income taxes	'	'	'	'	'	'	'	'	15,850	17,493	12,648
Income tax (expense) benefit	'	'	'	'	'	'	'	'	-4,457	-4,256	-3,625
Net income (loss)	'	'	'	'	'	'	'	'	11,393	13,237	9,023
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	'	'	'	'	'	'	'	'	-319	-1,662	-997
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	11,074	11,575	8,026
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	10,969	11,703	8,064
Elimination and Consolidation Adjustments [Member]	'	'	'	'	'	'	'	'	'	'	'
Management fee revenue	'	'	'	'	'	'	'	'	-2,319	-2,191	-2,072
Revenue	'	'	'	'	'	'	'	'	-2,319	-2,191	-2,072
Other operating and administrative	'	'	'	'	'	'	'	'	-2,319	-2,191	-2,072
Costs and expenses, total	'	'	'	'	'	'	'	'	-2,319	-2,191	-2,072
Equity in net income (losses) of investees, net	'	'	'	'	'	'	'	'	-33,251	-32,425	-24,048
Nonoperating income (Expense), Total	'	'	'	'	'	'	'	'	-33,251	-32,425	-24,048
Income (loss) before income taxes	'	'	'	'	'	'	'	'	-33,251	-32,425	-24,048
Net income (loss)	'	'	'	'	'	'	'	'	-33,251	-32,425	-24,048
Net income (loss) attributable to Parent	'	'	'	'	'	'	'	'	-33,251	-32,425	-24,048
Comprehensive income attributable to Parent	'	'	'	'	'	'	'	'	($33,175)	($32,575)	($24,017)

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information (Condensed Consolidating Statement of Cash Flows) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	$14,160	$14,854	$14,345
Investing Activities	'	'	'
Capital expenditures	-6,596	-5,714	-5,307
Cash paid for intangible assets	-1,009	-923	-954
Acquisitions of real estate properties	-1,904	'	'
Acquisitions, net of cash acquired	-99	-90	-6,407
Proceeds from sales of businesses and investments	1,083	3,102	277
Return of capital from investees	149	2,362	37
Purchases of investments	-1,223	-297	-135
Other	85	74	-19
Net cash provided by (used in) investing activities	-9,514	-1,486	-12,508
Financing Activities	'	'	'
Proceeds from (repayments of) short-term borrowings, net	1,345	-544	544
Proceeds from borrowings	2,933	4,544	'
Repurchases and repayments of debt	-2,444	-2,881	-3,216
Repurchases and retirements of common stock	-2,000	-3,000	-2,141
Dividends paid	-1,964	-1,608	-1,187
Issuances of common stock	40	233	283
Purchase of NBCUniversal noncontrolling common equity interest	-10,761	'	'
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock	-215	-691	-325
Settlement of Station Venture liability	-602	'	'
Other	-211	-90	-159
Net cash provided by (used in) financing activities	-13,879	-4,037	-6,201
Increase (decrease) in cash and cash equivalents	-9,233	9,331	-4,364
Cash and cash equivalents, beginning of year	10,951	1,620	5,984
Cash and cash equivalents, end of year	1,718	10,951	1,620
Comcast [Member]	'	'	'
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	-600	-362	-513
Investing Activities	'	'	'
Net transactions with affiliates	66	3,845	4,615
Capital expenditures	-7	-10	-7
Cash paid for intangible assets	-4	-6	-2
Purchases of investments	-11	'	'
Net cash provided by (used in) investing activities	44	3,829	4,606
Financing Activities	'	'	'
Proceeds from (repayments of) short-term borrowings, net	1,349	-1	-4
Proceeds from borrowings	2,933	2,536	'
Repurchases and repayments of debt	'	-1,726	-1,095
Repurchases and retirements of common stock	-2,000	-3,000	-2,141
Dividends paid	-1,964	-1,608	-1,187
Issuances of common stock	40	233	283
Other	198	99	51
Net cash provided by (used in) financing activities	556	-3,467	-4,093
Comcast Holdings [Member]	'	'	'
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	-3	-7	-19
Investing Activities	'	'	'
Net transactions with affiliates	3	206	19
Other	'	3	'
Net cash provided by (used in) investing activities	3	209	19
Financing Activities	'	'	'
Repurchases and repayments of debt	'	-202	'
Net cash provided by (used in) financing activities	'	-202	'
CCCL Parent [Member]	'	'	'
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	-151	-177	-209
Investing Activities	'	'	'
Net transactions with affiliates	2,248	177	1,209
Net cash provided by (used in) investing activities	2,248	177	1,209
Financing Activities	'	'	'
Repurchases and repayments of debt	-2,097	'	-1,000
Net cash provided by (used in) financing activities	-2,097	'	-1,000
Combined CCHMO Parents [Member]	'	'	'
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	-94	-114	-131
Investing Activities	'	'	'
Net transactions with affiliates	332	667	131
Net cash provided by (used in) investing activities	332	667	131
Financing Activities	'	'	'
Repurchases and repayments of debt	-238	-553	'
Net cash provided by (used in) financing activities	-238	-553	'
NBCUniversal Media Parent [Member]	'	'	'
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	-1,102	-1,347	-638
Investing Activities	'	'	'
Net transactions with affiliates	-470	4,850	247
Acquisitions, net of cash acquired	'	'	295
Proceeds from sales of businesses and investments	2	'	3
Return of capital from investees	128	'	'
Purchases of investments	-3	-19	-4
Other	-20	-22	'
Net cash provided by (used in) investing activities	-363	4,809	541
Financing Activities	'	'	'
Proceeds from (repayments of) short-term borrowings, net	'	-550	550
Proceeds from borrowings	'	1,995	'
Repurchases and repayments of debt	-88	-2	'
Purchase of NBCUniversal noncontrolling common equity interest	-3,200	'	'
Other	-40	-14	-215
Net cash provided by (used in) financing activities	-3,328	1,429	335
Increase (decrease) in cash and cash equivalents	-4,793	4,891	238
Cash and cash equivalents, beginning of year	5,129	238	'
Cash and cash equivalents, end of year	336	5,129	238
Comcast Non-Guarantor Subsidiaries [Member]	'	'	'
Operating Activities	'	'	'
Net cash provided by (used in) operating activities	16,110	16,861	15,855
Investing Activities	'	'	'
Net transactions with affiliates	-2,179	-9,745	-6,221
Capital expenditures	-6,589	-5,704	-5,300
Cash paid for intangible assets	-1,005	-917	-952
Acquisitions of real estate properties	-1,904	'	'
Acquisitions, net of cash acquired	-99	-90	-6,702
Proceeds from sales of businesses and investments	1,081	3,102	274
Return of capital from investees	21	2,362	37
Purchases of investments	-1,209	-278	-131
Other	105	93	-19
Net cash provided by (used in) investing activities	-11,778	-11,177	-19,014
Financing Activities	'	'	'
Proceeds from (repayments of) short-term borrowings, net	-4	7	-2
Proceeds from borrowings	0	13	'
Repurchases and repayments of debt	-21	-398	-1,121
Purchase of NBCUniversal noncontrolling common equity interest	-7,561	'	'
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock	-215	-691	-325
Settlement of Station Venture liability	-602	'	'
Other	-369	-175	5
Net cash provided by (used in) financing activities	-8,772	-1,244	-1,443
Increase (decrease) in cash and cash equivalents	-4,440	4,440	-4,602
Cash and cash equivalents, beginning of year	5,822	1,382	5,984
Cash and cash equivalents, end of year	$1,382	$5,822	$1,382

Schedule_II_Valuation_and_Qual2

Schedule II Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended			11 Months Ended	12 Months Ended					11 Months Ended	12 Months Ended					11 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
	Allowance for Doubtful Accounts [Member]	Allowance for Doubtful Accounts [Member]	Allowance for Doubtful Accounts [Member]	Allowance for Doubtful Accounts [Member]	Allowance for Doubtful Accounts [Member]	Allowance for Doubtful Accounts [Member]	Sales Returns and Allowances [Member]	Sales Returns and Allowances [Member]	Sales Returns and Allowances [Member]	Sales Returns and Allowances [Member]	Sales Returns and Allowances [Member]	Sales Returns and Allowances [Member]	Deferred Tax Valuation Allowance	Deferred Tax Valuation Allowance	Deferred Tax Valuation Allowance	Deferred Tax Valuation Allowance	Deferred Tax Valuation Allowance	Deferred Tax Valuation Allowance
				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]				NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]	NBCUniversal Media, LLC [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'	'
Balance at Beginning of Year	$198	$202	$173	$7	$46	$34	$307	$425	$0	$0	$307	$425	$355	$297	$207	$57	$73	$53
Additions Charged to Costs and Expenses	317	293	306	35	33	19	528	599	536	536	525	599	71	61	103	9	8	23
Deductions from Reserves	294	297	277	8	14	7	460	717	111	111	460	717	21	3	13	13	21	3
Balance at End of Year	$221	$198	$202	$34	$65	$46	$375	$307	$425	$425	$372	$307	$405	$355	$297	$53	$60	$73