Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Cash and cash equivalents	$ 2,295	$ 3,910	$ 1,718	$ 10,951
Investments [Current]	106	602
Receivables, net	6,896	6,321
Programming rights	1,213	839
Other current assets	1,793	1,859
Total current assets	12,303	13,531
Film and television costs	5,855	5,727
Investments	3,224	3,135
Property and equipment, net	33,665	30,953
Franchise rights	59,364	59,364
Goodwill	32,945	27,316	27,098
Other intangible assets, net	16,946	16,980
Other noncurrent assets, net	2,272	2,180
Total assets	166,574	159,186
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	6,215	5,638
Accrued participations and residuals	1,572	1,347
Accrued expenses and other current liabilities [condensed]	6,764	6,208
Current portion of long-term debt	3,627	4,217
Total current liabilities	18,178	17,410
Long-term debt, less current portion	48,994	43,864
Deferred income taxes	33,566	32,959
Other noncurrent liabilities	10,637	10,819
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	1,221	1,066
Equity:
Common stock	29	30
Other shareholders' equity	52,240	52,681
Total Comcast Corporation shareholders' equity	52,269	52,711
Noncontrolling interests	1,709	357
Total equity	53,978	53,068	51,058	49,796
Total liabilities and equity	166,574	159,186
Comcast Parent [Member]
Assets
Cash and cash equivalents	0	0	0	0
Investments [Current]	0	0
Receivables, net	0	0
Programming rights	0	0
Other current assets	69	267
Total current assets	69	267
Film and television costs	0	0
Investments	33	36
Investments in and amounts due from subsidiaries eliminated upon consolidation	87,142	84,142
Property and equipment, net	210	199
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	12	11
Other noncurrent assets, net	1,301	1,086
Total assets	88,767	85,741
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	16	19
Accrued participations and residuals	0	0
Accrued expenses and other current liabilities [condensed]	1,789	1,547
Current portion of long-term debt	1,149	1,650
Total current liabilities	2,954	3,216
Long-term debt, less current portion	31,106	27,478
Deferred income taxes	0	0
Other noncurrent liabilities	2,438	2,336
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	29	30
Other shareholders' equity	52,240	52,681
Total Comcast Corporation shareholders' equity	52,269	52,711
Noncontrolling interests	0	0
Total equity	52,269	52,711
Total liabilities and equity	88,767	85,741
Comcast Holdings [Member]
Assets
Cash and cash equivalents	0	0	0	0
Investments [Current]	0	0
Receivables, net	0	0
Programming rights	0	0
Other current assets	0	0
Total current assets	0	0
Film and television costs	0	0
Investments	0	0
Investments in and amounts due from subsidiaries eliminated upon consolidation	111,241	103,420
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	147	145
Total assets	111,388	103,565
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	0	0
Accrued participations and residuals	0	0
Accrued expenses and other current liabilities [condensed]	335	283
Current portion of long-term debt	0	0
Total current liabilities	335	283
Long-term debt, less current portion	130	123
Deferred income taxes	624	701
Other noncurrent liabilities	0	0
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	110,299	102,458
Total Comcast Corporation shareholders' equity	110,299	102,458
Noncontrolling interests	0	0
Total equity	110,299	102,458
Total liabilities and equity	111,388	103,565
CCCL Parent [Member]
Assets
Cash and cash equivalents	0	0	0	0
Investments [Current]	0	0
Receivables, net	0	0
Programming rights	0	0
Other current assets	0	0
Total current assets	0	0
Film and television costs	0	0
Investments	0	0
Investments in and amounts due from subsidiaries eliminated upon consolidation	119,354	111,870
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	0	0
Total assets	119,354	111,870
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	0	1
Accrued participations and residuals	0	0
Accrued expenses and other current liabilities [condensed]	290	280
Current portion of long-term debt	0	677
Total current liabilities	290	958
Long-term debt, less current portion	2,650	2,649
Deferred income taxes	0	0
Other noncurrent liabilities	0	0
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	116,414	108,263
Total Comcast Corporation shareholders' equity	116,414	108,263
Noncontrolling interests	0	0
Total equity	116,414	108,263
Total liabilities and equity	119,354	111,870
NBCUniversal Media Parent [Member]
Assets
Cash and cash equivalents	414	385	336	5,129
Investments [Current]	0	0
Receivables, net	0	0
Programming rights	0	0
Other current assets	17	41
Total current assets	431	426
Film and television costs	0	0
Investments	430	378
Investments in and amounts due from subsidiaries eliminated upon consolidation	42,441	41,239
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	78	80
Total assets	43,380	42,123
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	0	0
Accrued participations and residuals	0	0
Accrued expenses and other current liabilities [condensed]	389	331
Current portion of long-term debt	1,005	1,006
Total current liabilities	1,394	1,337
Long-term debt, less current portion	8,211	9,206
Deferred income taxes	66	67
Other noncurrent liabilities	1,087	1,143
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	32,622	30,370
Total Comcast Corporation shareholders' equity	32,622	30,370
Noncontrolling interests	0	0
Total equity	32,622	30,370
Total liabilities and equity	43,380	42,123
Comcast Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	1,881	3,525	1,382	5,822
Investments [Current]	106	602
Receivables, net	6,896	6,321
Programming rights	1,213	839
Other current assets	1,707	1,551
Total current assets	11,803	12,838
Film and television costs	5,855	5,727
Investments	2,761	2,721
Investments in and amounts due from subsidiaries eliminated upon consolidation	109,598	98,152
Property and equipment, net	33,455	30,754
Franchise rights	59,364	59,364
Goodwill	32,945	27,316
Other intangible assets, net	16,934	16,969
Other noncurrent assets, net	2,114	1,949
Total assets	274,829	255,790
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	6,199	5,618
Accrued participations and residuals	1,572	1,347
Accrued expenses and other current liabilities [condensed]	3,961	3,767
Current portion of long-term debt	1,473	884
Total current liabilities	13,205	11,616
Long-term debt, less current portion	6,897	4,408
Deferred income taxes	34,098	33,127
Other noncurrent liabilities	7,258	7,484
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	1,221	1,066
Equity:
Common stock	0	0
Other shareholders' equity	210,441	197,732
Total Comcast Corporation shareholders' equity	210,441	197,732
Noncontrolling interests	1,709	357
Total equity	212,150	198,089
Total liabilities and equity	274,829	255,790
Elimination and Consolidation Adjustments [Member]
Assets
Cash and cash equivalents	0	0	$ 0	$ 0
Investments [Current]	0	0
Receivables, net	0	0
Programming rights	0	0
Other current assets	0	0
Total current assets	0	0
Film and television costs	0	0
Investments	0	0
Investments in and amounts due from subsidiaries eliminated upon consolidation	(469,776)	(438,823)
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	(1,368)	(1,080)
Total assets	(471,144)	(439,903)
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	0	0
Accrued participations and residuals	0	0
Accrued expenses and other current liabilities [condensed]	0	0
Current portion of long-term debt	0	0
Total current liabilities	0	0
Long-term debt, less current portion	0	0
Deferred income taxes	(1,222)	(936)
Other noncurrent liabilities	(146)	(144)
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	(469,776)	(438,823)
Total Comcast Corporation shareholders' equity	(469,776)	(438,823)
Noncontrolling interests	0	0
Total equity	(469,776)	(438,823)
Total liabilities and equity	$ (471,144)	$ (439,903)