Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheet) (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Assets
Cash and cash equivalents	$ 4,665	$ 2,295	$ 3,486	$ 3,910
Receivables, net	6,708	6,896
Programming rights	1,435	1,213
Other current assets	1,969	1,899
Total current assets	14,777	12,303
Film and television costs	5,811	5,855
Investments	3,679	3,224
Investments in and amounts due from subsidiaries eliminated upon consolidation	0	0
Property and equipment, net	34,896	33,665
Franchise rights	59,364	59,364
Goodwill	33,792	32,945
Other intangible assets, net	17,204	16,946
Other noncurrent assets, net	2,462	2,272
Total assets	171,985	166,574
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	6,359	6,215
Accrued participations and residuals	1,542	1,572
Accrued expenses and other current liabilities [condensed]	6,766	6,764
Current portion of long-term debt	2,934	3,627
Total current liabilities	17,601	18,178
Long-term debt, less current portion	52,629	48,994
Deferred income taxes	34,512	33,566
Other noncurrent liabilities	10,719	10,637
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	1,248	1,221
Equity:
Common stock	28	29
Other shareholders' equity	53,070	52,240
Total Comcast Corporation shareholders' equity	53,098	52,269
Noncontrolling interests	2,178	1,709
Total equity	55,276	53,978	52,729	53,068
Total liabilities and equity	171,985	166,574
Comcast Parent [Member]
Assets
Cash and cash equivalents	0	0	0	0
Receivables, net	0	0
Programming rights	0	0
Other current assets	138	69
Total current assets	138	69
Film and television costs	0	0
Investments	48	33
Investments in and amounts due from subsidiaries eliminated upon consolidation	91,382	87,142
Property and equipment, net	218	210
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	10	12
Other noncurrent assets, net	1,361	1,301
Total assets	93,157	88,767
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	31	16
Accrued participations and residuals	0	0
Accrued expenses and other current liabilities [condensed]	1,672	1,789
Current portion of long-term debt	1,000	1,149
Total current liabilities	2,703	2,954
Long-term debt, less current portion	34,757	31,106
Deferred income taxes	0	0
Other noncurrent liabilities	2,599	2,438
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	28	29
Other shareholders' equity	53,070	52,240
Total Comcast Corporation shareholders' equity	53,098	52,269
Noncontrolling interests	0	0
Total equity	53,098	52,269
Total liabilities and equity	93,157	88,767
Comcast Holdings [Member]
Assets
Cash and cash equivalents	0	0	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	115,253	111,241
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	147	147
Total assets	115,400	111,388
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	335
Current portion of long-term debt	0	0
Total current liabilities	335	335
Long-term debt, less current portion	133	130
Deferred income taxes	581	624
Other noncurrent liabilities	0	0
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	114,351	110,299
Total Comcast Corporation shareholders' equity	114,351	110,299
Noncontrolling interests	0	0
Total equity	114,351	110,299
Total liabilities and equity	115,400	111,388
CCCL Parent [Member]
Assets
Cash and cash equivalents	0	0	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	123,620	119,354
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	123,620	119,354
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]	282	290
Current portion of long-term debt	550	0
Total current liabilities	832	290
Long-term debt, less current portion	2,100	2,650
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	120,688	116,414
Total Comcast Corporation shareholders' equity	120,688	116,414
Noncontrolling interests	0	0
Total equity	120,688	116,414
Total liabilities and equity	123,620	119,354
NBCUniversal Media Parent [Member]
Assets
Cash and cash equivalents	270	414	299	385
Receivables, net	0	0
Programming rights	0	0
Other current assets	49	17
Total current assets	319	431
Film and television costs	0	0
Investments	445	430
Investments in and amounts due from subsidiaries eliminated upon consolidation	42,893	42,441
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	85	78
Total assets	43,742	43,380
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]	282	389
Current portion of long-term debt	4	1,005
Total current liabilities	286	1,394
Long-term debt, less current portion	8,228	8,211
Deferred income taxes	69	66
Other noncurrent liabilities	1,143	1,087
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	34,016	32,622
Total Comcast Corporation shareholders' equity	34,016	32,622
Noncontrolling interests	0	0
Total equity	34,016	32,622
Total liabilities and equity	43,742	43,380
Comcast Non-Guarantor Subsidiaries [Member]
Assets
Cash and cash equivalents	4,395	1,881	3,187	3,525
Receivables, net	6,708	6,896
Programming rights	1,435	1,213
Other current assets	1,782	1,813
Total current assets	14,320	11,803
Film and television costs	5,811	5,855
Investments	3,186	2,761
Investments in and amounts due from subsidiaries eliminated upon consolidation	113,686	109,598
Property and equipment, net	34,678	33,455
Franchise rights	59,364	59,364
Goodwill	33,792	32,945
Other intangible assets, net	17,194	16,934
Other noncurrent assets, net	2,117	2,114
Total assets	284,148	274,829
Liabilities and Equity
Accounts payable and accrued expenses related to trade creditors	6,328	6,199
Accrued participations and residuals	1,542	1,572
Accrued expenses and other current liabilities [condensed]	4,195	3,961
Current portion of long-term debt	1,380	1,473
Total current liabilities	13,445	13,205
Long-term debt, less current portion	7,411	6,897
Deferred income taxes	34,964	34,098
Other noncurrent liabilities	7,123	7,258
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	1,248	1,221
Equity:
Common stock	0	0
Other shareholders' equity	217,779	210,441
Total Comcast Corporation shareholders' equity	217,779	210,441
Noncontrolling interests	2,178	1,709
Total equity	219,957	212,150
Total liabilities and equity	284,148	274,829
Elimination and Consolidation Adjustments [Member]
Assets
Cash and cash equivalents	0	0	$ 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	(486,834)	(469,776)
Property and equipment, net	0	0
Franchise rights	0	0
Goodwill	0	0
Other intangible assets, net	0	0
Other noncurrent assets, net	(1,248)	(1,368)
Total assets	(488,082)	(471,144)
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	(1,102)	(1,222)
Other noncurrent liabilities	(146)	(146)
Redeemable noncontrolling interests and redeemable subsidiary preferred stock	0	0
Equity:
Common stock	0	0
Other shareholders' equity	(486,834)	(469,776)
Total Comcast Corporation shareholders' equity	(486,834)	(469,776)
Noncontrolling interests	0	0
Total equity	(486,834)	(469,776)
Total liabilities and equity	$ (488,082)	$ (471,144)