Condensed Consolidating Financial Information (Condensed Consolidating Statement of Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Service revenue	$ 19,269	$ 18,743	$ 38,059	$ 36,596
Management fee revenue	0	0	0	0
Revenue	19,269	18,743	38,059	36,596
Costs and Expenses:
Programming and production	5,492	5,669	10,923	11,132
Other operating and administrative	5,761	5,274	11,286	10,348
Advertising, marketing and promotion	1,561	1,534	3,028	2,894
Depreciation	1,868	1,674	3,653	3,308
Amortization	521	487	1,014	919
Costs and expenses, total	15,203	14,638	29,904	28,601
Operating income (loss)	4,066	4,105	8,155	7,995
Other Income (Expense):
Interest expense	(732)	(713)	(1,435)	(1,369)
Investment income (loss), net	58	17	88	50
Equity in net income (losses) of investees, net	(19)	(236)	(30)	(203)
Other income (expense), net	(15)	315	115	417
Nonoperating income (Expense), Total	(708)	(617)	(1,262)	(1,105)
Income (loss) before income taxes	3,358	3,488	6,893	6,890
Income tax (expense) benefit	(1,278)	(1,313)	(2,589)	(2,574)
Net income (loss)	2,080	2,175	4,304	4,316
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	(52)	(38)	(142)	(120)
Net income (loss) attributable to Parent	2,028	2,137	4,162	4,196
Comprehensive income attributable to Parent	2,113	2,159	4,337	4,176
Elimination and Consolidation Adjustments [Member]
Service revenue	0	0	0	0
Management fee revenue	(527)	(498)	(1,040)	(979)
Revenue	(527)	(498)	(1,040)	(979)
Costs and Expenses:
Programming and production	0	0	0	0
Other operating and administrative	(527)	(498)	(1,040)	(979)
Advertising, marketing and promotion	0	0	0	0
Depreciation	0	0	0	0
Amortization	0	0	0	0
Costs and expenses, total	(527)	(498)	(1,040)	(979)
Operating income (loss)	0	0	0	0
Other Income (Expense):
Interest expense	0	0	0	0
Investment income (loss), net	0	0	0	0
Equity in net income (losses) of investees, net	(8,977)	(8,806)	(18,020)	(17,429)
Other income (expense), net	0	0	0	0
Nonoperating income (Expense), Total	(8,977)	(8,806)	(18,020)	(17,429)
Income (loss) before income taxes	(8,977)	(8,806)	(18,020)	(17,429)
Income tax (expense) benefit	0	0	0	0
Net income (loss)	(8,977)	(8,806)	(18,020)	(17,429)
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0	0	0	0
Net income (loss) attributable to Parent	(8,977)	(8,806)	(18,020)	(17,429)
Comprehensive income attributable to Parent	(9,698)	(8,838)	(18,933)	(17,391)
Comcast Parent [Member]
Service revenue	0	0	0	0
Management fee revenue	266	252	525	496
Revenue	266	252	525	496
Costs and Expenses:
Programming and production	0	0	0	0
Other operating and administrative	285	225	441	451
Advertising, marketing and promotion	0	0	0	0
Depreciation	6	7	14	15
Amortization	2	2	3	3
Costs and expenses, total	293	234	458	469
Operating income (loss)	(27)	18	67	27
Other Income (Expense):
Interest expense	(478)	(472)	(929)	(882)
Investment income (loss), net	3	0	3	1
Equity in net income (losses) of investees, net	2,354	2,431	4,720	4,753
Other income (expense), net	0	2	0	(3)
Nonoperating income (Expense), Total	1,879	1,961	3,794	3,869
Income (loss) before income taxes	1,852	1,979	3,861	3,896
Income tax (expense) benefit	176	158	301	300
Net income (loss)	2,028	2,137	4,162	4,196
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0	0	0	0
Net income (loss) attributable to Parent	2,028	2,137	4,162	4,196
Comprehensive income attributable to Parent	2,113	2,159	4,337	4,176
Comcast Holdings [Member]
Service revenue	0	0	0	0
Management fee revenue	0	0	0	0
Revenue	0	0	0	0
Costs and Expenses:
Programming and production	0	0	0	0
Other operating and administrative	0	0	0	0
Advertising, marketing and promotion	0	0	0	0
Depreciation	0	0	0	0
Amortization	0	0	0	0
Costs and expenses, total	0	0	0	0
Operating income (loss)	0	0	0	0
Other Income (Expense):
Interest expense	(3)	(3)	(6)	(6)
Investment income (loss), net	1	(1)	1	1
Equity in net income (losses) of investees, net	2,275	2,162	4,539	4,388
Other income (expense), net	0	0	0	0
Nonoperating income (Expense), Total	2,273	2,158	4,534	4,383
Income (loss) before income taxes	2,273	2,158	4,534	4,383
Income tax (expense) benefit	1	2	2	2
Net income (loss)	2,274	2,160	4,536	4,385
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0	0	0	0
Net income (loss) attributable to Parent	2,274	2,160	4,536	4,385
Comprehensive income attributable to Parent	2,321	2,168	4,627	4,377
CCCL Parent [Member]
Service revenue	0	0	0	0
Management fee revenue	261	246	515	483
Revenue	261	246	515	483
Costs and Expenses:
Programming and production	0	0	0	0
Other operating and administrative	261	246	515	483
Advertising, marketing and promotion	0	0	0	0
Depreciation	0	0	0	0
Amortization	0	0	0	0
Costs and expenses, total	261	246	515	483
Operating income (loss)	0	0	0	0
Other Income (Expense):
Interest expense	(61)	(73)	(120)	(146)
Investment income (loss), net	0	0	0	0
Equity in net income (losses) of investees, net	2,127	2,020	4,241	4,012
Other income (expense), net	0	0	0	0
Nonoperating income (Expense), Total	2,066	1,947	4,121	3,866
Income (loss) before income taxes	2,066	1,947	4,121	3,866
Income tax (expense) benefit	21	26	42	51
Net income (loss)	2,087	1,973	4,163	3,917
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0	0	0	0
Net income (loss) attributable to Parent	2,087	1,973	4,163	3,917
Comprehensive income attributable to Parent	2,087	1,973	4,165	3,915
NBCUniversal Media Parent [Member]
Service revenue	0	0	0	0
Management fee revenue	0	0	0	0
Revenue	0	0	0	0
Costs and Expenses:
Programming and production	0	0	0	0
Other operating and administrative	222	255	517	492
Advertising, marketing and promotion	0	0	0	0
Depreciation	0	0	0	0
Amortization	0	0	0	0
Costs and expenses, total	222	255	517	492
Operating income (loss)	(222)	(255)	(517)	(492)
Other Income (Expense):
Interest expense	(112)	(116)	(229)	(236)
Investment income (loss), net	(6)	(8)	(8)	(14)
Equity in net income (losses) of investees, net	1,288	1,281	2,585	2,512
Other income (expense), net	(7)	16	117	5
Nonoperating income (Expense), Total	1,163	1,173	2,465	2,267
Income (loss) before income taxes	941	918	1,948	1,775
Income tax (expense) benefit	(8)	(6)	(13)	(11)
Net income (loss)	933	912	1,935	1,764
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	0	0	0	0
Net income (loss) attributable to Parent	933	912	1,935	1,764
Comprehensive income attributable to Parent	1,096	936	2,242	1,737
Comcast Non-Guarantor Subsidiaries [Member]
Service revenue	19,269	18,743	38,059	36,596
Management fee revenue	0	0	0	0
Revenue	19,269	18,743	38,059	36,596
Costs and Expenses:
Programming and production	5,492	5,669	10,923	11,132
Other operating and administrative	5,520	5,046	10,853	9,901
Advertising, marketing and promotion	1,561	1,534	3,028	2,894
Depreciation	1,862	1,667	3,639	3,293
Amortization	519	485	1,011	916
Costs and expenses, total	14,954	14,401	29,454	28,136
Operating income (loss)	4,315	4,342	8,605	8,460
Other Income (Expense):
Interest expense	(78)	(49)	(151)	(99)
Investment income (loss), net	60	26	92	62
Equity in net income (losses) of investees, net	914	676	1,905	1,561
Other income (expense), net	(8)	297	(2)	415
Nonoperating income (Expense), Total	888	950	1,844	1,939
Income (loss) before income taxes	5,203	5,292	10,449	10,399
Income tax (expense) benefit	(1,468)	(1,493)	(2,921)	(2,916)
Net income (loss)	3,735	3,799	7,528	7,483
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock	(52)	(38)	(142)	(120)
Net income (loss) attributable to Parent	3,683	3,761	7,386	7,363
Comprehensive income attributable to Parent	$ 4,194	$ 3,761	$ 7,899	$ 7,362