Condensed Consolidating Financial Information (Condensed Consolidating Statement of Cash Flows) (Details) - USD ($)
$ in Millions |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
$ 19,240
|
$ 18,778
|
$ 16,945
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
0
|
0
|
0
|
| Capital expenditures |
(9,135)
|
(8,499)
|
(7,420)
|
| Cash paid for intangible assets |
(1,686)
|
(1,370)
|
(1,122)
|
| Acquisitions and construction of real estate properties |
(428)
|
(178)
|
(43)
|
| Acquisitions, net of cash acquired |
(3,929)
|
(1,786)
|
(477)
|
| Proceeds from sales of businesses and investments |
218
|
433
|
666
|
| Purchases of investments |
(1,697)
|
(784)
|
(191)
|
| Deposits |
(1,749)
|
(18)
|
0
|
| Other |
21
|
238
|
(146)
|
| Net cash provided by (used in) investing activities |
(18,385)
|
(11,964)
|
(8,733)
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
1,790
|
135
|
(504)
|
| Proceeds from borrowings |
9,231
|
5,486
|
4,182
|
| Repurchases and repayments of debt |
(3,052)
|
(4,378)
|
(3,175)
|
| Repurchases and retirements of common stock |
(5,000)
|
(6,750)
|
(4,251)
|
| Dividends paid |
(2,601)
|
(2,437)
|
(2,254)
|
| Issuances of common stock |
23
|
36
|
35
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
(253)
|
(232)
|
(220)
|
| Other |
13
|
(289)
|
167
|
| Net cash provided by (used in) financing activities |
151
|
(8,429)
|
(6,020)
|
| Increase (decrease) in cash and cash equivalents |
1,006
|
(1,615)
|
2,192
|
| Cash and cash equivalents, beginning of year |
2,295
|
3,910
|
1,718
|
| Cash and cash equivalents, end of year |
3,301
|
2,295
|
3,910
|
| Comcast Parent [Member] |
|
|
|
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
(1,332)
|
(792)
|
(354)
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
(860)
|
6,559
|
4,784
|
| Capital expenditures |
(13)
|
(27)
|
(3)
|
| Cash paid for intangible assets |
(9)
|
(6)
|
(6)
|
| Acquisitions and construction of real estate properties |
(35)
|
0
|
0
|
| Acquisitions, net of cash acquired |
0
|
0
|
0
|
| Proceeds from sales of businesses and investments |
0
|
0
|
0
|
| Purchases of investments |
(40)
|
(7)
|
(19)
|
| Deposits |
0
|
0
|
0
|
| Other |
(108)
|
7
|
0
|
| Net cash provided by (used in) investing activities |
(1,065)
|
6,526
|
4,756
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
1,339
|
400
|
(1,350)
|
| Proceeds from borrowings |
9,231
|
5,486
|
4,180
|
| Repurchases and repayments of debt |
(750)
|
(2,650)
|
(1,000)
|
| Repurchases and retirements of common stock |
(5,000)
|
(6,750)
|
(4,251)
|
| Dividends paid |
(2,601)
|
(2,437)
|
(2,254)
|
| Issuances of common stock |
23
|
36
|
35
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
0
|
0
|
0
|
| Other |
155
|
181
|
238
|
| Net cash provided by (used in) financing activities |
2,397
|
(5,734)
|
(4,402)
|
| Increase (decrease) in cash and cash equivalents |
0
|
0
|
0
|
| Cash and cash equivalents, beginning of year |
0
|
0
|
0
|
| Cash and cash equivalents, end of year |
0
|
0
|
0
|
| Comcast Holdings [Member] |
|
|
|
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
(189)
|
48
|
9
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
189
|
(48)
|
(9)
|
| Capital expenditures |
0
|
0
|
0
|
| Cash paid for intangible assets |
0
|
0
|
0
|
| Acquisitions and construction of real estate properties |
0
|
0
|
0
|
| Acquisitions, net of cash acquired |
0
|
0
|
0
|
| Proceeds from sales of businesses and investments |
0
|
0
|
0
|
| Purchases of investments |
0
|
0
|
0
|
| Deposits |
0
|
0
|
0
|
| Other |
0
|
0
|
0
|
| Net cash provided by (used in) investing activities |
189
|
(48)
|
(9)
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
0
|
0
|
0
|
| Proceeds from borrowings |
0
|
0
|
0
|
| Repurchases and repayments of debt |
0
|
0
|
0
|
| Repurchases and retirements of common stock |
0
|
0
|
0
|
| Dividends paid |
0
|
0
|
0
|
| Issuances of common stock |
0
|
0
|
0
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
0
|
0
|
0
|
| Other |
0
|
0
|
0
|
| Net cash provided by (used in) financing activities |
0
|
0
|
0
|
| Increase (decrease) in cash and cash equivalents |
0
|
0
|
0
|
| Cash and cash equivalents, beginning of year |
0
|
0
|
0
|
| Cash and cash equivalents, end of year |
0
|
0
|
0
|
| CCCL Parent [Member] |
|
|
|
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
(100)
|
(167)
|
(139)
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
100
|
840
|
139
|
| Capital expenditures |
0
|
0
|
0
|
| Cash paid for intangible assets |
0
|
0
|
0
|
| Acquisitions and construction of real estate properties |
0
|
0
|
0
|
| Acquisitions, net of cash acquired |
0
|
0
|
0
|
| Proceeds from sales of businesses and investments |
0
|
0
|
0
|
| Purchases of investments |
0
|
0
|
0
|
| Deposits |
0
|
0
|
0
|
| Other |
0
|
0
|
0
|
| Net cash provided by (used in) investing activities |
100
|
840
|
139
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
0
|
0
|
0
|
| Proceeds from borrowings |
0
|
0
|
0
|
| Repurchases and repayments of debt |
0
|
(673)
|
0
|
| Repurchases and retirements of common stock |
0
|
0
|
0
|
| Dividends paid |
0
|
0
|
0
|
| Issuances of common stock |
0
|
0
|
0
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
0
|
0
|
0
|
| Other |
0
|
0
|
0
|
| Net cash provided by (used in) financing activities |
0
|
(673)
|
0
|
| Increase (decrease) in cash and cash equivalents |
0
|
0
|
0
|
| Cash and cash equivalents, beginning of year |
0
|
0
|
0
|
| Cash and cash equivalents, end of year |
0
|
0
|
0
|
| NBCUniversal Media Parent [Member] |
|
|
|
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
(1,453)
|
(1,398)
|
(1,299)
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
2,642
|
2,839
|
2,247
|
| Capital expenditures |
0
|
0
|
0
|
| Cash paid for intangible assets |
0
|
0
|
0
|
| Acquisitions and construction of real estate properties |
0
|
0
|
0
|
| Acquisitions, net of cash acquired |
0
|
0
|
0
|
| Proceeds from sales of businesses and investments |
104
|
4
|
8
|
| Purchases of investments |
(210)
|
(407)
|
(10)
|
| Deposits |
0
|
0
|
0
|
| Other |
(35)
|
(5)
|
5
|
| Net cash provided by (used in) investing activities |
2,501
|
2,431
|
2,250
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
0
|
0
|
0
|
| Proceeds from borrowings |
0
|
0
|
0
|
| Repurchases and repayments of debt |
(1,005)
|
(1,004)
|
(902)
|
| Repurchases and retirements of common stock |
0
|
0
|
0
|
| Dividends paid |
0
|
0
|
0
|
| Issuances of common stock |
0
|
0
|
0
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
0
|
0
|
0
|
| Other |
25
|
0
|
0
|
| Net cash provided by (used in) financing activities |
(980)
|
(1,004)
|
(902)
|
| Increase (decrease) in cash and cash equivalents |
68
|
29
|
49
|
| Cash and cash equivalents, beginning of year |
414
|
385
|
336
|
| Cash and cash equivalents, end of year |
482
|
414
|
385
|
| Comcast Non-Guarantor Subsidiaries [Member] |
|
|
|
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
22,314
|
21,087
|
18,728
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
(2,071)
|
(10,190)
|
(7,161)
|
| Capital expenditures |
(9,122)
|
(8,472)
|
(7,417)
|
| Cash paid for intangible assets |
(1,677)
|
(1,364)
|
(1,116)
|
| Acquisitions and construction of real estate properties |
(393)
|
(178)
|
(43)
|
| Acquisitions, net of cash acquired |
(3,929)
|
(1,786)
|
(477)
|
| Proceeds from sales of businesses and investments |
114
|
429
|
658
|
| Purchases of investments |
(1,447)
|
(370)
|
(162)
|
| Deposits |
(1,749)
|
(18)
|
0
|
| Other |
164
|
236
|
(151)
|
| Net cash provided by (used in) investing activities |
(20,110)
|
(21,713)
|
(15,869)
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
451
|
(265)
|
846
|
| Proceeds from borrowings |
0
|
0
|
2
|
| Repurchases and repayments of debt |
(1,297)
|
(51)
|
(1,273)
|
| Repurchases and retirements of common stock |
0
|
0
|
0
|
| Dividends paid |
0
|
0
|
0
|
| Issuances of common stock |
0
|
0
|
0
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
(253)
|
(232)
|
(220)
|
| Other |
(167)
|
(470)
|
(71)
|
| Net cash provided by (used in) financing activities |
(1,266)
|
(1,018)
|
(716)
|
| Increase (decrease) in cash and cash equivalents |
938
|
(1,644)
|
2,143
|
| Cash and cash equivalents, beginning of year |
1,881
|
3,525
|
1,382
|
| Cash and cash equivalents, end of year |
2,819
|
1,881
|
3,525
|
| Elimination and Consolidation Adjustments [Member] |
|
|
|
| Operating Activities |
|
|
|
| Net cash provided by operating activities |
0
|
0
|
0
|
| Investing Activities |
|
|
|
| Net transactions with affiliates |
0
|
0
|
0
|
| Capital expenditures |
0
|
0
|
0
|
| Cash paid for intangible assets |
0
|
0
|
0
|
| Acquisitions and construction of real estate properties |
0
|
0
|
0
|
| Acquisitions, net of cash acquired |
0
|
0
|
0
|
| Proceeds from sales of businesses and investments |
0
|
0
|
0
|
| Purchases of investments |
0
|
0
|
0
|
| Deposits |
0
|
0
|
0
|
| Other |
0
|
0
|
0
|
| Net cash provided by (used in) investing activities |
0
|
0
|
0
|
| Financing Activities |
|
|
|
| Proceeds from (repayments of) short-term borrowings, net |
0
|
0
|
0
|
| Proceeds from borrowings |
0
|
0
|
0
|
| Repurchases and repayments of debt |
0
|
0
|
0
|
| Repurchases and retirements of common stock |
0
|
0
|
0
|
| Dividends paid |
0
|
0
|
0
|
| Issuances of common stock |
0
|
0
|
0
|
| Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock |
0
|
0
|
0
|
| Other |
0
|
0
|
0
|
| Net cash provided by (used in) financing activities |
0
|
0
|
0
|
| Increase (decrease) in cash and cash equivalents |
0
|
0
|
0
|
| Cash and cash equivalents, beginning of year |
0
|
0
|
0
|
| Cash and cash equivalents, end of year |
$ 0
|
$ 0
|
$ 0
|