v3.6.0.2
Condensed Consolidating Financial Information (Condensed Consolidating Statement of Income) (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 $ 80,403 $ 74,510 $ 68,775
Management fee revenue                 0 0 0
Revenue $ 21,025 $ 21,319 $ 19,269 $ 18,790 $ 19,245 $ 18,669 $ 18,743 $ 17,853 80,403 74,510 68,775
Costs and Expenses:                      
Programming and production                 24,463 22,550 20,912
Other operating and administrative                 23,409 21,319 19,839
Advertising, marketing and promotion                 6,114 5,963 5,101
Depreciation                 7,464 6,781 6,337
Amortization                 2,094 1,899 1,682
Costs and expenses, total                 63,544 58,512 53,871
Operating income (loss) 4,264 4,440 4,066 4,089 4,002 4,001 4,105 3,890 16,859 15,998 14,904
Other Income (Expense):                      
Interest expense                 (2,942) (2,702) (2,617)
Investment income (loss), net                 213 81 296
Equity in net income (losses) of investees, net                 (104) (325) 97
Other income (expense), net                 327 320 (215)
Nonoperating Income (Expense)                 (2,506) (2,626) (2,439)
Income (loss) before income taxes                 14,353 13,372 12,465
Income tax (expense) benefit                 (5,308) (4,959) (3,873)
Net income (loss)                 9,045 8,413 8,592
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 (350) (250) (212)
Net income attributable to Parent $ 2,296 $ 2,237 $ 2,028 $ 2,134 $ 1,971 $ 1,996 $ 2,137 $ 2,059 8,695 8,163 8,380
Comprehensive income attributable to Parent                 8,967 8,135 8,178
Comcast Parent [Member]                      
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 0 0 0
Management fee revenue                 1,067 1,005 947
Revenue                 1,067 1,005 947
Costs and Expenses:                      
Programming and production                 0 0 0
Other operating and administrative                 813 760 751
Advertising, marketing and promotion                 0 0 0
Depreciation                 28 31 34
Amortization                 6 6 6
Costs and expenses, total                 847 797 791
Operating income (loss)                 220 208 156
Other Income (Expense):                      
Interest expense                 (1,941) (1,744) (1,621)
Investment income (loss), net                 7 6 3
Equity in net income (losses) of investees, net                 9,809 9,159 9,330
Other income (expense), net                 0 (3) 0
Nonoperating Income (Expense)                 7,875 7,418 7,712
Income (loss) before income taxes                 8,095 7,626 7,868
Income tax (expense) benefit                 600 537 512
Net income (loss)                 8,695 8,163 8,380
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 0 0 0
Net income attributable to Parent                 8,695 8,163 8,380
Comprehensive income attributable to Parent                 8,967 8,135 8,178
Comcast Holdings [Member]                      
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 0 0 0
Management fee revenue                 0 0 0
Revenue                 0 0 0
Costs and Expenses:                      
Programming and production                 0 0 0
Other operating and administrative                 0 0 0
Advertising, marketing and promotion                 0 0 0
Depreciation                 0 0 0
Amortization                 0 0 0
Costs and expenses, total                 0 0 0
Operating income (loss)                 0 0 0
Other Income (Expense):                      
Interest expense                 (12) (12) (11)
Investment income (loss), net                 (5) (1) 12
Equity in net income (losses) of investees, net                 9,286 8,651 8,843
Other income (expense), net                 0 0 0
Nonoperating Income (Expense)                 9,269 8,638 8,844
Income (loss) before income taxes                 9,269 8,638 8,844
Income tax (expense) benefit                 6 4 0
Net income (loss)                 9,275 8,642 8,844
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 0 0 0
Net income attributable to Parent                 9,275 8,642 8,844
Comprehensive income attributable to Parent                 9,317 8,625 8,807
CCCL Parent [Member]                      
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 0 0 0
Management fee revenue                 1,049 977 921
Revenue                 1,049 977 921
Costs and Expenses:                      
Programming and production                 0 0 0
Other operating and administrative                 1,049 977 921
Advertising, marketing and promotion                 0 0 0
Depreciation                 0 0 0
Amortization                 0 0 0
Costs and expenses, total                 1,049 977 921
Operating income (loss)                 0 0 0
Other Income (Expense):                      
Interest expense                 (239) (270) (294)
Investment income (loss), net                 0 0 0
Equity in net income (losses) of investees, net                 8,679 8,040 8,350
Other income (expense), net                 0 0 0
Nonoperating Income (Expense)                 8,440 7,770 8,056
Income (loss) before income taxes                 8,440 7,770 8,056
Income tax (expense) benefit                 84 94 103
Net income (loss)                 8,524 7,864 8,159
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 0 0 0
Net income attributable to Parent                 8,524 7,864 8,159
Comprehensive income attributable to Parent                 8,530 7,864 8,163
NBCUniversal Media Parent [Member]                      
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 0 0 0
Management fee revenue                 0 0 0
Revenue                 0 0 0
Costs and Expenses:                      
Programming and production                 0 0 0
Other operating and administrative                 932 922 908
Advertising, marketing and promotion                 0 0 0
Depreciation                 0 0 0
Amortization                 0 0 0
Costs and expenses, total                 932 922 908
Operating income (loss)                 (932) (922) (908)
Other Income (Expense):                      
Interest expense                 (456) (462) (479)
Investment income (loss), net                 (25) (19) (7)
Equity in net income (losses) of investees, net                 5,545 4,852 4,523
Other income (expense), net                 116 (31) (4)
Nonoperating Income (Expense)                 5,180 4,340 4,033
Income (loss) before income taxes                 4,248 3,418 3,125
Income tax (expense) benefit                 (13) (4) (10)
Net income (loss)                 4,235 3,414 3,115
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 0 0 0
Net income attributable to Parent                 4,235 3,414 3,115
Comprehensive income attributable to Parent                 4,312 3,361 2,972
Comcast Non-Guarantor Subsidiaries [Member]                      
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 80,403 74,510 68,775
Management fee revenue                 0 0 0
Revenue                 80,403 74,510 68,775
Costs and Expenses:                      
Programming and production                 24,463 22,550 20,912
Other operating and administrative                 22,731 20,642 19,127
Advertising, marketing and promotion                 6,114 5,963 5,101
Depreciation                 7,436 6,750 6,303
Amortization                 2,088 1,893 1,676
Costs and expenses, total                 62,832 57,798 53,119
Operating income (loss)                 17,571 16,712 15,656
Other Income (Expense):                      
Interest expense                 (294) (214) (212)
Investment income (loss), net                 236 95 288
Equity in net income (losses) of investees, net                 4,131 3,089 3,212
Other income (expense), net                 211 354 (211)
Nonoperating Income (Expense)                 4,284 3,324 3,077
Income (loss) before income taxes                 21,855 20,036 18,733
Income tax (expense) benefit                 (5,985) (5,590) (4,478)
Net income (loss)                 15,870 14,446 14,255
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 (350) (250) (212)
Net income attributable to Parent                 15,520 14,196 14,043
Comprehensive income attributable to Parent                 15,610 14,192 13,980
Elimination and Consolidation Adjustments [Member]                      
Condensed Income Statements, Captions [Line Items]                      
Service revenue                 0 0 0
Management fee revenue                 (2,116) (1,982) (1,868)
Revenue                 (2,116) (1,982) (1,868)
Costs and Expenses:                      
Programming and production                 0 0 0
Other operating and administrative                 (2,116) (1,982) (1,868)
Advertising, marketing and promotion                 0 0 0
Depreciation                 0 0 0
Amortization                 0 0 0
Costs and expenses, total                 (2,116) (1,982) (1,868)
Operating income (loss)                 0 0 0
Other Income (Expense):                      
Interest expense                 0 0 0
Investment income (loss), net                 0 0 0
Equity in net income (losses) of investees, net                 (37,554) (34,116) (34,161)
Other income (expense), net                 0 0 0
Nonoperating Income (Expense)                 (37,554) (34,116) (34,161)
Income (loss) before income taxes                 (37,554) (34,116) (34,161)
Income tax (expense) benefit                 0 0 0
Net income (loss)                 (37,554) (34,116) (34,161)
Net (income) loss attributable to noncontrolling interests and redeemable subsidiary preferred stock                 0 0 0
Net income attributable to Parent                 (37,554) (34,116) (34,161)
Comprehensive income attributable to Parent                 $ (37,769) $ (34,042) $ (33,922)