v2.4.0.8
Condensed Consolidating Financial Information (Condensed Consolidating Statement of Cash Flows) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Operating Activities      
Net cash provided by (used in) operating activities $ 14,160 $ 14,854 $ 14,345
Investing Activities      
Capital expenditures (6,596) (5,714) (5,307)
Cash paid for intangible assets (1,009) (923) (954)
Acquisitions of real estate properties (1,904)    
Acquisitions, net of cash acquired (99) (90) (6,407)
Proceeds from sales of businesses and investments 1,083 3,102 277
Return of capital from investees 149 2,362 37
Purchases of investments (1,223) (297) (135)
Other 85 74 (19)
Net cash provided by (used in) investing activities (9,514) (1,486) (12,508)
Financing Activities      
Proceeds from (repayments of) short-term borrowings, net 1,345 (544) 544
Proceeds from borrowings 2,933 4,544  
Repurchases and repayments of debt (2,444) (2,881) (3,216)
Repurchases and retirements of common stock (2,000) (3,000) (2,141)
Dividends paid (1,964) (1,608) (1,187)
Issuances of common stock 40 233 283
Purchase of NBCUniversal noncontrolling common equity interest (10,761)    
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock (215) (691) (325)
Settlement of Station Venture liability (602)    
Other (211) (90) (159)
Net cash provided by (used in) financing activities (13,879) (4,037) (6,201)
Increase (decrease) in cash and cash equivalents (9,233) 9,331 (4,364)
Cash and cash equivalents, beginning of year 10,951 1,620 5,984
Cash and cash equivalents, end of year 1,718 10,951 1,620
Comcast [Member]
      
Operating Activities      
Net cash provided by (used in) operating activities (600) (362) (513)
Investing Activities      
Net transactions with affiliates 66 3,845 4,615
Capital expenditures (7) (10) (7)
Cash paid for intangible assets (4) (6) (2)
Purchases of investments (11)    
Net cash provided by (used in) investing activities 44 3,829 4,606
Financing Activities      
Proceeds from (repayments of) short-term borrowings, net 1,349 (1) (4)
Proceeds from borrowings 2,933 2,536  
Repurchases and repayments of debt   (1,726) (1,095)
Repurchases and retirements of common stock (2,000) (3,000) (2,141)
Dividends paid (1,964) (1,608) (1,187)
Issuances of common stock 40 233 283
Other 198 99 51
Net cash provided by (used in) financing activities 556 (3,467) (4,093)
Comcast Holdings [Member]
      
Operating Activities      
Net cash provided by (used in) operating activities (3) (7) (19)
Investing Activities      
Net transactions with affiliates 3 206 19
Other   3  
Net cash provided by (used in) investing activities 3 209 19
Financing Activities      
Repurchases and repayments of debt   (202)  
Net cash provided by (used in) financing activities   (202)  
CCCL Parent [Member]
      
Operating Activities      
Net cash provided by (used in) operating activities (151) (177) (209)
Investing Activities      
Net transactions with affiliates 2,248 177 1,209
Net cash provided by (used in) investing activities 2,248 177 1,209
Financing Activities      
Repurchases and repayments of debt (2,097)   (1,000)
Net cash provided by (used in) financing activities (2,097)   (1,000)
Combined CCHMO Parents [Member]
      
Operating Activities      
Net cash provided by (used in) operating activities (94) (114) (131)
Investing Activities      
Net transactions with affiliates 332 667 131
Net cash provided by (used in) investing activities 332 667 131
Financing Activities      
Repurchases and repayments of debt (238) (553)  
Net cash provided by (used in) financing activities (238) (553)  
NBCUniversal Media Parent [Member]
      
Operating Activities      
Net cash provided by (used in) operating activities (1,102) (1,347) (638)
Investing Activities      
Net transactions with affiliates (470) 4,850 247
Acquisitions, net of cash acquired     295
Proceeds from sales of businesses and investments 2   3
Return of capital from investees 128    
Purchases of investments (3) (19) (4)
Other (20) (22)  
Net cash provided by (used in) investing activities (363) 4,809 541
Financing Activities      
Proceeds from (repayments of) short-term borrowings, net   (550) 550
Proceeds from borrowings   1,995  
Repurchases and repayments of debt (88) (2)  
Purchase of NBCUniversal noncontrolling common equity interest (3,200)    
Other (40) (14) (215)
Net cash provided by (used in) financing activities (3,328) 1,429 335
Increase (decrease) in cash and cash equivalents (4,793) 4,891 238
Cash and cash equivalents, beginning of year 5,129 238  
Cash and cash equivalents, end of year 336 5,129 238
Comcast Non-Guarantor Subsidiaries [Member]
      
Operating Activities      
Net cash provided by (used in) operating activities 16,110 16,861 15,855
Investing Activities      
Net transactions with affiliates (2,179) (9,745) (6,221)
Capital expenditures (6,589) (5,704) (5,300)
Cash paid for intangible assets (1,005) (917) (952)
Acquisitions of real estate properties (1,904)    
Acquisitions, net of cash acquired (99) (90) (6,702)
Proceeds from sales of businesses and investments 1,081 3,102 274
Return of capital from investees 21 2,362 37
Purchases of investments (1,209) (278) (131)
Other 105 93 (19)
Net cash provided by (used in) investing activities (11,778) (11,177) (19,014)
Financing Activities      
Proceeds from (repayments of) short-term borrowings, net (4) 7 (2)
Proceeds from borrowings 0 13  
Repurchases and repayments of debt (21) (398) (1,121)
Purchase of NBCUniversal noncontrolling common equity interest (7,561)    
Distributions to noncontrolling interests and dividends for redeemable subsidiary preferred stock (215) (691) (325)
Settlement of Station Venture liability (602)    
Other (369) (175) 5
Net cash provided by (used in) financing activities (8,772) (1,244) (1,443)
Increase (decrease) in cash and cash equivalents (4,440) 4,440 (4,602)
Cash and cash equivalents, beginning of year 5,822 1,382 5,984
Cash and cash equivalents, end of year $ 1,382 $ 5,822 $ 1,382