v3.6.0.2
Share-Based Compensation (Narrative) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation $ 233 $ 311 $ 299
Share-based compensation arrangement by share-based payment award, award vesting period in years 5 years    
NBCUniversal Media LLC [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation arrangement by share-based payment award, award vesting period in years 5 years    
Restricted Stock Units (RSUs) [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized pretax compensation expense on nonvested awards $ 712    
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years) 1 year 8 months    
Restricted Stock Units (RSUs) [Member] | NBCUniversal Media LLC [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized pretax compensation expense on nonvested awards $ 204    
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years) 1 year 11 months    
Employee Stock Option [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized pretax compensation expense on nonvested awards $ 375    
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years) 1 year 9 months    
Period from grant date that an equity-based award expires 10 years    
Employee Stock Option [Member] | NBCUniversal Media LLC [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Unrecognized pretax compensation expense on nonvested awards $ 28    
Unrecognized pretax compensation expense on nonvested awards, weighted average period of recognition (in years) 1 year 9 months    
Period from grant date that an equity-based award expires 10 years