Significant Transactions (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 19, 2013
Significant Transactions [Line Items]
GE ownership percentage		49.00%
Purchase of NBCUniversal noncontrolling interest	$ 16,700,000,000
Payments related to acquisition of buildings	1,400,000,000
Preferred stock dividend rate percentage	5.25%
Deferred tax liabilities recognized associated with the redemption transaction	1,500,000,000
Cash On Hand
Significant Transactions [Line Items]
Total consideration transferred related to the Redemption Transaction and purchase of certain properties	11,400,000,000
NBCUniversal Enterprise Senior Unsecured Debt Securities
Significant Transactions [Line Items]
Total consideration transferred related to the Redemption Transaction and purchase of certain properties	4,000,000,000
Commercial Paper Program
Significant Transactions [Line Items]
Total consideration transferred related to the Redemption Transaction and purchase of certain properties	750,000,000
NBCUniversal Enterprise Credit Facility
Significant Transactions [Line Items]
Total consideration transferred related to the Redemption Transaction and purchase of certain properties	1,250,000,000
NBCUniversal Enterprise Preferred Stock
Significant Transactions [Line Items]
Total consideration transferred related to the Redemption Transaction and purchase of certain properties	$ 725,000,000