Long-Term Debt	6 Months Ended
Long-Term Debt	Jun. 30, 2017
Debt Instrument [Line Items]
Long-Term Debt	Long-Term Debt As of June 30, 2017, our debt had a carrying value of $63.6 billion and an estimated fair value of $70.3 billion. The estimated fair value of our publicly traded debt was primarily based on Level 1 inputs that use quoted market values for the debt. The estimated fair value of debt for which there are no quoted market prices was based on Level 2 inputs that use interest rates available to us for debt with similar terms and remaining maturities. Debt Borrowings and Repayments In June 2017, NBCUniversal Enterprise issued $1.5 billion aggregate principal amount of senior floating rate notes due 2021. In March 2017, we issued $1.005 billion aggregate principal amount of 4.45% senior notes due 2047. In January 2017, we issued $1.25 billion aggregate principal amount of 3.00% senior notes due 2024 and $1.25 billion aggregate principal amount of 3.30% senior notes due 2027. In May 2017, we repaid at maturity $550 million aggregate principal amount of 8.875% senior notes due 2017. In January 2017, we repaid at maturity $1.0 billion aggregate principal amount of 6.50% senior notes due 2017. In May 2017, Universal Studios Japan entered into a new ¥450 billion ($3.9 billion at issuance) term loan with a final maturity of March 2022. We used the proceeds from this borrowing to repay in full $3.3 billion of Universal Studios Japan’s existing yen-denominated term loans and a portion of amounts outstanding under our commercial paper program. Revolving Credit Facilities As of June 30, 2017, amounts available under our consolidated revolving credit facilities, net of amounts outstanding under our commercial paper programs and outstanding letters of credit, totaled $7.2 billion, which included $1.5 billion available under NBCUniversal Enterprise’s revolving credit facility. Commercial Paper Programs In June 2017, we increased the Comcast and NBCUniversal Enterprise commercial paper programs to $7.0 billion and $1.5 billion, respectively, to coincide with the Comcast and NBCUniversal Enterprise revolving credit facilities’ commitments. As of June 30, 2017, Comcast had $1.1 billion face amount of commercial paper outstanding and NBCUniversal Enterprise had no commercial paper outstanding.
NBCUniversal Media LLC [Member]
Debt Instrument [Line Items]
Long-Term Debt	Long-Term Debt As of June 30, 2017, our debt, excluding the note payable to Comcast, had a carrying value of $12.3 billion and an estimated fair value of $13.5 billion. The estimated fair value of our publicly traded debt was primarily based on Level 1 inputs that use quoted market values for the debt. The estimated fair value of debt for which there are no quoted market prices was based on Level 2 inputs that use interest rates available to us for debt with similar terms and remaining maturities. In May 2017, Universal Studios Japan entered into a new ¥450 billion ($3.9 billion at issuance) term loan with a final maturity of March 2022. We used the proceeds from this borrowing to repay in full $3.3 billion of Universal Studios Japan’s existing yen-denominated term loans and a portion of amounts outstanding under our revolving credit agreement with Comcast. Cross-Guarantee Structure We, Comcast and a 100% owned cable holding company subsidiary of Comcast (“CCCL Parent”) have fully and unconditionally guaranteed each other’s debt securities, including the $7 billion Comcast revolving credit facility due 2021. As of June 30, 2017, outstanding debt securities of $46.1 billion of Comcast and CCCL Parent were subject to the guarantee structure. We do not, however, guarantee the obligations of NBCUniversal Enterprise with respect to its $4.8 billion aggregate principal amount of senior notes, $1.5 billion revolving credit facility, commercial paper program, or $725 million liquidation preference of Series A cumulative preferred stock. The Universal Studios Japan term loan is not subject to the cross-guarantee structure, however it has a separate guarantee from Comcast.