Significant Transactions (Universal Studios Japan) (Details) - USD ($) $ in Millions		12 Months Ended
	Apr. 06, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Payments to acquire additional interest in noncontrolling interest		$ 0	$ 0	$ 2,299
NBCUniversal Media LLC [Member]
Business Acquisition [Line Items]
Payments to acquire additional interest in noncontrolling interest		$ 0	$ 0	$ 2,299
Universal Studios Japan [Member]
Business Acquisition [Line Items]
Payments to acquire additional interest in noncontrolling interest	$ 2,300
Universal Studios Japan [Member] | NBCUniversal Media LLC [Member]
Business Acquisition [Line Items]
Payments to acquire additional interest in noncontrolling interest	$ 2,300