Significant Transaction (Universal Studios Japan) (Details) - USD ($) $ in Millions		6 Months Ended
	Apr. 06, 2017	Jun. 30, 2017	Jun. 30, 2016
Business Acquisition [Line Items]
Payments to acquire additional interest in noncontrolling interest		$ 2,299	$ 0
NBCUniversal Media LLC [Member]
Business Acquisition [Line Items]
Payments to acquire additional interest in noncontrolling interest		$ 2,299	$ 0
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