Accounting Policies - Video and Music Content (Details) - USD ($) $ in Billions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Accounting Policies [Abstract]
Weighted Average Life, Capitalized Video Content			2 years 6 months
Video and Music Content, Capitalized Costs	$ 4.6		$ 4.6		$ 3.8
Video and Music Content, Expense	$ 1.8	$ 1.6	$ 3.5	$ 3.2