Accounting Policies - Video and Music Content (Details) - USD ($) $ in Billions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounting Policies [Abstract]
Weighted Average Life, Capitalized Video Content			2 years 7 months 6 days
Video and Music Content, Capitalized Costs	$ 5.0		$ 5.0		$ 3.8
Video and Music Content, Expense	$ 1.9	$ 1.7	$ 5.5	$ 4.9