Accounting Policies - Video and Music Content (Details) - USD ($) $ in Billions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Accounting Policies [Abstract]
Weighted Average Life, Capitalized Video Content	2 years 7 months
Video and Music Content, Capitalized Costs	$ 4.2		$ 3.8
Video and Music Content, Expense	$ 1.7	$ 1.5