Revenue Recognition - Capitalized Contract Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Contract Acquisition Costs
Capitalized Contract Cost [Roll Forward]
Beginning of period balance	$ 64	$ 13
Costs incurred	60	68
Amortization	(45)	(17)
End of period balance	79	64
Contract Fulfillment Costs
Capitalized Contract Cost [Roll Forward]
Beginning of period balance	84	14
Costs incurred	103	99
Amortization	(66)	(29)
End of period balance	$ 121	$ 84