Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 1,755	$ 1,491
Advertising expense	117	76	$ 61
Other operating costs	136	155	65
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 8	$ 14
Discontinued Operations, Disposed of by Means Other than Sale
Variable Interest Entity [Line Items]
Other operating costs			$ 19