Significant Accounting Policies - Summary of Changes in the Allowance for Doubtful Accounts (Details) - Allowance for Doubtful Accounts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance, beginning of period	$ 21	$ 16	$ 9
Charges to earnings	11	11	8
Write-offs, net of recoveries and other adjustments	(7)	(6)	(1)
Balance, end of period	$ 25	$ 21	$ 16