Financial Instruments and Fair Value Measurements - Schedule of Marketable Securities (Details) $ in Millions	Dec. 31, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Amortized Cost	$ 148
Total Fair Value	148	[1]
Cash and Cash Equivalents	133
Short-Term Marketable Securities	15
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	128
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Fair Value	128	[1]
Cash and Cash Equivalents	128
Level 2 | Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total Amortized Cost	20
Total Fair Value	20	[1]
Cash and Cash Equivalents	5
Short-Term Marketable Securities	$ 15

[1] As of December 31, 2018, any unrealized gains or losses related to our marketable securities were not material.