Cash, Cash Equivalents, and Marketable Debt Securities - Schedule of Market Value of Marketable Debt Securities with Continuous Unrealized Losses (Details) - Fair Value of Marketable Debt Securities $ in Millions	Dec. 31, 2019 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Continuous Unrealized Losses, Less than 12 Months	$ 78.1
Continuous Unrealized Losses, Total	$ 78.1