Marketable Securities - Continuous Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 216,797
Gross Unrealized Losses	(85)
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	88,354
Gross Unrealized Losses	(32)
Municipal securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	3,671
Gross Unrealized Losses	(3)
U.S. Government agency securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	37,246
Gross Unrealized Losses	(13)
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	87,526
Gross Unrealized Losses	$ (37)