Financial Instruments and Fair Value Measurements - Schedule of Fair Value of Assets and Liabilities Measured on Recurring Basis (Details) - Fair Value Measurements on Recurring Basis [Member] - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Cash Equivalents and Marketable Securities
Total cash equivalents	$ 449,873	$ 151,750
Money Market Funds [Member]
Cash Equivalents and Marketable Securities
Total cash equivalents	449,873	151,750
Quoted Price in Active Market (Level 1) [Member]
Cash Equivalents and Marketable Securities
Total cash equivalents	449,873	151,750
Quoted Price in Active Market (Level 1) [Member] | Money Market Funds [Member]
Cash Equivalents and Marketable Securities
Total cash equivalents	$ 449,873	$ 151,750