Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value of Financial Instruments
Total assets measured at fair value	$ 219,158	$ 127,927
Money market funds
Fair Value of Financial Instruments
Money market funds	219,158	127,927
Level 1
Fair Value of Financial Instruments
Total assets measured at fair value	219,158	127,927
Level 1 \| Money market funds
Fair Value of Financial Instruments
Money market funds	$ 219,158	$ 127,927

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant