Fair Value Measurements and Marketable Securities - Schedule of Financial Assets Measured and Recognized at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, amortized cost	$ 55,441	$ 66,350
Marketable securities, gross unrealized gains	70	69
Marketable securities, gross unrealized losses	(70)	(4)
Marketable securities, estimated fair value	55,441	66,415
Amortized Cost	90,902	100,358
Estimated Fair Value	90,902	100,423
U.S. Government Securities | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, amortized cost	19,995	24,973
Marketable securities, gross unrealized gains	59	32
Marketable securities, estimated fair value	20,054	25,005
Corporate Bonds | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, amortized cost	30,213	39,185
Marketable securities, gross unrealized gains	11	37
Marketable securities, gross unrealized losses	(70)	(4)
Marketable securities, estimated fair value	30,154	39,218
Commercial Paper | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities, amortized cost	5,233	2,192
Marketable securities, estimated fair value	5,233	2,192
Money Market Funds | Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Money market funds, amortized Cost	35,461	34,008
Money market funds, estimated Fair Value	$ 35,461	$ 34,008