Fair Value Measurements - Schedule of Fair Value of Company's Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets
Total financial assets	$ 142,016	$ 73,411
Money market funds
Assets
Total financial assets	13,897	10,606
U.S. government securities
Assets
Total financial assets	77,400	9,975
Corporate notes
Assets
Total financial assets	14,966	16,499
Commercial paper
Assets
Total financial assets	35,753	36,331
Level 1
Assets
Total financial assets	13,897	10,606
Level 1 | Money market funds
Assets
Total financial assets	13,897	10,606
Level 1 | U.S. government securities
Assets
Total financial assets	0	0
Level 1 | Corporate notes
Assets
Total financial assets	0	0
Level 1 | Commercial paper
Assets
Total financial assets	0	0
Level 2
Assets
Total financial assets	128,119	62,805
Level 2 | Money market funds
Assets
Total financial assets	0	0
Level 2 | U.S. government securities
Assets
Total financial assets	77,400	9,975
Level 2 | Corporate notes
Assets
Total financial assets	14,966	16,499
Level 2 | Commercial paper
Assets
Total financial assets	35,753	36,331
Level 3
Assets
Total financial assets	0	0
Level 3 | Money market funds
Assets
Total financial assets	0	0
Level 3 | U.S. government securities
Assets
Total financial assets	0	0
Level 3 | Corporate notes
Assets
Total financial assets	0	0
Level 3 | Commercial paper
Assets
Total financial assets	$ 0	$ 0