Fair Value Measurements - Schedule of Unrealized Loss on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair value
Less than 12 months	$ 0	$ 67,217
12 months or greater	10,498	79,618
Total	10,498	146,835
Unrealized losses
Less than 12 months	0	(46)
12 months or greater	(5)	(45)
Total	(5)	(91)
U.S. government agency securities and treasuries
Fair value
Less than 12 months	0	13,234
12 months or greater	10,498	79,618
Total	10,498	92,852
Unrealized losses
Less than 12 months	0	(3)
12 months or greater	(5)	(45)
Total	$ (5)	(48)
Corporate bonds
Fair value
Less than 12 months		53,983
12 months or greater		0
Total		53,983
Unrealized losses
Less than 12 months		(43)
12 months or greater		0
Total		$ (43)