CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Collaboration revenue	$ 441	$ 1,602	$ 1,103	$ 4,126
Operating expenses:
Research and development	25,691	13,394	69,056	31,667
General and administrative	6,038	3,843	16,431	12,213
Total operating expenses	31,729	17,237	85,487	43,880
Loss from operations	(31,288)	(15,635)	(84,384)	(39,754)
Other income:
Interest income	1,661	1,487	4,635	2,963
Total other income	1,661	1,487	4,635	2,963
Net loss	$ (29,627)	$ (14,148)	$ (79,749)	$ (36,791)
Net loss per share-basic and diluted	$ (0.67)	$ (0.38)	$ (1.92)	$ (1.42)
Weighted-average common shares outstanding-basic and diluted	43,904,812	37,273,402	41,503,545	25,849,608

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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