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Nature of Business and Overview (Details) $ in Thousands		3 Months Ended								12 Months Ended
Nature of Business and Overview (Details) $ in Thousands	Feb. 08, 2019	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Nature of Business and Overview
Reverse stock split	0.067
Cash, cash equivalents and marketable securities		$ 64,400								$ 64,400
Net Loss		(10,447)	$ (11,413)	$ (11,779)	$ (17,239)	$ (9,402)	$ (7,243)	$ (16,407)	$ (118,132)	(50,878)	$ (151,184)	$ (93,031)
Net cash used in operations										46,415	75,235	$ 99,931
Indefinite-lived intangible assets		$ 48,700				$ 48,700				$ 48,700	$ 48,700