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Licensing and Other Arrangements - Zydus (Details) $ in Thousands		3 Months Ended
	Mar. 03, 2020 USD ($) item	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Licensing and other arrangements
Revenue from contracts with customers		$ 500	$ 8,026
Zydus \| License Agreement
Licensing and other arrangements
Maximum amount receivable milestone payments upon achievement of certain clinical development and regulatory approval events	$ 500
Maximum amount receivable upon achievement of commercial milestones	$ 23,500
Number of performance obligations \| item	1
Contract assets		0
Contract liabilities		0
Capitalized contract costs		0
Revenue from contracts with customers		$ 0