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Business Combinations and Asset Acquisitions - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Aug. 31, 2017
Purchase Price Allocation
Goodwill	$ 109	$ 109
Celgene Shanghai
Purchase Price Allocation
Cash and cash equivalents			$ 24,448
Other current assets			518
Property and equipment, net			204
Intangible assets			7,500
Deferred tax asset			1,069
Total identifiable assets			33,739
Current liabilities			(5,710)
Total liabilities assumed			(5,710)
Goodwill			109
Total fair value of consideration transferred			$ 28,138