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Investment in Silver Creek - Additional Information (Detail) - USD ($)
$ in Thousands
1 Months Ended 12 Months Ended
May 31, 2019
Dec. 31, 2019
Consolidation Less Than Wholly Owned Subsidiary Parent Ownership Interest Effects Of Changes Net [Line Items]    
Loss on equity method investment   $ 372
Proceeds from sales and maturities of marketable securities   51,500
Equity method investment realized gain loss on sale   1,400
Silver Creek Pharmaceuticals, Inc. [Member]    
Consolidation Less Than Wholly Owned Subsidiary Parent Ownership Interest Effects Of Changes Net [Line Items]    
Equity method investment   6,400
Loss on equity method investment   1,000
Proceeds from sales and maturities of marketable securities $ 7,800 $ 7,800