Related Party Disclosures (Detail) - USD ($) $ in Thousands		2 Months Ended	12 Months Ended
	Oct. 01, 2018	Nov. 23, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Payments to acquire additional interest in subsidiaries			$ 704	$ 262	$ 0
TxCell S.A.
Related Party Transaction [Line Items]
Number of ordinary shares acquired (in shares)	13,519,036	11,528,635
TxCell S.A. | Share Purchase Agreement and Tender Offer Agreement
Related Party Transaction [Line Items]
Number of ordinary shares acquired (in shares)			322,000	111,000	25,047,671
Payments to acquire additional interest in subsidiaries			$ 700	$ 300
Former Executive of TxCell | TxCell S.A. | Share Purchase Agreement and Tender Offer Agreement
Related Party Transaction [Line Items]
Number of ordinary shares acquired (in shares)			185,400	52,700
Payments to acquire additional interest in subsidiaries			$ 400	$ 100