Payment Obligation Under 2009 Settlement Agreement (Detail) $ in Thousands	Dec. 31, 2020 USD ($)
Related Party Transaction [Line Items]
2021	$ 14,063
Total contractual payment obligation	14,075
Settlement Agreement
Related Party Transaction [Line Items]
2021	1,083
Present value discount factor	(43)
Total contractual payment obligation	$ 1,040

Amount of purchase arrangement to be paid in next fiscal year following current fiscal year. Includes, but is not limited to, recorded and unrecorded purchase obligations, long-term purchase commitment, and short-term purchase commitment. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

No definition available.

Name:	us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant