Trade Receivables & Trade Receivables - Related Parties - Additional Information (Detail) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Accounts Receivable Net Current [Abstract]
Allowance for doubtful accounts	$ 0
Trade receivables	905,000	$ 973,000
Receivables from related parties	$ 2,307,000	$ 2,950,000

Amount of receivables arising from transactions with related parties due within one year or the normal operating cycle, if longer.

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Name:	us-gaap_AccountsReceivableRelatedPartiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant