Receivables - Receivables (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 6,333	$ 8,957
Allowance for bad debts	(26)	(26)
Receivables, net	6,307	8,931
Other receivables and accrued interest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	2,557	1,505
Loans secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables, gross	$ 3,776	$ 7,452
Average interest rates	5.40%	4.94%

Accounts and notes receivable gross.

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- Definition

Average interest rates.

+ References

No definition available.

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- Definition

Carrying amount as of the balance sheet date, net of allowance for doubtful accounts, of account and note receivables due from other than related parties.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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