Bonds Payable (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Bonds	$ 210,695	$ 232,989
Less: unamortized deferred bond issuance costs	(7,503)	(9,724)
Total outstanding bonds, net	203,192	223,265
Bonds (Series A) [Member]
Bonds	69,747	92,653
Bonds (Series B) [Member]
Bonds	61,029	60,764
Bonds (Series C) [Member]
Bonds	$ 79,919	$ 79,572

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

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