Amount of expense related to estimated loss from loan and lease transactions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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Name:	us-gaap_ProvisionForLoanAndLeaseLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Mortgage Revenue Bonds - Additional Information (Details) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Provisions for credit loss				$ 7,318,590
Live 929 Apartments [Member]
Schedule Of Available For Sale Securities [Line Items]
Provisions for credit loss				3,500,000
Provision Center 2014-1 [Member]
Schedule Of Available For Sale Securities [Line Items]
Provisions for credit loss	$ 2,000,000.0	$ 465,000	$ 1,400,000	$ 3,900,000