Consolidated Statements of Patronage Capital and Membership Fees (Unaudited) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Increase (Decrease) in Members' Capital
Net margin	$ 25,958	$ 23,204
Patronage Capital and Membership Fees
Increase (Decrease) in Members' Capital
Beginning balance	1,072,642	1,016,747
Net margin	25,958	23,204
Ending balance	$ 1,098,600	$ 1,039,951

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1377-109256

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration