Marketable Securities: Fair values of our marketable securities aggregated by credit rating (Details) - USD ($)	Jun. 30, 2023	Mar. 31, 2023
Marketable Securities	$ 53,187,406	$ 52,544,283
Standard & Poor's, AAA Rating
Marketable Securities	2,564,149
Standard & Poor's, AA Rating
Marketable Securities	6,626,736
Standard & Poor's, AA- Rating
Marketable Securities	20,804,539
Standard & Poor's, A+ Rating
Marketable Securities	7,893,562
Standard & Poor's, A Rating
Marketable Securities	9,387,766
Standard & Poor's, A- Rating
Marketable Securities	$ 5,910,654

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant