Investments (Available for sale equity investments) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022
Marketable Securities [Abstract]
Amortized coxt, equity investments	$ 55,631	$ 53,728
Estimated market value, equity investments	61,357	72,307
Common stocks [Member]
Marketable Securities [Abstract]
Amortized coxt, equity investments	29,577	27,674
Estimated market value, equity investments	39,375	46,212
Non-redeemable preferred stocks [Member]
Marketable Securities [Abstract]
Amortized coxt, equity investments	26,054	26,054
Estimated market value, equity investments	$ 21,982	$ 26,095

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(2))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI https://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

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