Note 16 - Employee Benefit Plans - Company's Participation in Multiemployer Pension Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Contributions	$ 1,126	$ 1,105	$ 1,120
New England Teamsters and Trucking Industry Pension Fund [Member]
Contributions	531	461	482
IAM National Pension Fund National Pension Plan [Member]
Contributions	$ 595	$ 644	$ 638

Amount of cost for employer contribution to multiemployer plan. Multiemployer plan includes, but is not limited to, pension plan determined to be individually significant and insignificant and other postretirement benefit plan.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=35742348&loc=SL14450788-114948

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 35
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=29639808&loc=d3e29008-114946

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450691-114947

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