Note 7 - Pension, Postretirement and Postemployment Defined Benefit Plans (Details Textual)		3 Months Ended		6 Months Ended
	Mar. 29, 2020 USD ($)	Mar. 29, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 29, 2020 USD ($)	Mar. 31, 2019 USD ($)	Mar. 16, 2020 USD ($)
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total		$ (8,000)	$ (109,000)	$ 70,000	$ (218,000)
Defined Benefit Plan, Plan Assets, Contributions by Employer				0
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year	$ 6,720,000	$ 6,720,000		$ 6,720,000
BHMG [Member] | Pension Plan [Member]
Defined Benefit Plan, Benefit Obligation, Ending Balance						$ 43,503,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	(86,000)
BHMG [Member] | Postemployment Retirement Benefits [Member]
Defined Benefit Plan, Benefit Obligation, Ending Balance						$ 36,800,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	$ (79,000)
Defined Benefit Plan, Collective Bargaining Units						8
Defined Benefit Plan, Collective Bargaining Units, Capped Premiums						5
Defined Benefit Plan, Collective Bargaining Units, Uncapped Premiums						3