Goodwill and Intangible Assets (Narrative) (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) Reporting_Unit	Sep. 30, 2018 USD ($)	Mar. 31, 2020	Mar. 31, 2019 USD ($)
Goodwill [Line Items]
Number of Reporting Units | Reporting_Unit			2
Amortization of intangibles	$ 3,226,000	$ 3,754,000	$ 6,479,000	$ 7,657,000
Goodwill	317,616,000		317,616,000			$ 322,816,000
Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year	13,000,000		13,000,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	13,000,000		13,000,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	13,000,000		13,000,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	13,000,000		13,000,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	13,000,000		13,000,000
Indefinite-Lived Trademarks	46,436,000		46,436,000			46,981,000
Goodwill, Impaired, Accumulated Impairment Loss	113,174,000		113,174,000			113,174,000
Rest of Products [Member]
Goodwill [Line Items]
Goodwill	308,037,000		308,037,000			313,205,000
Duff Norton Group [Member]
Goodwill [Line Items]
Goodwill	$ 9,579,000		$ 9,579,000			$ 9,611,000
Scenario, Forecast [Member]
Goodwill [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					18 years
Scenario, Forecast [Member] | Trademark
Goodwill [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					14 years
Scenario, Forecast [Member] | Customer relationships
Goodwill [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					18 years
Scenario, Forecast [Member] | Patented Technology [Member]
Goodwill [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					18 years
Scenario, Forecast [Member] | Other Intangible Assets [Member]
Goodwill [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life					6 years