Goodwill and Intangible Assets (Narrative) (Details) - USD ($)	3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Mar. 31, 2019	Mar. 31, 2018
Goodwill [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ 46,612,000			$ 46,612,000			$ 40,864,000
Amortization of intangibles	3,754,000		$ 3,920,000	7,657,000	$ 7,639,000
Goodwill	329,062,000			329,062,000			347,434,000
Impairment of Long-Lived Assets Held-for-use	0		$ 0	11,100,000	$ 0
Estimated amortization expense in 2019	15,000,000			15,000,000
Estimated amortization expense in 2020	15,000,000			15,000,000
Estimated amortization expense in 2021	15,000,000			15,000,000
Estimated amortization expense in 2022	15,000,000			15,000,000
Goodwill, Impaired, Accumulated Impairment Loss	113,174,000			113,174,000			107,000,000
Indefinite-Lived Trade Names	47,639,000			47,639,000
Rest of Products [Member]
Goodwill [Line Items]
Goodwill	319,413,000			319,413,000			337,713,000
Duff Norton Group [Member]
Goodwill [Line Items]
Goodwill	9,649,000			9,649,000			9,721,000
Trademark
Goodwill [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	4,123,000			4,123,000			3,299,000
Customer relationships
Goodwill [Line Items]
Impairment of Intangible Assets, Finite-lived				2,815,000
Finite-Lived Intangible Assets, Accumulated Amortization	30,972,000			30,972,000			27,887,000
Other Intangible Assets [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Finite-lived				226,000
Finite-Lived Intangible Assets, Accumulated Amortization	$ 2,546,000			2,546,000			$ 2,242,000
Other Intangible Assets [Member] | Reduced Depreciation [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Finite-lived				211,000
Customer relationships | Reduced Depreciation [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Finite-lived				957,000
Goodwill [Member]
Goodwill [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment		$ 6,174,000		$ 6,174,000
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