Long-Term Debt And Short-Term Borrowings (Narrative) (Details) € in Millions, AUD in Millions			9 Months Ended
	Jun. 30, 2020	Jun. 30, 2017	Sep. 30, 2017 USD ($)	Jan. 27, 2017 USD ($)	Jan. 27, 2017 EUR (€)	Jan. 27, 2017 AUD	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Total debt			$ 1,041,900,000				$ 703,500,000
Secured Debt | Euro Term Loan A
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 320,800,000	€ 300.0
Secured Debt | AUD Term Loan A
Debt Instrument [Line Items]
Maximum borrowing capacity				60,400,000		AUD 80.0
Secured Debt | Australian Dollar Senior Secured Term Loan A, due April 2020 (floating interest rate of 3.25% at December 31, 2016)
Debt Instrument [Line Items]
Total debt			0				70,300,000
Secured Debt | Australian Dollar Senior Secured Revolving Credit Facility, due April 2020 (floating interest rate of 3.27% at December 31, 2016)
Debt Instrument [Line Items]
Total debt			$ 0				$ 87,900,000
2017 Revolving Facility | Secured Debt
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 400,000,000
Commitment fee percent			0.30%
Total debt			$ 237,000,000
Amount available for borrowings under Senior Secured Revolving Credit Facilities			151,100,000
Letters of credit outstanding			$ 11,900,000
Senior Secured Credit Facility Due January 2022 | AUD Term Loan A
Debt Instrument [Line Items]
Proceeds from sales or dispositions of property or assets, percentage			100.00%
Senior Secured Credit Facility Due January 2022 | Secured Debt
Debt Instrument [Line Items]
Proceeds from sales or dispositions of property or assets			$ 12,000,000
Proceeds from sales or dispositions of property or assets, percentage			100.00%
Dividends and/or repurchase shares, threshold			$ 30,000,000
Dividends and/or repurchase shares, threshold, percent of total assets			1.00%
Minimum leverage ratio for payment of dividends or repurchase of shares			2.50
Maximum leverage ratio for payment of dividends or repurchase of shares			3.75
Leverage ratio, potential increase			0.50
Maximum borrowing capacity, potential increase			$ 500,000,000
Minimum | Secured Debt | Senior Secured Term Loan As, due January 2022
Debt Instrument [Line Items]
Quarterly installment, percentage of principal		5.00%
Minimum | 2017 Revolving Facility | Secured Debt
Debt Instrument [Line Items]
Commitment fee percent			0.25%
Minimum | Senior Secured Credit Facility Due January 2022 | Secured Debt
Debt Instrument [Line Items]
Fixed charge coverage ratio			1.25
Maximum | 2017 Revolving Facility | Secured Debt
Debt Instrument [Line Items]
Commitment fee percent			0.40%
Maximum | Senior Secured Credit Facility Due January 2022 | Secured Debt
Debt Instrument [Line Items]
Dividends and/or repurchase shares, threshold			$ 75,000,000
Leverage ratio			3.75
Maximum | Scenario, Forecast | Secured Debt | Senior Secured Term Loan As, due January 2022
Debt Instrument [Line Items]
Quarterly installment, percentage of principal	12.50%
≤ 3.50 to 1.00 and 3.00 to 1.00 | Euro/AUD/CDN | Senior Secured Credit Facility Due January 2022 | Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			2.00%
≤ 3.50 to 1.00 and 3.00 to 1.00 | Base Rate | Senior Secured Credit Facility Due January 2022 | Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			1.00%