Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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The cash outflow to reacquire common stock during the period.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of treasury shares (units) reissued during the period, excluding reissuance of shares (units) held in treasury used to satisfy equity-based compensation obligations exercised by the holders of such rights. Upon reissuance of shares (units) from treasury, either the common or preferred stock (unit) reissued is outstanding.

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Share Capital, Option Plans and Share-Based Payments - Long-Term Incentive Plans (Details) - USD ($)	3 Months Ended				6 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of treasury stock (in shares)	544,929		379,111		547,897	387,443
Purchase of treasury stock	$ 12,800,000		$ 0		$ 24,534,000	$ 0
Long Term Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of plan					3 years
Compensation cost related to unvested awards not yet recognized	$ 19,000,000.0				$ 19,000,000.0
Unvested stock awards compensation cost, weighted average recognition period					2 years 1 month 6 days
Fiscal 2018 LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of treasury stock (in shares)	539,103
Purchase of treasury stock	$ 13,800,000
Treasury Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of treasury stock (in shares)	545,000	3,000	379,000	9,000