Share Capital, Option Plans and Share-Based Payments - RSU's, DSU's and ESPP (Details) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	0	4,464	19,300
Award vesting period	3 years
Stock issued (in shares)	22,627	98,625	70,000
Stock issued	$ 0.7	$ 2.1	$ 1.5
Deferred Stock Units (DSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted (in shares)	100,271	87,501	91,680
Stock issued (in shares)	51,794	0	0
Stock issued	$ 2.0
Employee Share Purchase Plan (ESPP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards purchase price discount	15.00%
Common shares eligible for issuance (in shares)	696,091	729,521	530,170
Cash received from employee stock purchase plan	$ 22.2	$ 21.5	$ 14.8

Cash collected to be used to purchase Common Stock in future periods

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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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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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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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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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Aggregate value of stock related to Restricted Stock Awards issued during the period.

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