Share Capital, Option Plans and Share-Based Payments - RSU's, DSU's and ESPP (Details) - USD ($)	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of treasury stock (in shares)	379,111	341,588	387,443	349,922
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares)	1,496	0	4,464	7,800
Award vesting period			3 years
Issuance of treasury stock (in shares)	66,460	1,666	74,792	10,000
Stock issued	$ 1,400,000	$ 20,500	$ 1,600,000	$ 100,000
Deferred Stock Units (DSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares)	77,606	73,254	80,809	75,696
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)	146,248	116,224	338,617	219,856
Cash received from employee stock purchase plan	$ 4,400,000	$ 3,300,000	$ 10,100,000	$ 6,200,000