Share Capital, Option Plans and Share-Based Payments - Schedule of Weighted-Average Fair Value Of Options And Weighted-Average Assumptions Used (Details) - $ / shares	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted-average fair value of options granted (in dollars per share)	$ 7.58	$ 7.06	$ 5.69
Weighted-average assumptions used:
Expected volatility	26.95%	28.32%	31.76%
Risk–free interest rate	2.18%	1.46%	1.31%
Expected dividend yield	1.50%	1.43%	1.62%
Expected life (in years)	4 years 4 months 17 days	4 years 6 months 2 days	4 years 3 months 29 days
Forfeiture rate (based on historical rates)	6.00%	5.00%	5.00%
Average exercised share price (in dollars per share)	$ 34.60	$ 31.75	$ 24.09
Derived service period (in years)		1 year 9 months 15 days