Share Capital, Option Plans and Share-Based Payments - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Cash Dividends
Dividends declared per common share (in dollars per share)	$ 0.1518	$ 0.1320
Payments of dividends	$ 40,466	$ 35,017
Share Capital
Preference shares issued (in shares)	0
Treasury Stock
Common shares repurchased (in shares)	304,000	0
Purchase of treasury stock	$ 11,719	$ 0
Issuance of treasury stock (in shares)	2,968	8,332

Aggregate dividends declared during the period for each share of common stock outstanding.

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The cash outflow to reacquire common stock during the period.

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