Earnings per share - Computation of earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income attributable to common shareholders	$ 411,248	$ 365,989	$ 1,098,696	$ 707,545
Denominator:
Basic - weighted average common shares (in shares)	128,706,137	133,032,431	130,476,355	133,107,321
Increase in weighted average common shares from dilutive effect of equity-based awards (in shares)	2,178,831	2,735,849	2,022,021	2,554,064
Diluted - weighted average common shares, assuming exercise of equity-based awards (in shares)	130,884,968	135,768,280	132,498,376	135,661,385
Basic earnings per share (in USD per share)	$ 3.20	$ 2.75	$ 8.42	$ 5.32
Diluted earnings per share (in USD per share)	$ 3.14	$ 2.70	$ 8.29	$ 5.22