Earnings per share - Computation of earnings per share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income attributable to common shareholders	$ 367,253	$ 411,248	$ 910,625	$ 1,098,696
Denominator:
Basic - weighted average common shares (in shares)	128,289,720	128,706,137	128,383,549	130,476,355
Increase in weighted average common shares from dilutive effect of equity-based awards (in shares)	1,456,827	2,178,831	1,479,266	2,022,021
Diluted - weighted average common shares, assuming exercise of equity-based awards (in shares)	129,746,547	130,884,968	129,862,815	132,498,376
Basic earnings per share (in USD per share)	$ 2.86	$ 3.20	$ 7.09	$ 8.42
Diluted earnings per share (in USD per share)	$ 2.83	$ 3.14	$ 7.01	$ 8.29