Revenue recognition - Revenue by geographic region (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts	$ 3,411,905	$ 3,497,974	$ 6,642,445	$ 6,832,485
North America
Disaggregation of Revenue [Line Items]
Revenues from contracts	2,147,822	2,344,338	4,243,987	4,600,089
Europe
Disaggregation of Revenue [Line Items]
Revenues from contracts	682,960	652,586	1,298,532	1,291,724
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues from contracts	539,953	463,840	1,025,101	861,554
Latin America
Disaggregation of Revenue [Line Items]
Revenues from contracts	$ 41,170	$ 37,210	$ 74,825	$ 79,118