Share repurchase program (Details) - $ / shares	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Mar. 31, 2017	Oct. 22, 2014
Equity [Abstract]
Number of shares authorized to be repurchased (in shares)			35,000,000
Shares repurchased (in shares)	332,113	1,661,459
Shares repurchased, average price (in usd per share)	$ 150.55	$ 129.22