Subsequent events - Narrative (Details) (USD $)	12 Months Ended		0 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jul. 15, 2014 Subsequent Event [Member]	Jun. 30, 2014 Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends payable, date declared				Jul. 15, 2014
Common stock, dividends declared (in dollars per share)	$ 0.70	$ 0.70	$ 0.18	$ 0.70
Annual dividend rate per share (in dollars per share)			$ 0.72
Dividends payable, date of record				Aug. 15, 2014
Dividends payable, date to be paid				Aug. 29, 2014