Segment and Geographic information - Revenue by Product Type (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Revenue	$ 464,909	$ 450,920	$ 421,553
Power discrete
Segment Reporting Information [Line Items]
Revenue	391,941	371,837	342,148
Power IC
Segment Reporting Information [Line Items]
Revenue	66,360	70,215	67,083
Packaging and testing services
Segment Reporting Information [Line Items]
Revenue	$ 6,608	$ 8,868	$ 12,322