Segment and Geographic Information - Revenue by Location and Product Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 151,551	$ 117,802
Power discrete
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	119,375	100,541
Power IC
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	29,455	15,724
Packaging and testing services
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,721	1,537
Hong Kong
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	126,600	93,102
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	23,209	16,512
South Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	136	5,990
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,456	1,101
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 150	$ 1,097