Segment and Geographic Information - Revenue by Location and Product Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 82,987	$ 76,918	$ 244,251	$ 246,463
Power discrete
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	63,464	59,181	182,769	185,275
Power IC
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	16,251	13,719	50,164	48,984
Packaging and testing services
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	3,272	4,018	11,318	12,204
Hong Kong
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	71,684	64,610	212,041	210,135
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	9,520	10,315	26,458	30,095
South Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	504	624	1,604	1,787
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	726	706	2,227	2,270
Other Countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 553	$ 663	$ 1,921	$ 2,176