Segment and Geographic information - Revenue by Geographical Segment (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
Hong Kong
Segment Reporting Information [Line Items]
Revenue	383,411	355,058	340,178
China
Segment Reporting Information [Line Items]
Revenue	64,058	81,955	71,213
South Korea
Segment Reporting Information [Line Items]
Revenue	10,370	2,590	1,061
United States
Segment Reporting Information [Line Items]
Revenue	4,465	7,015	5,658
Other countries
Segment Reporting Information [Line Items]
Revenue	$ 2,605	$ 4,302	$ 3,443