Equity - Summary of Dividends Paid Per Share (Detail) - $ / shares	6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Class A Common Stock [Member]
Class of Stock [Line Items]
Cash dividend paid per share	$ 0.10	$ 0.10
Class B Common Stock [Member]
Class of Stock [Line Items]
Cash dividend paid per share	$ 0.10	$ 0.10