Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 07, 2016	Dec. 14, 2015	Jan. 31, 2015	Nov. 30, 2014	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015	Jan. 22, 2016
Equity (Textual)
Dividends paid								$ 13,000	$ 43,200
Dividends paid per share in cash				$ 0.64	$ 0.68
Dividends declared, per share						$ 0.19	$ 0.18	$ 0.56	$ 1.85
Cost for contributions to the 401(k) Plan								$ 1,411	$ 1,300
Class A common stock [Member]
Equity (Textual)
Dividends paid per share in cash								$ 0.56	$ 1.85
Class A common stock [Member] | Subsequent Event [Member]
Equity (Textual)
Common stock dividends declared	$ 0.19
Paid date of declared dividend	Jun. 17, 2016
Record date of declared dividend	Jun. 13, 2016
Class B common stock [Member]
Equity (Textual)
Dividends paid per share in cash								$ 0.56	$ 1.85
Stock repurchase program, remaining number of shares authorized to be repurchased						8,000,000		8,000,000		4,600,000
Restricted Class B common stock purchased from employees, Shares						8,300,000		8,300,000		8,000,000
Number of options granted			100,000
Aggregate purchase price of shares repurchased								$ 4,600	$ 400
Class B common stock shares repurchased								398,376	29,675
Contribution of shares to 401(k) Plan								94,712	70,843
Class B common stock [Member] | Employees
Equity (Textual)
Aggregate purchase price of shares repurchased								$ 100	$ 300
Class B common stock shares repurchased								11,250	16,330
Class B common stock [Member] | Subsequent Event [Member]
Equity (Textual)
Common stock dividends declared	$ 0.19
Paid date of declared dividend	Jun. 17, 2016
Record date of declared dividend	Jun. 13, 2016
Decrease in outstanding stock option exercise price after spinoff		$ 2.25