Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		9 Months Ended
	May 02, 2017	Apr. 10, 2017	Dec. 14, 2016	Jun. 30, 2017	Apr. 30, 2017	Apr. 30, 2017	Apr. 30, 2016	Jul. 31, 2016
Equity (Textual)
Class B common stock aggregate consideration						$ 10,000
Proceeds from exercise of stock options						835
Subsequent Event [Member]
Equity (Textual)
Fair value of options, Grant	$ 3,300,000
Subsequent Event [Member] | Jonas [Member]
Equity (Textual)
Options expire date	May 01, 2022
Class A common stock [Member]
Equity (Textual)
Dividends paid						$ 13,200	$ 13,000
Dividends paid per share in cash						$ 0.57	$ 0.56
Treasury shares					1,698,000	1,698,000		1,698,000
Class A common stock [Member] | Subsequent Event [Member]
Equity (Textual)
Common stock dividends declared				$ 0.19
Paid date of declared dividend				Jun. 30, 2017
Record date of declared dividend				Jun. 19, 2017
Class B common stock [Member]
Equity (Textual)
Dividends paid						$ 13,200	$ 13,000
Dividends paid per share in cash						$ 0.57	$ 0.56
Number of additional shares authorized			100,000
Treasury shares					3,297,000	3,297,000		3,931,000
Restricted Class B common stock purchased from employees, shares					8,000,000	8,000,000
Class B common stock shares repurchased							398,376
Aggregate purchase price of shares repurchased							$ 4,600
Stock repurchase program, remaining number of shares authorized to be repurchased					8,000,000	8,000,000
Class B common stock [Member] | 2015 Stock Option and Incentive Plan [Member]
Equity (Textual)
Stock issued for stock option exercises						73,471
Proceeds from exercise of stock options						$ 800
Class B common stock [Member] | Employee [Member]
Equity (Textual)
Class B common stock shares repurchased						94,338	11,250
Aggregate purchase price of shares repurchased						$ 1,800	$ 100
Class B common stock [Member] | Jonas [Member]
Equity (Textual)
Treasury shares of common stock sold					728,332
Closing price of Class B common stock		$ 13.73
Aggregate purchase price of shares repurchased					$ 10,000
Class B common stock [Member] | Subsequent Event [Member]
Equity (Textual)
Common stock dividends declared				$ 0.19
Paid date of declared dividend				Jun. 30, 2017
Record date of declared dividend				Jun. 19, 2017
Class B common stock [Member] | Subsequent Event [Member] | Jonas [Member]
Equity (Textual)
Class B common stock shares purchased options	1,000,000
Options exercise price	$ 14.93
Stock issued for stock option exercises	1,000,000
Class B common stock aggregate consideration	$ 14,930
Share price	$ 14.93
Repurchase right number of shares year 1	333,333
Repurchase right number of shares year 2	333,333
Repurchase right number of shares year 3	333,334