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Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands			6 Months Ended
	Mar. 05, 2018	Dec. 14, 2017	Jan. 31, 2018	Jan. 31, 2017	Oct. 31, 2016
Equity (Textual)
Dividends paid per share in cash			$ 0.38
Proceeds from exercise of stock options				$ 835
Common Stock [Member]
Equity (Textual)
Aggregate dividends paid on common stock including Class A and Class B.			$ 9,400		$ 8,800
Common Class A [Member]
Equity (Textual)
Dividends paid per share in cash			$ 0.38		$ 0.38
Common Class A [Member] \| Subsequent Event [Member]
Equity (Textual)
Dividends paid per share in cash	$ 0.09
Paid date of declared dividend	Mar. 23, 2018
Record date of declared dividend	Mar. 19, 2018
Common Class B [Member]
Equity (Textual)
Dividends paid per share in cash			$ 0.38	$ 0.38
Class B common stock shares purchased options			8,000,000
Stock repurchase program, remaining number of shares authorized to be repurchased			8,000,000
Common Class B [Member] \| Subsequent Event [Member]
Equity (Textual)
Dividends paid per share in cash	$ 0.09
Paid date of declared dividend	Mar. 23, 2018
Record date of declared dividend	Mar. 19, 2018
Common Class B [Member] \| Employee [Member]
Equity (Textual)
Aggregate purchase price of shares repurchased			$ 100	$ 1,800
Class B common stock shares repurchased			5,170	94,338
Common Class B [Member] \| 2015 Stock Option and Incentive Plan [Member]
Equity (Textual)
Additional shares available stock option incentive plan for grants		300,000
Proceeds from exercise of stock options				$ 800,000
Stock issued for stock option exercises				73,471