Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended			3 Months Ended		6 Months Ended
	Dec. 14, 2015	Mar. 31, 2016	Jan. 31, 2015	Nov. 30, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015	Jan. 22, 2016
Equity (Textual)
Dividends paid							$ 8.6	$ 38.9
Dividends paid per share in cash			$ 0.64	$ 0.68
Dividends declared, per share					$ 0.19	$ 0.82	$ 0.37	$ 1.67
Class A common stock [Member]
Equity (Textual)
Dividends paid per share in cash							0.37	1.67
Class A common stock [Member] | Subsequent Event [Member]
Equity (Textual)
Common stock dividends declared		$ 0.19
Paid date of declared dividend		Mar. 25, 2016
Record date of declared dividend		Mar. 15, 2016
Class B common stock [Member]
Equity (Textual)
Dividends paid per share in cash							$ 0.37	$ 1.67
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							$ 4.6	$ 0.4
Class B common stock shares repurchased							398,376	29,675
Class B common stock [Member] | Employees
Equity (Textual)
Aggregate purchase price of shares repurchased							$ 0.1	$ 0.3
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		Mar. 25, 2016
Record date of declared dividend		Mar. 15, 2016