Shareholders' Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		6 Months Ended
	Mar. 31, 2016	Feb. 27, 2016	Feb. 28, 2015
Components Of Shareholders Equity [Line Items]
Regular dividends cash paid		$ 52,948	$ 49,468
Cash dividends paid			234,871
Special dividends cash paid			$ 185,403
Dividends declared date		Mar. 31, 2016
Dividend payable date		Apr. 26, 2016
Dividends record date		Apr. 12, 2016
Purchase of treasury stock		$ 19,212
Subsequent Event [Member]
Components Of Shareholders Equity [Line Items]
Cash dividends paid	$ 26,390
Dividends payable per share	$ 0.43
Regular Dividends [Member]
Components Of Shareholders Equity [Line Items]
Cash dividends paid per common share		$ 0.86	$ 0.80
Regular dividends cash paid		$ 52,948	$ 49,468
Special Dividends [Member]
Components Of Shareholders Equity [Line Items]
Cash dividends paid per common share			$ 3.00
Special dividends cash paid			$ 185,403
Class A Treasury Stock [Member]
Components Of Shareholders Equity [Line Items]
Class A common stock shares repurchased		335
Purchase of treasury stock		$ 19,212
Shares repurchased by the company for associates' tax withholding liability associated with share-based compensation		36
Maximum number of shares that can be repurchased		1,444