Earnings Per Share - Additional Information (Detail) - shares	1 Months Ended	12 Months Ended			36 Months Ended
	Jul. 31, 2017	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016
Class of Stock [Line Items]
Number of shares authorized to be purchased (shares)		4,000,000,000,000
Repurchase of common stock (shares)		3,296,513			0
Remaining number of shares authorized to be repurchased		4,703,487
Antidilutive stock option (shares)		0	0	0
Class A Common Stock
Class of Stock [Line Items]
Percentage of shares outstanding used in two class method calculation		40.00%
Voting rights		The Class A Common Stock has no voting rights unless four quarterly cumulative dividends upon the Class A Common Stock are in arrears.
Repurchase of common stock (shares)		1,425,452
Class B Common Stock
Class of Stock [Line Items]
Percentage of shares outstanding used in two class method calculation		60.00%
Voting rights		The Class B Common Stock has full voting rights.
Number of shares authorized to be purchased (shares)		110,241
Repurchase of common stock (shares)	2,000	1,871,061