Earnings Per Share - Reconciliation of Shares Used to Calculate Basic and Diluted Earnings Per Share (Detail) - shares	3 Months Ended								12 Months Ended
	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2014
Class A Common Stock
Class of Stock [Line Items]
Basic (shares)	25,781,791	25,781,146	25,761,733	25,697,512	25,693,564	25,692,973	25,678,393	25,607,886	25,755,545	25,668,204	25,547,650
Assumed conversion of stock options (shares)									1,348	5,901	5,336
Diluted (shares)	25,785,266	25,783,184	25,766,609	25,704,023	25,701,264	25,698,547	25,688,653	25,617,814	25,756,893	25,674,105	25,552,986
Class B Common Stock
Class of Stock [Line Items]
Basic (shares)	22,009,725	22,009,725	22,108,942	22,119,966	22,119,966	22,119,966	22,119,966	22,119,966	22,100,000	22,100,000	22,100,000
Diluted (shares)	22,009,725	22,009,725	22,108,942	22,119,966	22,119,966	22,119,966	22,119,966	22,119,966	22,100,000	22,100,000	22,100,000
Basic and diluted shares									22,062,089	22,119,966	22,119,966