Auction Rate Securities - Significant Assumptions Used to Determine Fair Value of Auction Rate Securities (Detail)	9 Months Ended	12 Months Ended
	Jul. 31, 2015	Oct. 31, 2014
Schedule of Available-for-sale Securities
Libor plus stated yield	2.00%	2.00%
Yields	2.15%	2.15%
Minimum
Schedule of Available-for-sale Securities
Discount rates	0.41%	0.28%
Average expected lives	4 years	4 years
Maximum
Schedule of Available-for-sale Securities
Discount rates	2.00%	4.06%
Average expected lives	10 years	10 years