Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands			6 Months Ended
	Oct. 17, 2018	Jan. 02, 2018	Apr. 30, 2019	Apr. 30, 2018	Oct. 31, 2018
Business Acquisition [Line Items]
Acquisition of businesses, net of cash acquired			$ 69	$ 44,176
Goodwill			$ 1,607,509		$ 1,608,018
Cladach Nua Teoranta [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Acquired percent of the outstanding shares	100.00%
Acquisition of businesses, net of cash acquired	$ 5,236
Acquisition of business, earn-out liability	1,131
Goodwill	3,776
Identifiable intangible assets	697
Cladach Nua Teoranta [Member] | Customer Relationships [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets	$ 58
Intangible assets amortization period	6 years
Cladach Nua Teoranta [Member] | Trade Names [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets	$ 70
Intangible assets amortization period	9 years
Cladach Nua Teoranta [Member] | Technology-Based Intangible Assets [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets	$ 499
Intangible assets amortization period	7 years
Cladach Nua Teoranta [Member] | Non-compete Agreements [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets	$ 70
Intangible assets amortization period	3 years
Sonoscan, Inc. [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Acquired percent of the outstanding shares		100.00%
Acquisition of businesses, net of cash acquired		$ 46,018
Goodwill		22,775
Identifiable intangible assets		7,910
Cash acquired from business acquisition		655
Sonoscan, Inc. [Member] | Customer Relationships [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets		$ 1,700
Intangible assets amortization period		7 years
Sonoscan, Inc. [Member] | Trade Names [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets		$ 3,300
Intangible assets amortization period		11 years
Sonoscan, Inc. [Member] | Technology-Based Intangible Assets [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets		$ 2,500
Intangible assets amortization period		7 years
Sonoscan, Inc. [Member] | Non-compete Agreements [Member] | 2018 Acquisition [Member]
Business Acquisition [Line Items]
Identifiable intangible assets		$ 410
Intangible assets amortization period		5 years