Schedule of Performance Obligation (Parenthetical) (Detail)	9 Months Ended
	Sep. 30, 2018
Hardware Products | Minimum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	30 days
Hardware Products | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	60 days
Software Licenses | Minimum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	30 days
Software Licenses | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	60 days
Professional Services | Minimum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	30 days
Professional Services | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	60 days
Software Maintenance and Support Services | Minimum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	30 days
Software Maintenance and Support Services | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	60 days
Extended Hardware Warranties | Minimum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	30 days
Extended Hardware Warranties | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Payment period, after shipment	60 days