Revenue Recognition - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
Mar. 31, 2019	Oct. 01, 2018
Revenue From Contract With Customer [Abstract]
Contract assets recorded in prepaid expenses and other current assets	$ 3.1	$ 2.7
Revenue remaining obligation description	As a practical expedient, since repair and maintenance service contracts have an original duration of one year or less, we do not consider the time value of money, and we do not disclose estimated revenue expected to be recognized in the future for performance obligations that are unsatisfied (or partially unsatisfied) at the end of the reporting period or when we expect to recognize such revenue.

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time, classified as current.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130533-203044

Name:	us-gaap_ContractWithCustomerAssetNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant