Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22580-107794

Name:	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Revenue Recognition - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
	Oct. 31, 2018	Oct. 31, 2018	May 01, 2018	Apr. 30, 2018
Revenue Recognition [Line Items]
Contract assets and liabilities	$ 1,563,000	$ 1,563,000		$ 1,884,000
Contract liability recognized as revenue percentage	35.00%	81.00%
ASU 2014-09 [Member]
Revenue Recognition [Line Items]
Cumulative effect adjustment to increase retained earnings			$ 217,000
Fiscal Year 2019 [Member]
Revenue Recognition [Line Items]
Contract liability recognized as revenue percentage	100.00%