Change in Carrying Amount of goodwill By Reportable Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
May 31, 2016	May 31, 2015
Goodwill [Line Items]
Goodwill beginning balance	$ 1,215,688	$ 1,147,374
Acquisitions	29,762	27,833
SPHC reconsolidation		118,713
Translation adjustments	(25,820)	(78,232)
Goodwill ending balance	1,219,630	1,215,688
Industrial Segment
Goodwill [Line Items]
Goodwill beginning balance	467,949	521,528
Acquisitions	18,834	8,504
Translation adjustments	(19,755)	(62,083)
Goodwill ending balance	467,028	467,949
Specialty Segment
Goodwill [Line Items]
Goodwill beginning balance	174,686	50,630
Acquisitions	7,168	8,539
SPHC reconsolidation		118,713
Translation adjustments	(1,759)	(3,196)
Goodwill ending balance	180,095	174,686
Consumer Segment
Goodwill [Line Items]
Goodwill beginning balance	573,053	575,216
Acquisitions	3,760	10,790
Translation adjustments	(4,306)	(12,953)
Goodwill ending balance	$ 572,507	$ 573,053

Goodwill Acquired During Period And Adjustments

No definition available.

Name:	rpm_GoodwillAcquiredDuringPeriodAndAdjustments
Namespace Prefix:	rpm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

+ Details

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

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

+ Details

Name:	us-gaap_GoodwillForeignCurrencyTranslationGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_GoodwillLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=rpm_IndustrialSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=rpm_SpecialtySegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=rpm_ConsumerSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: