Note 9 - Assets Held for Sale (Details Textual) - Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] - Purchase Agreement [Member] - USD ($) $ in Millions	3 Months Ended	24 Months Ended
May 31, 2016	May 31, 2018
Scenario, Forecast [Member]
Discontinued Operation, Amount of Continuing Cash Flows after Disposal		$ 10
Proceeds from Divestiture of Businesses, Net of Cash Divested	$ 165
Discontinued Operation, Period of Continuing Involvement after Disposal	2 years

Amount of cash inflow (outflow) from (to) the discontinued operation after the disposal transaction.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721665-107760

+ Details

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

- Definition

Period of expected continuing involvement with a discontinued operation after the disposal date, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721665-107760

+ Details

Name:	us-gaap_DiscontinuedOperationPeriodOfContinuingInvolvementAfterDisposal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the cash inflow during the period from the sale of a component of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

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

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=fds_PurchaseAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: