XML 66 R67.htm IDEA: XBRL DOCUMENT
v3.20.1

Non-Marketable Investments - Additional Information (Detail) - USD ($) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2020 | Mar. 31, 2019 | Dec. 31, 2019
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items] |  |  |
Carrying value of the Company's non-marketable investments | $ 2,500,000 |  | $ 2,500,000
Distributions received from funds | $ 0 | $ 0 |
Limited Partnerships Investments [Member] | Minimum [Member] |  |  |
Fair Value Investments Entities That Calculate Net Asset Value Per Share [Line Items] |  |  |
Ownership interest of Company | 5.00% |  |

X
- Definition Carrying amount of investments in equity method investees and the carrying amount, after adjustment, of cost-method investments. + References No definition available. + Details
Name: | forr_CostAndEquityMethodInvestments
Namespace Prefix: | forr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Income received from cost and equity method investments funds during the period. + References No definition available. + Details
Name: | forr_CostMethodInvestmentOwnedIncomeReceivedFromFundDuringPeriod
Namespace Prefix: | forr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=118582676&loc=SL6759159-111685 + Details
Name: | us-gaap_VariableInterestEntityOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=forr_LimitedPartnershipsInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |