Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

The amount of income between the reporting entity and the Variable Interest Entity (VIE).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph d
-URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5747-111685

+ Details

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

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=whg_VariableInterestEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=whg_CommonTrustFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=whg_UndertakingForCollectiveInvestmentInTransferableSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Variable Interest Entities (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Investments in trading securities	$ 50,324	$ 65,781
Fee revenues from Westwood VIEs	31,000	46,100	$ 51,900
Variable Interest Entity [Member]
Variable Interest Entity [Line Items]
Investments in trading securities	6,400	$ 6,100
Common Trust Funds
Variable Interest Entity [Line Items]
Investments in trading securities	0
UCITS Fund
Variable Interest Entity [Line Items]
Investments in trading securities	$ 0