Regulatory authorities.

No definition available.

Name:	pjt_RegulatoryAuthoritiesLineItems
Namespace Prefix:	pjt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount of net capital in excess of minimum required net capital, calculated under Alternative Standard.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

Name:	srt_AlternativeExcessNetCapital
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Minimum amount of net capital of broker-dealer and its subsidiary, calculated under Alternative Standard.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

Name:	srt_AlternativeNetCapitalRequirement1
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of net capital of broker-dealer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

Indebtedness divided by net capital.

No definition available.

Name:	us-gaap_RatioOfIndebtednessToNetCapital1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Name:	srt_StatementGeographicalAxis=country_GB
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementGeographicalAxis=country_HK
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=pjt_ParkHillGroupLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=pjt_PJTPartnersLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Regulated Entities - Additional Information (Details) € in Thousands, $ in Thousands, $ in Millions	Jun. 30, 2019 USD ($)	Jun. 30, 2019 EUR (€)	Jun. 30, 2019 HKD ($)	Dec. 31, 2018 USD ($)
United Kingdom
Regulatory Authorities [Line Items]
Minimum net capital requirement \| €		€ 50
Hong Kong
Regulatory Authorities [Line Items]
Minimum net capital requirement			$ 3
Park Hill Group LLC
Regulatory Authorities [Line Items]
Minimum net capital requirement	$ 250
Percentage of aggregate indebtedness capital requirement	2	2	2
Net capital	$ 10,000			$ 15,000
Net capital in excess of required net capital	9,700			14,700
PJT Partners LP
Regulatory Authorities [Line Items]
Minimum net capital requirement	$ 100
Percentage of aggregate indebtedness capital requirement	6.67	6.67	6.67
Net capital	$ 17,700			10,600
Net capital in excess of required net capital	$ 16,800			$ 8,100
Maximum \| PJT Partners LP
Regulatory Authorities [Line Items]
Percentage of aggregate indebtedness capital requirement	15	15	15