Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company prepared the accompanying unaudited condensed consolidated and combined financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and the instructions to Form 10-Q. The condensed consolidated and combined financial statements, including these notes, are unaudited and exclude some of the disclosures required in audited financial statements. Management believes it has made all necessary adjustments (consisting of only normal recurring items) so that the condensed consolidated and combined financial statements are presented fairly and that estimates made in preparing its condensed consolidated and combined financial statements are reasonable and prudent. The operating results presented for interim periods are not necessarily indicative of the results that may be expected for any other interim period or for the entire year. These condensed consolidated and combined financial statements should be read in conjunction with the audited consolidated and combined financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015 filed with the SEC. For a comprehensive disclosure of the Company’s significant accounting policies, see Note 2. “Summary of Significant Accounting Policies” in the “Notes to Consolidated and Combined Financial Statements” in “Part II. Item 8. Financial Statements and Supplementary Data” in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. As the sole general partner of PJT Partners Holdings LP, PJT Partners Inc. operates and controls all of the business and affairs and consolidates the financial results of PJT Partners Holdings LP and its subsidiaries. The Company operates through the following subsidiaries: PJT Partners LP, Park Hill Group LLC, PJT Partners (UK) Limited and PJT Partners (HK) Limited. The Company did not operate as an independent, stand-alone entity for all periods included in these condensed consolidated and combined financial statements. Prior to the spin-off on October 1, 2015, the Company’s operations were included in Blackstone’s results as they were historically managed as part of Blackstone, in conformity with GAAP. For periods prior to October 1, 2015, the accompanying condensed consolidated and combined financial statements were prepared on a stand-alone basis and were derived from the consolidated financial statements and accounting records of Blackstone. Prior to October 1, 2015, the condensed consolidated and combined financial statements included certain assets that were historically held at the Blackstone corporate level but were specifically identifiable or otherwise attributable to these financial statements, primarily goodwill and intangible assets. Additionally prior to October 1, 2015, Blackstone’s net investment in PJT Partners is shown as Former Parent Company Investment in lieu of Stockholders’ Equity in the condensed consolidated and combined financial statements. All intercompany transactions have been eliminated for all periods presented. The Condensed Consolidated and Combined Statements of Operations reflect intercompany expense allocations made to the Company by Blackstone for certain corporate functions and for shared services provided by Blackstone prior to October 1, 2015. Where possible, these allocations were made on a specific identification basis and, in other cases, these expenses were allocated by Blackstone based on a pro rata basis of headcount, usage or some other basis depending on the nature of the allocated cost. Expenses without a specific consumption based indicator were allocated based on revenues adjusted for factors such as the size and complexity of the business. See Note 10. “Transactions with Related Parties” for further information on expenses allocated by Blackstone. Both the Company and Blackstone consider the basis on which the expenses were previously allocated to be a reasonable reflection of the utilization of services provided to or the benefit received by the Company during the periods presented prior to October 1, 2015. The allocations may not, however, reflect the expense the Company would have incurred as an independent, publicly traded company for the periods presented. Actual costs that may have been incurred if PJT Partners had been a stand-alone company would depend on a number of factors, including the chosen organizational structure, which functions were outsourced or performed by employees and strategic decisions made in areas such as information technology and infrastructure. Following the spin-off, the Company has been performing these functions using its own resources or purchased services. For an interim period, however, some of these functions may continue to be provided by Blackstone, pursuant to a transition services agreement for a period of 24 months with the option for Blackstone or the Company to terminate any given service with 60 days’ notice. See Note 10. “Transactions with Related Parties” for further information on services provided by Blackstone to the Company for the three and nine months ended September 30, 2016.
Contingencies and Litigation	Contingencies and Litigation The Company records loss contingencies if (a) information available prior to issuance of the condensed consolidated and combined financial statements indicates that it is probable that an asset had been impaired or a liability had been incurred at the date of the condensed consolidated and combined financial statements, and (b) the amount of loss can be reasonably estimated. If one or both criteria for accrual are not met, but there is at least a reasonable possibility that a loss will occur, the Company does not record an accrual for a loss contingency but describes the contingency and provides detail, when possible, of the estimated potential loss or range of loss. If an estimate cannot be made, a statement to that effect is made. Costs incurred with defending matters are expensed as incurred. Accruals related to loss contingencies are recorded in Other Expenses in the Condensed Consolidated and Combined Statements of Operations.
Insurance Reimbursements	Insurance Reimbursements Receipts from insurance reimbursements up to the amount of the losses recognized are considered recoveries. These recoveries are accounted for when they are probable of receipt. Insurance recoveries are not recognized prior to the recognition of the related loss. Any receivable for insurance recoveries is recorded separately from the corresponding liability, and only if recovery is determined to be probable and reasonably estimable. Insurance reimbursements are recorded in Other Expenses in the Condensed Consolidated and Combined Statements of Operations.
Recent Accounting Developments	Recent Accounting Developments In June 2014, the Financial Accounting Standards Board (“FASB”) issued amended guidance on revenue from contracts with customers. The guidance requires that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. An entity is required to (a) identify the contract(s) with a customer, (b) identify the performance obligations in the contract, (c) determine the transaction price, (d) allocate the transaction price to the performance obligations in the contract, and (e) recognize revenue when (or as) the entity satisfies a performance obligation. In determining the transaction price, an entity may include variable consideration only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized would not occur when the uncertainty associated with the variable consideration is resolved. The guidance introduces new qualitative and quantitative disclosure requirements about contracts with customers including revenue and impairments recognized, disaggregation of revenue and information about contract balances and performance obligations. Information is required about significant judgments and changes in judgments in determining the timing of satisfaction of performance obligations and determining the transaction price and amounts allocated to performance obligations. Additional disclosures are required about assets recognized from the costs to obtain or fulfill a contract. As originally proposed, the guidance was effective prospectively for annual periods beginning after December 15, 2016 including interim periods within that reporting period. In recent re-deliberations, the FASB approved a one-year deferral of the effective date of this guidance, such that it will be effective for annual reporting periods beginning after December 31, 2017, with early adoption permitted for annual periods beginning after December 15, 2016. The Company is currently evaluating the impact of the new guidance and the method of adoption on the condensed consolidated and combined financial statements. In September 2015, the FASB issued guidance on measurement period adjustments with respect to business combinations. The amendments apply to entities that have reported provisional amounts for items in a business combination for which the accounting is incomplete by the end of the reporting period in which the combination occurs and during the measurement period have an adjustment to provisional amounts recognized. An entity is now required to recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined, not on a retrospective basis as previously required. The amendments apply prospectively to adjustments to provisional amounts that occur in fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. Adoption of this guidance did not have a material impact on the Company’s condensed consolidated and combined financial statements. In February 2016, the FASB issued new guidance regarding leases. The guidance requires lessees to recognize, on the balance sheet, assets and liabilities for the rights and obligations created by leases. Entities are also required to provide enhanced disclosure about leasing arrangements. The amendments retain lease classifications, distinguishing finance leases from operating leases, using criteria that are substantially similar for distinguishing capital leases from operating leases in previous guidance. The guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018, with early adoption permitted. Adoption requires a modified retrospective approach. The Company is currently assessing the impact the adoption of this guidance will have on its condensed consolidated and combined financial statements. In March 2016, the FASB issued amendments to the guidance on employee share-based payment accounting intended to improve the accounting for employee share-based payments. This amended guidance simplifies several aspects of the accounting for share-based payment award transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification in the statement of cash flows. The amendments are effective for annual periods beginning after December 15, 2016, and interim periods within those annual periods. Early adoption is permitted. The Company elected to early adopt the new guidance in the second quarter of fiscal year 2016, which requires the Company to reflect any adjustments as of January 1, 2016, the beginning of the annual period that includes the interim period of adoption. The primary impact of the adoption was the recognition of excess tax benefits in the Company’s Provision for Taxes rather than Additional Paid-In Capital for all periods in the year ended December 31, 2016. As no excess tax benefits were previously recognized during the three months ended March 31, 2016, no adjustments are required to show the impact to the previously reported amounts in the Company’s Quarterly Report on Form 10-Q for the period ended March 31, 2016. Additionally, there were no previously unrecognized excess tax benefits. The Company elected to apply the presentation requirements for cash flows related to excess tax benefits retrospectively and prior periods have been adjusted to remove the amounts of excess tax benefits presented in operating and financing activities in the Condensed Consolidated and Combined Statements of Cash Flows. Such prior period adjustment was immaterial. Additionally, the Company has retrospectively included in financing activities on the Condensed Consolidated and Combined Statements of Cash Flows amounts for employee taxes paid in instances when the Company withheld shares for tax withholding purposes. The Company has elected to maintain its current accounting policy of estimating forfeitures in its computation of equity-based compensation expense. Upon the adoption of this guidance, the Company excluded the estimated impact of excess tax benefits and tax deficiencies from the calculation of assumed proceeds for determining diluted net income (loss) per share using the treasury stock method. There was no impact on net loss per share of Class A common stock. In June 2016, the FASB issued guidance regarding the measurement of credit losses on financial instruments. The new guidance replaces the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The guidance is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2018. The Company is currently assessing the impact the adoption of this guidance will have on its condensed consolidated and combined financial statements.