Related Party Transactions	12 Months Ended
Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	14. RELATED PARTY TRANSACTIONS Employee Loans The Company periodically extends short term loans or advances to employees, typically upon commencement of employment. Total receivables as a result of these employee advances of $0.2 million existed at December 31, 2018 and 2017, respectively, and are included in the Prepaid expenses and other current assets and Other assets line items of the consolidated balance sheets, respectively, depending on the contractual repayment date. Management Fees In conjunction with the IPO, the Advisory Services Agreement with Cinven Capital Management (V) General Partner Limited (“Cinven”) expired. Subsequent to the IPO, the Company paid fees for director services provided by Cinven employees that were members of the Company’s Board of Directors and any related committees. The director fees were paid directly to Cinven in accordance with the Company’s non-employee director compensation policy. During the third quarter of 2018, Cinven sold its remaining shares of the Company’s common stock and all three members of the Company’s Board affiliated with Cinven subsequently resigned. During the year ended December 31, 2016, the Company incurred management fees to Cinven of $0.2 million. During the years ended December 31, 2018 and 2017, the Company incurred director fees of $0.1 million, respectively. In connection with these fees, Cinven incurred related travel expenses of less than $0.1 million, $0.1 million and $0.1 million, respectively, during the years ended December 31, 2018, 2017 and 2016. Service Agreements Coherus BioSciences, Inc. (“Coherus”) and MX II Associates, LLC (“MXII”) The chief executive officer of the Company was a member of Coherus BioSciences, Inc.’s (“Coherus”) board of directors until his resignation in the first quarter of 2018. Coherus is no longer considered a related party as of the first quarter of 2018. During 2011 a related party of the Company in which the Company’s chief executive officer is the managing member, MXII, made an investment in Coherus. In early 2012 the Company made a $2.5 million investment in Coherus. Concurrent with the initial investment, MXII secured the exclusive rights for Medpace to perform Phase I through Phase III clinical trial work for certain Coherus’ “bio-similar” drug compounds executed through a MSA. The agreement provides for a minimum fee commitment for clinical trial services and is cancelable without cause by either party upon 30 days prior notice. During the years ended December 31, 2017 and 2016, the Company recognized service revenue of $8.0 million and $22.3 million from Coherus in the Company’s consolidated statements of operations, respectively. In addition, the company recognized Reimbursed out-of-pocket revenue and Reimbursed out-of-pocket expenses with Coherus in the consolidated statements of operations of $1.3 million and $5.1 million during the years ended December 31, 2017 and 2016, respectively. As of December 31, 2017, the Company had Accounts receivable and unbilled, net from Coherus of $0.3 million recorded in the consolidated balance sheets. In addition, the Company had Advanced billings of $1.5 million and Pre-funded study costs of $1.0 million with Coherus recorded in the consolidated balance sheets at December 31, 2017. Xenon Pharmaceuticals, Inc. (“Xenon”) Certain executives and employees of the Company, including the chief executive officer, have held equity investments in Xenon, a clinical-stage biopharmaceutical company. In addition, a Medpace employee was a director of Xenon until May 2015. During the second quarter of 2017, the chief executive officer sold his entire equity position held in Xenon. Xenon is no longer considered to be a related party subsequent to this sale. During July 2015 the Company and Xenon entered into an amended MSA agreement for the Company to provide clinical trial related services. The Company recognized service revenue from Xenon of $0.6 million and $1.3 million during the six months ended June 30, 2017 and the year ended December 31, 2016, respectively, in the Company’s consolidated statements of operations. In addition, the Company recognized Reimbursed out-of-pocket revenue and Reimbursed out-of-pocket expenses with Xenon in the consolidated statements of operations of $0.1 million and $0.2 million during the six months ended June 30, 2017 and the year ended December 31, 2016, respectively. Cymabay Therapeutics, Inc. (“Cymabay”) Cymabay is a clinical-stage biopharmaceutical company developing therapies to treat metabolic diseases with high unmet medical need, including serious rare and orphan disorders. During the first quarter of 2016, it was announced that a Medpace employee would join Cymabay’s board of directors. The Company and Cymabay entered into a MSA dated October 21, 2016. Subsequently, the Company and Cymabay have entered into several task orders for the Company to perform clinical trial related services. The Company recognized total revenue from Cymabay of $10.8 million during the year ended December 31, 2018 in the Company’s consolidated statements of operations. The Company recognized service revenue from Cymabay of $0.6 million and $0.3 million during the years ended December 31, 2017 and 2016, respectively, in the Company’s consolidated statements of operations. As of December 31, 2018 and 2017, the Company had Accounts receivable and unbilled, net from Cymabay of $2.5 million and $0.1 million recorded in the consolidated balance sheets, respectively. LIB Therapeutics LLC and subsidiaries (“LIB”) Certain executives and employees of the Company, including the chief executive officer, are members of LIB’s board of managers and/or have equity investments in LIB. The Company entered into a MSA dated November 24, 2015 with LIB, a company that engages in research, development, marketing and commercialization of pharmaceutical drugs. Subsequently, the Company and LIB have entered into several task orders for the Company to perform clinical trial related services. The Company recognized total revenue from LIB of $3.7 million during the year ended December 31, 2018 in the Company’s consolidated statement of operations. The Company recognized service revenue from LIB of $1.4 million and $0.2 million during the years ended December 31, 2017 and 2016 in the Company’s consolidated statements of operations, respectively. As of December 31, 2018 and 2017, the Company had, from LIB, Advanced billings of $0.3 million and $0.2 million in the consolidated balance sheets, respectively. In addition, the Company had Accounts receivable and unbilled, net from LIB of $1.0 million and $0.5 million in the consolidated balance sheets at December 31, 2018 and 2017, respectively. CinRX Pharma and subsidiaries (“CinRx”) Certain executives and employees of the Company, including the chief executive officer, are members of CinRx’s board of managers and/or have equity investments in CinRx, a biotech company. The Company and CinRx have entered into several task orders for the Company to perform clinical trial related services. During the year ended December 31, 2018, the Company recognized total revenue from CinRx of $0.5 million in the Company’s consolidated statements of operations. During the year ended December 31, 2017, the Company recognized service revenue from CinRx of $0.4 million in the Company’s consolidated statements of operations. As of December 31, 2018 the Company had Accounts receivable and unbilled, net from CinRx of $0.4 million in the consolidated balance sheets. The Summit, a Dolce Hotel (“The Summit”) The Summit Hotel, located on the Medpace campus, is owned by the chief executive officer, and managed by an unrelated hospitality management entity. Medpace incurs travel lodging and meeting expenses at The Summit. During the year ended December 31, 2018, Medpace incurred expenses of $0.4 million at The Summit. Medpace Investors, LLC Medpace Investors is a noncontrolling shareholder and related party of Medpace Holdings, Inc. Medpace Investors is owned and managed by employees of the Company. The Company’s chief executive officer is also the manager and majority unit holder of Medpace Investors. The Company acts as a paying agent for Medpace Investors with taxing authorities principally in instances when employee tax payments or remittance of withholdings related to equity compensation are required. During the year ended December 31, 2016, the Company paid $0.8 million to various taxing authorities on behalf of Medpace Investors. During the year ended December 31, 2016, the Company received $0.3 million from Medpace Investors for receivables owed to the Company from Symplmed. Additionally, during the year ended December 31, 2016, the Company paid approximately $0.3 million to Medpace Investors due to the settlement of certain liabilities related to the Merger Agreement between the sellers (led by CCMP) and the buyers (led by Cinven). Purchase of Real Estate Properties In December 2016, the Company entered into a purchase agreement for four parcels of real estate property that are closely situated to the Medpace campus in Cincinnati, Ohio, from AT Redevelopment Company, LLC, which is wholly-owned by the Company’s chief executive officer. The purchase price of the real estate property was $0.4 million as determined by an independent third party broker's opinion of value. The transaction closed on January 11, 2017. Leased Real Estate Headquarters Lease The Company has entered into operating leases for its corporate headquarters and a storage space facility with an entity that is wholly owned by the Company’s chief executive officer. The Company has evaluated its relationship with the related party and concluded that the related party is not a variable interest entity because the Company has no direct ownership interest or relationship other than the leases. The lease for headquarters is for an initial term of twelve years through November 2022 with a renewal option for one 10-year term at prevailing market rates. The lease for storage space was through June 2016 and was leased on a month to month basis, thereafter. The Company pays rent, taxes, insurance, and maintenance expenses that arise from the use of the properties. Annual base rent for the corporate headquarters is $2.2 million and allows for adjustments to the rental rate annually for increases in the consumer price index. Lease expense recognized for the years ended December 31, 2018, 2017 and 2016 was $2.2 million, $2.1 million and $2.1 million, respectively. The lease expense was allocated between Direct service costs, excluding depreciation and amortization, and Selling, general and administrative in the consolidated statements of operations. In 2018, Medpace, Inc. entered into a multi-year lease agreement governing future occupancy of additional office space in Cincinnati, Ohio. The lease expires in 2040 and the Company has two 10-year options to extend the term of the lease. Deemed Assets and Deemed Landlord Liabilities The Company entered into two multi-year lease agreements governing the occupancy of space of two buildings in Cincinnati, Ohio with an entity that is wholly owned by the Company’s chief executive officer and certain members of his immediate family. In accordance with the accounting guidance related to leases, the Company was deemed in substance to be the owner of the property during the construction phase and at completion. Accordingly, the Company reflected the buildings and related liabilities as deemed assets from landlord building construction in Property and equipment, net, Other current liabilities, and Deemed landlord liabilities, respectively, on the consolidated balance sheets. The Company assumed occupancy in 2012 and the leases expire in 2027 with the Company having one 10-year option to extend the lease term. The deemed assets are being fully depreciated, on a straight line basis, over the 15-year term of the lease. Deemed landlord liabilities are recorded at their net present value when the Company enters into qualifying leases and are reduced as the Company makes periodic lease payments on the properties. Accretion expense is being recorded over the term of the lease as a component of Interest expense, net in the Company’s consolidated statements of operations. The Company paid $3.8 million, $3.8 million and $3.7 million during the years ended December 31, 2018, 2017 and 2016, respectively. The current and long-term portions of the Deemed landlord liability at December 31, 2018 were $2.1 million and $24.5 million, respectively. The current and long-term portions of the Deemed landlord liability at December 31, 2017 were $1.9 million and $26.6 million, respectively. The Company has recognized $14.6 million and $16.3 million, respectively, of deemed assets, net at December 31, 2018 and 2017 in the consolidated balance sheets. Travel Services Reynolds Jet Management (“Reynolds”) The Company incurs expenses for travel services for company executives provided by a private aviation charter company that is owned by the chief executive officer and the senior vice president of operations of the Company (“private aviation charter”). The Company may contract directly with the private aviation charter for the use of its aircraft or indirectly through a third party aircraft management and jet charter company (the “Aircraft Management Company”). The travel services provided are primarily for business purposes, with certain personal travel paid for as part of the executives’ compensation arrangements. The Aircraft Management Company also makes the private aviation charter aircraft available to third parties. The Company incurred travel expenses of $1.3 million, $1.1 million and $1.0 million during the years ended December 31, 2018, 2017 and 2016, respectively. These travel expenses are recorded in Selling, general and administrative in the Company’s consolidated statements of operations. As of December 31, 2018 and 2017, the Company had Accounts payable due to Reynolds of $0.2 million in the consolidated balance sheets, respectively.

Related Party Transactions

12 Months Ended

Dec. 31, 2018

14. RELATED PARTY TRANSACTIONS

Employee Loans

The Company periodically extends short term loans or advances to employees, typically upon commencement of employment. Total receivables as a result of these employee advances of $0.2 million existed at December 31, 2018

and 2017, respectively, and are included in the Prepaid expenses and other current assets and Other assets line items of the consolidated balance sheets, respectively, depending on the contractual repayment date.

Management Fees

In conjunction with the IPO, the Advisory Services Agreement with Cinven Capital Management (V) General Partner Limited (“Cinven”) expired. Subsequent to the IPO, the Company paid fees for director services provided by Cinven employees that were members of the Company’s Board of Directors and any related committees. The director fees were paid directly to Cinven in accordance with the Company’s non-employee director compensation policy. During the third quarter of 2018, Cinven sold its remaining shares of the Company’s common stock and all three members of the Company’s Board affiliated with Cinven subsequently resigned. During the year ended December 31, 2016, the Company incurred management fees to Cinven of $0.2 million. During the years ended December 31, 2018 and 2017, the Company incurred director fees of $0.1 million, respectively. In connection with these fees, Cinven incurred related travel expenses of less than $0.1 million, $0.1 million and $0.1 million, respectively, during the years ended December 31, 2018, 2017 and 2016.

Service Agreements

Coherus BioSciences, Inc. (“Coherus”) and MX II Associates, LLC (“MXII”)

The chief executive officer of the Company was a member of Coherus BioSciences, Inc.’s (“Coherus”) board of directors until his resignation in the first quarter of 2018. Coherus is no longer considered a related party as of the first quarter of 2018. During 2011 a related party of the Company in which the Company’s chief executive officer is the managing member, MXII, made an investment in Coherus. In early 2012 the Company made a $2.5 million investment in Coherus. Concurrent with the initial investment, MXII secured the exclusive rights for Medpace to perform Phase I through Phase III clinical trial work for certain Coherus’ “bio-similar” drug compounds executed through a MSA. The agreement provides for a minimum fee commitment for clinical trial services and is cancelable without cause by either party upon 30 days prior notice. During the years ended December 31, 2017 and 2016, the Company recognized service revenue of $8.0 million and $22.3 million from Coherus in the Company’s consolidated statements of operations, respectively. In addition, the company recognized Reimbursed out-of-pocket revenue and Reimbursed out-of-pocket expenses with Coherus in the consolidated statements of operations of $1.3 million and $5.1 million during the years ended December 31, 2017 and 2016, respectively. As of December 31, 2017, the Company had Accounts receivable and unbilled, net from Coherus of $0.3 million recorded in the consolidated balance sheets. In addition, the Company had Advanced billings of $1.5 million and Pre-funded study costs of $1.0 million with Coherus recorded in the consolidated balance sheets at December 31, 2017.

Xenon Pharmaceuticals, Inc. (“Xenon”)

Certain executives and employees of the Company, including the chief executive officer, have held equity investments in Xenon, a clinical-stage biopharmaceutical company. In addition, a Medpace employee was a director of Xenon until May 2015. During the second quarter of 2017, the chief executive officer sold his entire equity position held in Xenon. Xenon is no longer considered to be a related party subsequent to this sale. During July 2015 the Company and Xenon entered into an amended MSA agreement for the Company to provide clinical trial related services. The Company recognized service revenue from Xenon of $0.6 million and $1.3 million during the six months ended June 30, 2017 and the year ended December 31, 2016, respectively, in the Company’s consolidated statements of operations. In addition, the Company recognized Reimbursed out-of-pocket revenue and Reimbursed out-of-pocket expenses with Xenon in the consolidated statements of operations of $0.1 million and $0.2 million during the six months ended June 30, 2017 and the year ended December 31, 2016, respectively.

Cymabay Therapeutics, Inc. (“Cymabay”)

Cymabay is a clinical-stage biopharmaceutical company developing therapies to treat metabolic diseases with high unmet medical need, including serious rare and orphan disorders. During the first quarter of 2016, it was announced that a Medpace employee would join Cymabay’s board of directors. The Company and Cymabay entered into a MSA dated October 21, 2016. Subsequently, the Company and Cymabay have entered into several task orders for the Company to perform clinical trial related services. The Company recognized total revenue from Cymabay of $10.8 million during the year ended December 31, 2018 in the Company’s consolidated statements of operations. The Company recognized service revenue from Cymabay of $0.6 million and $0.3 million during the years ended December 31, 2017 and 2016, respectively, in the Company’s consolidated statements of operations. As of

December 31, 2018 and 2017, the Company had Accounts receivable and unbilled, net from Cymabay of $2.5 million and $0.1 million recorded in the consolidated balance sheets, respectively.

LIB Therapeutics LLC and subsidiaries (“LIB”)

Certain executives and employees of the Company, including the chief executive officer, are members of LIB’s board of managers and/or have equity investments in LIB. The Company entered into a MSA dated November 24, 2015 with LIB, a company that engages in research, development, marketing and commercialization of pharmaceutical drugs. Subsequently, the Company and LIB have entered into several task orders for the Company to perform clinical trial related services. The Company recognized total revenue from LIB of $3.7 million during the year ended December 31, 2018 in the Company’s consolidated statement of operations. The Company recognized service revenue from LIB of $1.4 million and $0.2 million during the years ended December 31, 2017 and 2016 in the Company’s consolidated statements of operations, respectively. As of December 31, 2018 and 2017, the Company had, from LIB, Advanced billings of $0.3 million and $0.2 million in the consolidated balance sheets, respectively. In addition, the Company had Accounts receivable and unbilled, net from LIB of $1.0 million and $0.5 million in the consolidated balance sheets at December 31, 2018 and 2017, respectively.

CinRX Pharma and subsidiaries (“CinRx”)

Certain executives and employees of the Company, including the chief executive officer, are members of CinRx’s board of managers and/or have equity investments in CinRx, a biotech company. The Company and CinRx have entered into several task orders for the Company to perform clinical trial related services. During the year ended December 31, 2018, the Company recognized total revenue from CinRx of $0.5 million in the Company’s consolidated statements of operations. During the year ended December 31, 2017, the Company recognized service revenue from CinRx of $0.4 million in the Company’s consolidated statements of operations. As of December 31, 2018 the Company had Accounts receivable and unbilled, net from CinRx of $0.4 million in the consolidated balance sheets.

The Summit, a Dolce Hotel (“The Summit”)

The Summit Hotel, located on the Medpace campus, is owned by the chief executive officer, and managed by an unrelated hospitality management entity. Medpace incurs travel lodging and meeting expenses at The Summit. During the year ended December 31, 2018, Medpace incurred expenses of $0.4 million at The Summit.

Medpace Investors, LLC

Medpace Investors is a noncontrolling shareholder and related party of Medpace Holdings, Inc. Medpace Investors is owned and managed by employees of the Company. The Company’s chief executive officer is also the manager and majority unit holder of Medpace Investors. The Company acts as a paying agent for Medpace Investors with taxing authorities principally in instances when employee tax payments or remittance of withholdings related to equity compensation are required. During the year ended December 31, 2016, the Company paid $0.8 million to various taxing authorities on behalf of Medpace Investors. During the year ended December 31, 2016, the Company received $0.3 million from Medpace Investors for receivables owed to the Company from Symplmed. Additionally, during the year ended December 31, 2016, the Company paid approximately $0.3 million to Medpace Investors due to the settlement of certain liabilities related to the Merger Agreement between the sellers (led by CCMP) and the buyers (led by Cinven).

Purchase of Real Estate Properties

In December 2016, the Company entered into a purchase agreement for four parcels of real estate property that are closely situated to the Medpace campus in Cincinnati, Ohio, from AT Redevelopment Company, LLC, which is wholly-owned by the Company’s chief executive officer. The purchase price of the real estate property was $0.4 million as determined by an independent third party broker's opinion of value. The transaction closed on January 11, 2017.

Leased Real Estate

Headquarters Lease

The Company has entered into operating leases for its corporate headquarters and a storage space facility with an entity that is wholly owned by the Company’s chief executive officer. The Company has evaluated its relationship with the related party and concluded that the related party is not a variable interest entity because the Company has no direct ownership interest or relationship other than the leases. The lease for headquarters is for an initial term of twelve years through November 2022 with a renewal option for one 10-year term at prevailing market rates. The lease for storage space was through June 2016 and was leased on a month to month basis, thereafter. The Company pays rent, taxes, insurance, and maintenance expenses that arise from the use of the properties. Annual base rent for the corporate headquarters is $2.2 million and allows for adjustments to the rental rate annually for increases in the consumer price index. Lease expense recognized for the years ended December 31, 2018, 2017 and 2016 was $2.2 million, $2.1 million and $2.1 million, respectively. The lease expense was allocated between Direct service costs, excluding depreciation and amortization, and Selling, general and administrative in the consolidated statements of operations.

In 2018, Medpace, Inc. entered into a multi-year lease agreement governing future occupancy of additional office space in Cincinnati, Ohio. The lease expires in 2040 and the Company has two 10-year options to extend the term of the lease.

Deemed Assets and Deemed Landlord Liabilities

The Company entered into two multi-year lease agreements governing the occupancy of space of two buildings in Cincinnati, Ohio with an entity that is wholly owned by the Company’s chief executive officer and certain members of his immediate family. In accordance with the accounting guidance related to leases, the Company was deemed in substance to be the owner of the property during the construction phase and at completion. Accordingly, the Company reflected the buildings and related liabilities as deemed assets from landlord building construction in Property and equipment, net, Other current liabilities, and Deemed landlord liabilities, respectively, on the consolidated balance sheets. The Company assumed occupancy in 2012 and the leases expire in 2027 with the Company having one 10-year option to extend the lease term. The deemed assets are being fully depreciated, on a straight line basis, over the 15-year term of the lease. Deemed landlord liabilities are recorded at their net present value when the Company enters into qualifying leases and are reduced as the Company makes periodic lease payments on the properties. Accretion expense is being recorded over the term of the lease as a component of Interest expense, net in the Company’s consolidated statements of operations. The Company paid $3.8 million, $3.8 million and $3.7 million during the years ended December 31, 2018, 2017 and 2016, respectively. The current and long-term portions of the Deemed landlord liability at December 31, 2018 were $2.1 million and $24.5 million, respectively. The current and long-term portions of the Deemed landlord liability at December 31, 2017 were $1.9 million and $26.6 million, respectively. The Company has recognized $14.6 million and $16.3 million, respectively, of deemed assets, net at December 31, 2018 and 2017 in the consolidated balance sheets.

Travel Services

Reynolds Jet Management (“Reynolds”)

The Company incurs expenses for travel services for company executives provided by a private aviation charter company that is owned by the chief executive officer and the senior vice president of operations of the Company (“private aviation charter”). The Company may contract directly with the private aviation charter for the use of its aircraft or indirectly through a third party aircraft management and jet charter company (the “Aircraft Management Company”). The travel services provided are primarily for business purposes, with certain personal travel paid for as part of the executives’ compensation arrangements. The Aircraft Management Company also makes the private aviation charter aircraft available to third parties. The Company incurred travel expenses of $1.3 million, $1.1 million and $1.0 million during the years ended December 31, 2018, 2017 and 2016, respectively. These travel expenses are recorded in Selling, general and administrative in the Company’s consolidated statements of operations. As of December 31, 2018 and 2017, the Company had Accounts payable due to Reynolds of $0.2 million in the consolidated balance sheets, respectively.