Related Party Transactions - Additional Information (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) Building RenewalOption Agreement	Dec. 31, 2016 USD ($) Parcel	Dec. 31, 2015 USD ($) shares	Dec. 31, 2012 USD ($)
Related Party Transaction [Line Items]
Service revenue with related parties		$ 11,100,000	$ 24,100,000	$ 24,000,000
Reimbursed out-of-pocket revenue with related parties		1,500,000	5,400,000	6,900,000
Reimbursed out-of-pocket expenses with related parties		1,500,000	5,400,000	6,900,000
Accounts receivable and unbilled, net		1,000,000	2,300,000
Advanced billings		1,700,000	7,600,000
Pre-funded study costs with related parties		1,000,000	3,900,000
Deemed landlord liability, long-term portions		26,602,000	28,527,000
Stock-based compensation expense		4,463,000	9,815,000	$ 22,324,000
Employee Stock Purchase Agreement
Related Party Transaction [Line Items]
Number of common stock purchase by employee | shares				37,037
Stock-based compensation expense				$ 0
Cinven
Related Party Transaction [Line Items]
Management fees expense with related party			200,000	300,000
Travel expenses with related party		100,000	100,000	100,000
Accounts payable to related party			100,000
Director fees with related party		100,000	100,000
Cinven | Maximum
Related Party Transaction [Line Items]
Accounts payable to related party		100,000
Medpace Investors
Related Party Transaction [Line Items]
Related party tax expense			800,000	900,000
Repayments of Related Party Debt			300,000
Proceeds from Related Party Debt			300,000
Prepaid Expenses and Other Current Assets | U.S. State and Local
Related Party Transaction [Line Items]
Due from related party			100,000
Prepaid Expenses and Other Current Assets | Maximum | Other Taxing Authorities
Related Party Transaction [Line Items]
Due from related party			100,000
Other Assets | U.S. State and Local
Related Party Transaction [Line Items]
Due from related party			100,000
Other Current Liabilities | Maximum | Other Taxing Authorities
Related Party Transaction [Line Items]
Due to related party			0
Other Current Liabilities | Former Owner Member
Related Party Transaction [Line Items]
Due to related party			100,000
Other Long-term Liabilities | Former Owner Member
Related Party Transaction [Line Items]
Due to related party			100,000
Employee Loans | Prepaid Expenses and Other Current Assets and Other Assets
Related Party Transaction [Line Items]
Employee advances receivables		200,000
Employee Loans | Other Assets
Related Party Transaction [Line Items]
Employee advances receivables			200,000
Service Agreements | Symplmed
Related Party Transaction [Line Items]
Service revenue with related parties		0		1,200,000
Service Agreements | Symplmed | Maximum
Related Party Transaction [Line Items]
Service revenue with related parties		100,000	(100,000)
Service Agreements | Coherus Bio Sciences Inc
Related Party Transaction [Line Items]
Service revenue with related parties		$ 8,000,000	22,300,000	22,100,000
Amount of investment					$ 2,500,000
Service agreement cancellation notice period		30 days
Reimbursed out-of-pocket revenue with related parties		$ 1,300,000	5,100,000	6,900,000
Reimbursed out-of-pocket expenses with related parties		1,300,000	5,100,000	$ 6,900,000
Accounts receivable and unbilled, net		300,000	2,000,000
Advanced billings		1,500,000	6,300,000
Pre-funded study costs with related parties		1,000,000	3,800,000
Service Agreements | MX II Associates LLC
Related Party Transaction [Line Items]
Percentage of sales commission				10.00%
Commission paid				$ 1,100,000
Service Agreements | Xenon
Related Party Transaction [Line Items]
Service revenue with related parties	$ 600,000		1,300,000
Reimbursed out-of-pocket revenue with related parties	100,000		200,000
Reimbursed out-of-pocket expenses with related parties	$ 100,000		200,000
Accounts receivable and unbilled, net			300,000
Advanced billings			1,300,000
Pre-funded study costs with related parties			100,000
Service Agreements | Cymabay
Related Party Transaction [Line Items]
Service revenue with related parties		600,000	300,000	100,000
Accounts receivable and unbilled, net		100,000
Service Agreements | Cymabay | Maximum
Related Party Transaction [Line Items]
Accounts receivable and unbilled, net			100,000
Service Agreements | LIB
Related Party Transaction [Line Items]
Service revenue with related parties		1,400,000	200,000
Accounts receivable and unbilled, net		500,000
Advanced billings		200,000
Service Agreements | LIB | Maximum
Related Party Transaction [Line Items]
Accounts receivable and unbilled, net			100,000
Advanced billings			$ 100,000
Service Agreements | CinRx
Related Party Transaction [Line Items]
Service revenue with related parties		400,000
Purchase of Real Estate Properties | Chief Executive Officer
Related Party Transaction [Line Items]
Number of parcel in real estate property | Parcel			4
Purchase price of real estate property		$ 400,000
Transaction closed date		Jan. 11, 2017
Leased Real Estate | Chief Executive Officer
Related Party Transaction [Line Items]
Term of lease		12 years
Lease expiration period		2022-11
Number of lease renewal, 10-year option | RenewalOption		1
Lease term upon renewal		10 years
Annual base rent		$ 2,100,000
Lease expense recognized		$ 2,100,000	$ 2,100,000	2,100,000
Storage space lease basis		month to month basis
Leased Real Estate | Chief Executive Officer And Immediate Family
Related Party Transaction [Line Items]
Number of lease renewal, 10-year option | RenewalOption		1
Number of lease agreements | Agreement		2
Number of buildings | Building		2
Lease occupancy year		2012
Lease expiration year		2027
Lease term upon renewal		10 years
Term of lease		15 years
Related party capital lease payments		$ 3,800,000	3,700,000	3,400,000
Deemed landlord liability, current		1,900,000	1,700,000
Deemed landlord liability, long-term portions		26,600,000	28,500,000
Leased Real Estate | Property and Equipment, Net | Chief Executive Officer And Immediate Family | Building
Related Party Transaction [Line Items]
Deemed assets, net		16,300,000	18,100,000
Travel Services | Chief Executive Officer
Related Party Transaction [Line Items]
Travel expenses with related party		$ 1,100,000	$ 1,000,000	$ 900,000