v3.8.0.1
Document and Entity Information
9 Months Ended
Sep. 30, 2017
Document Information [Line Items]  
Document Type 6-K
Amendment Flag false
Document Period End Date Sep. 30, 2017
Document Fiscal Year Focus 2017
Document Fiscal Period Focus Q3
Trading Symbol ICLR
Entity Registrant Name ICON PLC
Entity Central Index Key 0001060955
Current Fiscal Year End Date --12-31