v3.19.2
Cover Page - shares
6 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Cover page.    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Entity Registrant Name SYNEOS HEALTH, INC.  
Entity Central Index Key 0001610950  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Current Fiscal Year End Date --12-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   103,485,261
Entity Shell Company false  
Entity Small Business false  
Entity Emerging Growth Company false  
Title of 12(b) Security Class A Common Stock, $0.01 par value per share  
Trading Symbol SYNH  
Security Exchange Name NASDAQ  
Entity File Number 001-36730  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 27-3403111  
Entity Address, Address Line One 1030 Sync Street  
Entity Address, City or Town Morrisville  
Entity Address, State or Province NC  
Entity Address, Postal Zip Code 27560-5468  
City Area Code 919  
Local Phone Number 876-9300  
Document Quarterly Report true  
Document Transition Report false