v3.19.3
Cover Page - shares
9 Months Ended
Sep. 30, 2019
Oct. 25, 2019
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Entity Registrant Name MEDNAX, INC.  
Entity Central Index Key 0000893949  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Common Stock, Shares Outstanding   84,298,441
Title of 12(b) Security Common Stock  
Trading Symbol MD  
Security Exchange Name NYSE  
Entity File Number 001-12111  
Entity Incorporation, State or Country Code FL  
Entity Tax Identification Number 26-3667538  
Entity Address, Address Line One 1301 Concord Terrace  
Entity Address, City or Town Sunrise  
Entity Address, State or Province FL  
Entity Address, Postal Zip Code 33323  
City Area Code 954  
Local Phone Number 384-0175  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false