Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Aug. 05, 2019
Document And Entity Information [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Trading Symbol BNFT  
Entity Registrant Name Benefitfocus,Inc.  
Entity Central Index Key 0001576169  
Entity Current Reporting Status Yes  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Shell Company false  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   32,696,997
Entity File Number 001-36061  
Entity Tax Identification Number 462346314  
Entity Address, Address Line One 100 Benefitfocus Way  
Entity Address, City or Town Charleston  
Entity Address, State or Province South Carolina  
Entity Address, Country US  
Entity Address, Postal Zip Code 29492  
City Area Code 843  
Local Phone Number 849-7476