XML 35 R1.htm IDEA: XBRL DOCUMENT v3.20.1
Document And Entity Information - shares
 3 Months Ended
Mar. 31, 2020
May 06, 2020
Document And Entity Information    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Mar. 31, 2020  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q1  
Entity Registrant Name United States Natural Gas Fund, LP  
Entity Central Index Key 0001376227  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Trading Symbol UNG  
Entity Common Stock, Shares Outstanding   32,984,588
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Shell Company false