Quarterly report pursuant to Section 13 or 15(d)

Document And Entity Information

Document And Entity Information - shares
6 Months Ended
Jun. 30, 2021
Aug. 12, 2021
Document Information [Line Items]    
Entity Central Index Key 0000803578  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2021  
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2021  
Document Transition Report false  
Entity File Number 000-22405  
Entity Incorporation, State or Country Code VA  
Entity Tax Identification Number 54-1167364  
Entity Address, Address Line One 12015 Lee Jackson Memorial Highway  
Entity Address, City or Town Fairfax  
Entity Address, State or Province VA  
Entity Address, Postal Zip Code 22033  
City Area Code 703  
Local Phone Number 383-3000  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   12,045,690