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Investments in Marketable Securities - Summary of Investments Classified As Available-For-Sale Securities (Parenthetical) (Detail)
Jun. 30, 2017
USD ($)
Security
Dec. 31, 2016
USD ($)
Security
Schedule of Available-for-sale Securities [Line Items]    
Number of securities in unrealized gain position | Security 0  
Number of securities in unrealized loss position | Security 19 25
Unrealized losses, aggregate $ 5,999  
Short-term investments – available for sale 8,689,630 $ 10,075,058
Corporate debt securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Unrealized losses, aggregate 5,999 6,892
Short-term investments – available for sale 8,499,850 10,075,058
Short-term investments classified as available-for-sale, noncurrent 0 0
Certificates of deposit [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Short-term investments – available for sale 189,780  
Short-term investments classified as available-for-sale, noncurrent 0  
Cash equivalents [Member] | Corporate debt securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Short-term investments – available for sale 0 0
Cash equivalents [Member] | Certificates of deposit [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Short-term investments – available for sale 0  
Maximum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Unrealized losses, individually 836 1,000
Unrealized losses, aggregate $ 5,999 $ 7,000