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Short-Term Investments (Tables)
6 Months Ended
Sep. 30, 2017
Summary of Investment Holdings [Line Items]  
Schedule of amortized cost and fair value of investment securities held-to-maturity
   Investment Securities Held-to-Maturity  Estimated 
   

Amortized

Cost

  

Unrealized

Gains

  

Unrealized

Losses

  fair value 
 At September 30, 2017            
 Corporate debt securities $1,997,792  $  $  $1,997,792 
 Other debt securities            
   $1,997,792  $  $  $1,997,792 
 At March 31, 2017                
 Corporate debt securities $  $  $  $ 
 Other debt securities            
   $  $  $  $ 
Investment securities [Member]  
Summary of Investment Holdings [Line Items]  
Schedule of amortized cost and fair value of investment securities held-to-maturity
   September 30,
2017
  March 31,
2017
 
 Due in one year or less $1,997,792  $ 
 Due after one year through five years      
 Due after five years through ten years      
 Due after ten years      
 Total $1,997,792  $