Stockholders' Equity - Stock options outstanding and exercisable (Details)
 6 Months Ended
Dec. 31, 2019
$ / shares
shares
Options Outstanding 3,416,580
Options Exercisable 3,097,745
Range One [Member]  
Option Exercise Price | $ / shares $ 0.59
Options Outstanding 8,150
Remaining Contractual Life (in years) 2 years 6 months
Options Exercisable 8,150
Range Two [Member]  
Option Exercise Price | $ / shares $ 0.60
Options Outstanding 5,000
Remaining Contractual Life (in years) 2 years 6 months
Options Exercisable 5,000
Range Three [Member]  
Option Exercise Price | $ / shares $ 0.65
Options Outstanding 6,150
Remaining Contractual Life (in years) 2 years 6 months
Options Exercisable 6,150
Range Four [Member]  
Option Exercise Price | $ / shares $ 0.70
Options Outstanding 225,000
Remaining Contractual Life (in years) 5 years 11 months 5 days
Options Exercisable 225,000
Range Five [Member]  
Option Exercise Price | $ / shares $ 0.77
Options Outstanding 49,500
Remaining Contractual Life (in years) 3 years 6 months 29 days
Options Exercisable 49,500
Range Six [Member]  
Option Exercise Price | $ / shares $ 0.80
Options Outstanding 16,000
Remaining Contractual Life (in years) 5 years 7 months 21 days
Options Exercisable 16,000
Range Seven [Member]  
Option Exercise Price | $ / shares $ 0.90
Options Outstanding 25,667
Remaining Contractual Life (in years) 4 years 3 months 22 days
Options Exercisable 25,667
Range Eight [Member]  
Option Exercise Price | $ / shares $ 0.97
Options Outstanding 6,000
Remaining Contractual Life (in years) 2 years 6 months
Options Exercisable 6,000
Range Nine [Member]  
Option Exercise Price | $ / shares $ 1.00
Options Outstanding 28,249
Remaining Contractual Life (in years) 3 years 11 months 5 days
Options Exercisable 28,249
Range Ten [Member]  
Option Exercise Price | $ / shares $ 1.02
Options Outstanding 187,000
Remaining Contractual Life (in years) 7 months 2 days
Options Exercisable 187,000
Range Eleven [Member]  
Option Exercise Price | $ / shares $ 1.05
Options Outstanding 400,529
Remaining Contractual Life (in years) 6 years 7 months 2 days
Options Exercisable 400,529
Range Twelve [Member]  
Option Exercise Price | $ / shares $ 1.07
Options Outstanding 33,898
Remaining Contractual Life (in years) 2 years 9 months 15 days
Options Exercisable 33,898
Range Thirteen [Member]  
Option Exercise Price | $ / shares $ 1.09
Options Outstanding 129,165
Remaining Contractual Life (in years) 5 years 10 months 10 days
Options Exercisable 129,165
Range Fourteen [Member]  
Option Exercise Price | $ / shares $ 1.10
Options Outstanding 105,000
Remaining Contractual Life (in years) 5 years 6 months
Options Exercisable 105,000
Range Fifteen [Member]  
Option Exercise Price | $ / shares $ 1.14
Options Outstanding 3,674
Remaining Contractual Life (in years) 2 years 6 months
Options Exercisable 3,674
Range Sixteen [Member]  
Option Exercise Price | $ / shares $ 1.15
Options Outstanding 209,400
Remaining Contractual Life (in years) 4 years 7 months 10 days
Options Exercisable 209,400
Range Seventeen [Member]  
Option Exercise Price | $ / shares $ 1.20
Options Outstanding 352,414
Remaining Contractual Life (in years) 7 years 6 months 26 days
Options Exercisable 346,912
Range Eighteen [Member]  
Option Exercise Price | $ / shares $ 1.25
Options Outstanding 32,000
Remaining Contractual Life (in years) 3 years 1 month 13 days
Options Exercisable 32,000
Range Nineteen [Member]  
Option Exercise Price | $ / shares $ 1.30
Options Outstanding 243,000
Remaining Contractual Life (in years) 2 years 2 months 5 days
Options Exercisable 243,000
Range Twenty [Member]  
Option Exercise Price | $ / shares $ 1.50
Options Outstanding 195,000
Remaining Contractual Life (in years) 2 years 10 months 17 days
Options Exercisable 195,000
Range Twenty One [Member]  
Option Exercise Price | $ / shares $ 1.59
Options Outstanding 35,000
Remaining Contractual Life (in years) 8 years 4 months 10 days
Options Exercisable 20,417
Range Twenty Two [Member]  
Option Exercise Price | $ / shares $ 1.75
Options Outstanding 1,067
Remaining Contractual Life (in years) 2 years 6 months
Options Exercisable 1,067
Range Twenty Three [Member]  
Option Exercise Price | $ / shares $ 1.80
Options Outstanding 94,050
Remaining Contractual Life (in years) 3 years 7 months 17 days
Options Exercisable 94,050
Range Twenty Four [Member]  
Option Exercise Price | $ / shares $ 1.85
Options Outstanding 24,000
Remaining Contractual Life (in years) 3 years 1 month 2 days
Options Exercisable 24,000
Range Twenty Five [Member]  
Option Exercise Price | $ / shares $ 1.95
Options Outstanding 275,000
Remaining Contractual Life (in years) 8 years 6 months 4 days
Options Exercisable 143,750
Range Twenty Six [Member]  
Option Exercise Price | $ / shares $ 2.40
Options Outstanding 398,667
Remaining Contractual Life (in years) 8 years 10 months 17 days
Options Exercisable 309,167
Range Twenty Seven [Member]  
Option Exercise Price | $ / shares $ 2.49
Options Outstanding 50,000
Remaining Contractual Life (in years) 9 years 9 months
Range Twenty Eight [Member]  
Option Exercise Price | $ / shares $ 2.50
Options Outstanding 20,000
Remaining Contractual Life (in years) 9 years 4 months 17 days
Options Exercisable 0
Range Twenty Nine [Member]  
Option Exercise Price | $ / shares $ 3.13
Options Outstanding 258,000
Remaining Contractual Life (in years) 9 years 10 months 13 days
Options Exercisable 250,000