Fair Value Measurements - Fair Value of Assets and Liabilities (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Liabilities:
Derivative financial instruments—warrants	$ 18,287	$ 32,315
Estimate of Fair Value Measurement | Recurring basis
Assets:
Money market fund	10,742,715	11,392,093
Total Assets	10,742,715	11,392,093
Liabilities:
Derivative financial instruments—warrants	18,287	32,315
Total Liabilities	18,287	32,315
Estimate of Fair Value Measurement | Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)
Assets:
Money market fund	10,742,715	11,392,093
Total Assets	10,742,715	11,392,093
Liabilities:
Derivative financial instruments—warrants	0	0
Total Liabilities	0	0
Estimate of Fair Value Measurement | Recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Money market fund	0	0
Total Assets	0	0
Liabilities:
Derivative financial instruments—warrants	0	0
Total Liabilities	0	0
Estimate of Fair Value Measurement | Recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Money market fund	0	0
Total Assets	0	0
Liabilities:
Derivative financial instruments—warrants	18,287	32,315
Total Liabilities	$ 18,287	$ 32,315