Estimated Fair Value of Financial Instruments - Warrant Liability (Details) - USD ($)		3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017
Changes in the estimated fair value for warrant liability
Reclass of warrant liability to capital contributed in excess of par due to exercise				$ (70,149,633)
Change in fair value	$ 14,600,000	$ (9,835,441)	$ 28,336,865	$ 49,774,638	$ 35,567,205
Warrant Liability.
Fair value assumptions for warrants
Risk-free interest rate				1.93%
Expected remaining term				6 months 15 days
Expected volatility				71.43%
Dividend yield				0.00%
Number of Warrants
Warrants outstanding at beginning of year				18,655,804
Reclass of warrant liability to capital contributed in excess of par due to exercise				(12,205,804)
Warrants outstanding at end of period	18,655,804	6,450,000		6,450,000		18,655,804
Warrant Liability. | Level 2
Changes in the estimated fair value for warrant liability
Fair value at beginning of year				$ 90,706,000
Reclass of warrant liability to capital contributed in excess of par due to exercise				(70,150,000)
Change in fair value				49,775,000
Fair value at end of year	$ 90,706,000	$ 70,331,000		$ 70,331,000		$ 90,706,000
Warrant Liability. | February 10, 2017 stock purchase agreement
Fair value assumptions for warrants
Risk-free interest rate						1.14%
Expected remaining term						6 months 4 days
Expected volatility						69.34%
Dividend yield						0.00%
Warrant Liability. | October 11, 2016 public offering
Fair value assumptions for warrants
Risk-free interest rate						1.38%
Expected remaining term						1 year 3 months 11 days
Expected volatility						73.85%
Dividend yield						0.00%