Equity Incentive Plans (Summary of Stock Option Activity) (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Equity Incentive Plans [Abstract]
Shares, Balance at December 31, 2018	136,463
Assumed in the Merger (in shares)	52,602
Shares, Granted	1,157,825
Shares, Forfeited	(374)
Shares, Balance at June 30, 2019	1,346,516	136,463
Shares, Vested or expected to vest at June 30, 2019	1,346,516
Shares, Exercisable at June 30, 2019	179,202
Weighted Average Exercise Price, Outstanding at December 31, 2018	$ 36.31
Assumed in the Merger (in dollars per share)	56.60
Weighted Average Exercise Price, Granted	3.15
Weighted Average Exercise Price, Forfeited	147.35
Weighted Average Exercise Price, Outstanding at June 30, 2019	8.56	$ 36.31
Weighted Average Exercise Price, Vested or expected to vest at June 30, 2019	8.56
Weighted Average Exercise Price, Exercisable at June 30, 2019	$ 41.92
Average Remaining Contractual Term (Years), Outstanding	9 years 1 month 10 days	5 years 7 days
Average Remaining Contractual Term (Years), Vested or expected to vest at June 30, 2019	9 years 1 month 10 days
Average Remaining Contractual Term (Years), Exercisable at June 30, 2019	4 years 1 month 2 days
Intrinsic Value, granted	$ 996,000
Intrinsic Value, Outstanding at June 30, 2019	996,000
Intrinsic Value, Vested or expected to vest at June 30, 2019	$ 996,000