Stock-Based Compensation - Service Based Stock Options (Details) - USD ($)	6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Weighted Average Exercise Price
Exercised (in dollars per share)	$ 2.06		$ 2.92
Stock option awards - Service based awards
Shares Underlying Options
Outstanding at the beginning of the period (in shares)	8,210,024	7,856,480	7,856,480
Granted (in shares)	1,610,344	523,105
Exercised (in shares)		(30,000)
Forfeited (in shares)	(211,471)	(550,549)
Expirations (in shares)	(3,983,335)
Outstanding at the end of the period (in shares)	5,625,562	7,799,036	8,210,024	7,856,480
Exercisable at end of period (in shares)	2,809,954	6,183,193
Weighted Average Exercise Price
Outstanding at the beginning of the period (in dollars per share)	$ 7.06	$ 7.50	$ 7.50
Granted (in dollars per share)	2.24	4.33
Exercised (in dollars per share)		4.93
Forfeited (in dollars per share)	4.41	6.67
Expirations (in dollar per share)	8.30
Outstanding at the end of the period (in dollars per share)	4.90	7.36	$ 7.06	$ 7.50
Exercisable (in dollars per share)	$ 7.09	$ 8.16
Weighted Average Remaining Contractual Term
Outstanding, Weighted Average Remaining Contractual Term	6 years 8 months 12 days	5 years 4 months 24 days	5 years 1 month 6 days	5 years 2 months 12 days
Granted, Weighted Average Remaining Contractual Term	5 years 10 months 24 days	9 years 8 months 12 days
Exercisable, Weighted Average Remaining Contractual Term	4 years 3 months 18 days	4 years 3 months 18 days
Aggregate Intrinsic Value
Outstanding	$ 1,100	$ 2,500	$ 107,150	$ 0
Intrinsic Value	$ 0	$ 0