Organization and Significant Accounting Policies - Summary of Anti-dilutive Securities Excluded from Calculation of Weighted Average Common Shares Outstanding (Details) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stock Options | 2008 Stock Plan and 2016 Stock Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	2,010,603	1,544,857
Stock Options | Inducement Options Outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	96,167	100,500
Stock Appreciation Rights (SARs) | 2016 Stock Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	600,000	0
January 2018 Public Offering | Warrants to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	10,000,000	10,000,000
March 2020 Public Offering | Warrants to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	12,078,292	0
March 2020 Registered Direct Offering | Warrants to Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities (in shares)	558,140	0