Stockholders' Equity – Equity Distribution Agreement (Details) - USD ($)		1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 13, 2019	Oct. 31, 2017	Aug. 31, 2015	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of shares under equity distribution agreement (in shares)					1,692,289
Net proceeds from issuance of common stock	$ 37,400,000
2017 Equity Distribution Agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of Equity Distribution Agreement		3 years
Value of common stock authorized under EDA		$ 50,000,000
Net proceeds from issuance of common stock					$ 2,100,000
Remaining value of common stock shares available under EDA				$ 34.8	$ 34.8
2017 Equity Distribution Agreement | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock, commission percentage			3.00%
2017 Equity Distribution Agreement | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of shares under equity distribution agreement (in shares)				1,692,289	1,692,289	0
Net proceeds from issuance of common stock				$ 2,100,000