Stockholders' Equity At-the-Market Offering (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Number of shares authorized to be sold under equity distribution agreement (in shares)	8,000,000				8,000,000
Number of common shares issued under equity distribution agreement and outstanding as of period-end (in shares)	3,242,364				3,242,364
Accumulated proceeds from issuance of common shares under equity distribution agreement	$ 61,200				$ 61,200
Common stock issued during period (in shares)					0	10,954,924
Issuance of common stock, net of offering costs	0	$ 0	$ 50,177	$ 157,228
Management fee reimbursements for stock sold	$ 0				$ 0	$ 100
At the Market Offering
Class of Stock [Line Items]
Common stock issued during period (in shares)	0				0	3,077,424
Issuance of common stock, net of offering costs	$ 0				$ 0	$ 58,100