Stockholders' Equity Common Stock Rollforward (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Mar. 06, 2019	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Common stock issued during period (in shares)		0	10,954,924
Proceeds from issuance of common stock, net of offering costs	$ 130,200	$ 0	$ 207,405
Issuance costs incurred in common stock offering	1,600
Increase (Decrease) in Common Stock Outstanding [Roll Forward]
Common shares outstanding at beginning of period (in shares)		54,853,205	43,621,174
Common stock issued during period (in shares)		0	10,954,924
Restricted stock issued during period (in shares)		351,877	277,107
Common shares outstanding at end of period (in shares)		55,205,082	54,853,205
Over-Allotment Option
Class of Stock [Line Items]
Proceeds from issuance of common stock, net of offering costs	$ 19,500
Common Stock
Class of Stock [Line Items]
Common stock issued during period (in shares)	6,850,000
Increase (Decrease) in Common Stock Outstanding [Roll Forward]
Common stock issued during period (in shares)	6,850,000
Common Stock | Over-Allotment Option
Class of Stock [Line Items]
Common stock issued during period (in shares)	1,027,500
Increase (Decrease) in Common Stock Outstanding [Roll Forward]
Common stock issued during period (in shares)	1,027,500