Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 03, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	May 08, 2019	Dec. 31, 2018	May 10, 2017
Class of Stock [Line Items]
Common stock shares authorized		100,000,000		100,000,000			100,000,000
Common stock, par value		$ 0.01		$ 0.01			$ 0.01
Preferred stock shares authorized		50,000,000		50,000,000			50,000,000
Preferred stock, par value		$ 0.01		$ 0.01			$ 0.01
Common stock shares issued		31,249,373		31,249,373			30,154,791
Common stock shares outstanding		31,249,373		31,249,373			30,154,791
Common stock shares issued related to vesting of RSUs				300,000
Net proceeds from issuances of common stock				$ 25,817	$ 31,230
First Amended And Restated 2013 Long-Term Incentive Plan [Member]
Class of Stock [Line Items]
Common stock shares for stock award issuance								1,800,000
2017 Incentive Plan [Member]
Class of Stock [Line Items]
Common stock shares for stock award, available for issuance						1,631,000
Common stock shares rolled into plan								600,000
Distribution Agreement [Member]
Class of Stock [Line Items]
Aggregate offering price	$ 100,000
Available for sale		$ 56,100		$ 56,100
Common stock shares sold and issued		800,000	600,000	900,000	1,100,000
Net proceeds from issuances of common stock		$ 23,700	$ 17,400	$ 26,500	$ 32,400
Comissions and fees paid to Sales Agents		$ 600	$ 500	$ 700	$ 1,100