Subsequent Events (Details) - Common Stock [Member] - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended				6 Months Ended
	Jul. 03, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019
Stock Transactions [Abstract]
Number of shares of common stock sold (in shares)		467,928	560,338	1,320,921	1,751,689
ATM Agreement [Member]
Stock Transactions [Abstract]
Number of shares of common stock sold (in shares)		467,928				1,028,266
Average sales price per common share (in dollars per share)		$ 6.28				$ 5.71
Aggregate proceeds from sales of common stock		$ 2,937				$ 5,873
Sales commissions, fees and other costs associated with issuance of common stock		$ 88				$ 176
Subsequent Event [Member] | ATM Agreement [Member]
Stock Transactions [Abstract]
Number of shares of common stock sold (in shares)	191,342
Average sales price per common share (in dollars per share)	$ 6.21
Aggregate proceeds from sales of common stock	$ 1,188
Sales commissions, fees and other costs associated with issuance of common stock	$ 36