Common Stock (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 20, 2017
Class of Stock [Line Items]
Proceeds from common stock issued			$ 260,000
ATM Program [Member]
Class of Stock [Line Items]
Shares issued, price per share			$ 10.40
Issuance of common stock, shares	0	0	28,474
Proceeds from common stock issued			$ 296,000
Net proceeds from common stock issue			$ 260,000
ATM Program [Member] | Maximum [Member]
Class of Stock [Line Items]
Equity distribution agreement, aggregate price of shares available for sale				$ 50,000,000
ATM Program [Member] | Minimum [Member]
Class of Stock [Line Items]
Public float required to sell shares of common stock				$ 75,000,000
ATM Program, Since Inception [Member]
Class of Stock [Line Items]
Shares issued, price per share	$ 10.18
Issuance of common stock, shares	197,478
Proceeds from common stock issued	$ 2,011,000
Net proceeds from common stock issue	$ 1,879,000
Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock, shares			28,000