Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Series D Preferred Stock, outstanding (in shares)	55,000	55,000
Dividends paid for Series D Preferred Stock	$ 399	$ 399
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Series D Preferred Stock, outstanding (in shares)	55,000	55,000
Preferred stock, par value (in dollars per share)	$ 100	$ 100
Accrued annual dividends rate (in dollars per share)	$ 7.25	$ 7.25
Number of preferred stock shares convertible to common shares (in shares)	1,378,000
Maximum number of common stock issuable from conversion of preference shares, without obtaining prior shareholder approval (in shares)	2,703,000
Dividends accrued but unpaid	$ 18	$ 18
Dividends paid for Series D Preferred Stock	$ 399	$ 399