Preferred Stock (Series E Redeemable Convertible Preferred Stock) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	6 Months Ended		12 Months Ended
	Feb. 28, 2017	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Mar. 01, 2017
Class of Stock [Line Items]
Issuance costs				$ 1,130
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding	925,000		925,000		925,000
Preferred stock, annual dividend rate	6.25%		6.25%		6.25%
Preferred stock, face value	$ 10.00
Preferred stock, dividend rate increase resulting from failure to pay dividend, with equity offerings	9.50%
Redeemable preferred stock, liquidation preference per share	$ 10.00
Preferred stock, percentage of conversion price at which preferred stock automatically converts to common stock	120.00%
Preferred stock, trading days for preferred stock automatically converting to common stock	60 days
Number of shares redeemable by company when market price is within defined range	490,250
Preferred stock, percentage of liquidation value at which holders can sell	130.00%
Threshold of originally issued preferred stock shares outstanding required for approval of certain transactions by preferred shareholders	434,750
Threshold of originally issued preferred stock shares outstanding required for approval of certain transactions by preferred shareholders, percent	47.00%
Percentage of approval required for certain transactions by preferred shareholders	75.00%
Threshold of amount of related party transactions for aprroval by preferred shareholders	$ 120
Threshold of maximum percentage of shares grantable before shareholder approval required	9.90%
Preferred stock, value	$ 9,900		$ 10,050		$ 10,050
Issuance costs		$ 127		$ 1,130
Series E Preferred Stock [Member] | On Or After February 28,2019 [Member]
Class of Stock [Line Items]
Conversion price per share	$ 13.845
Minimum [Member] | Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, percentage of liquidation value at which company can redeem preferred stock	110.00%
Maximum [Member] | Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, percentage of liquidation value at which company can redeem preferred stock	130.00%
Level 3 [Member] | Redemption Rights [Member] | Series E Preferred Stock [Member]
Class of Stock [Line Items]
Assets fair value	$ 150					$ 150