Preferred Stock (Series D Preferred Stock) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		12 Months Ended
	Feb. 28, 2017	Feb. 27, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 16, 2016
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding						6,245,156	6,245,156
Preferred stock, annual dividend rate				6.25%		6.25%
Preferred stock, face value						$ 10.00
Aggregate outstanding shares required for liquidation election						40.00%
Conversion price per share	$ 10.40					$ 10.40
Debt instrument conversion ratio to common stock						0.9615385
Preferred stock, partial redemption value						$ 30,000
Series D Preferred Stock [Member] | On Or Before March 16, 2019 [Member]
Class of Stock [Line Items]
Preferred stock, redemption price						$ 12.00
Series D Preferred Stock [Member] | March 16, 2019 to March 16, 2020 [Member]
Class of Stock [Line Items]
Preferred stock, redemption price						13.00
Series D Preferred Stock [Member] | On Or After March 16, 2020 [Member]
Class of Stock [Line Items]
Preferred stock, redemption price						14.00
Series D Preferred Stock [Member] | On Or Before September 30,2021 [Member]
Class of Stock [Line Items]
Preferred stock, redemption price						$ 14.00
Series D Preferred Stock [Member] | After September 30, 2021 [Member]
Class of Stock [Line Items]
Preferred stock, annual dividend rate						12.50%
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, shares outstanding					925,000
Preferred stock, annual dividend rate	6.25%		6.25%		6.25%
Preferred stock, face value	$ 10.00
Shares issued upon conversion		925,000
Shares issued upon conversion, amount	$ 9,250
Minimum [Member] | Series D Preferred Stock [Member]
Class of Stock [Line Items]
Debt instrument conversion amount upon closing of qualified offering						$ 50,000
Maximum [Member] | Series D Preferred Stock [Member]
Class of Stock [Line Items]
Debt instrument conversion amount upon closing of qualified offering						$ 75,000
Common Stock [Member]
Class of Stock [Line Items]
Shares issued upon conversion	6,004,957	6,004,957