Stockholder's Equity (Details Textuals) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2012 shares	Mar. 31, 2011 $ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares
Preferred Stock [Line Items]
Preferred stock redemption charge | $			$ 9,769	$ 0	$ 0
Preferred stock, shares converted			(4,940)	0	0
Series I Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued		14,375,000
Preferred stock balance issued average rate		0.065
Equivalent number of common stock on conversion of preferred shares		0.846
Initial conversion Price | $ / shares		$ 59.1
Liquidation value per preferred share | $ / shares		$ 50
Preferred stock, shares converted			4,940
Series J Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued	11,500,000
Preferred stock balance issued average rate	0.065
Preferred stock redemption charge | $			$ 9,769