Selected Quarterly Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Information

Year Ended December 31, 2017	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Revenue	$	1,597		$	1,597		$	1,598		$	1,597
Total operating expenses		15,562			14,611			14,676			15,033
Loss from operations		(13,965	)		(13,014	)		(13,078	)		(13,436	)
Preferred stock dividends		(4,171	)		(4,865	)		(4,903	)		(4,999	)
Net (loss) applicable to common shareholders		(19,658	)		(17,727	)		(17,604	)		(18,272	)
Loss per share, basic and diluted	$	(0.15	)	$	(0.13	)	$	(0.13	)	$	(0.12	)
Year Ended December 31, 2016	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Revenue	$	1,969		$	1,697		$	1,598		$	1,597
Total operating expenses		14,009			132,939			12,512			12,708
Loss from operations		(12,040	)		(131,242	)		(10,914	)		(11,111	)
Preferred stock dividends		—			—			(3,591	)		(3,532	)
Net (loss) applicable to common shareholders		(12,019	)		(131,200	)		(14,445	)		(14,756	)
Loss per share, basic and diluted	$	(0.09	)	$	(1.01	)	$	(0.11	)	$	(0.11	)