Preferred Stock - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jan. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		5,000,000
Accrued dividends on Series A-2 Preferred Stock		$ 86,000		$ 71,000
Proceeds from issuance of preferred stock gross		$ 0	$ 1,527,000
Common Stock
Class of Stock [Line Items]
Stock issued for conversion of convertible preferred stock, shares (in shares)		43,000	185,000
Perpetual Series B-1 Preferred Stock
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		100
Preferred stock, shares issued (in shares)		0
Preferred stock, shares outstanding (in shares)		0
Series A-2 Preferred Stock
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		7,500		7,500
Preferred stock, shares issued (in shares)		32		32
Preferred stock, cumulative dividend percentage rate, per annum		5.00%
Preferred stock, stated value		$ 7,500		$ 7,500
Stock issued during period, conversion of convertible securities, price (in dollars per share)		$ 21.60
Preferred stock, shares outstanding (in shares)		32		32
Convertible preferred stock, shares issued upon conversion (in shares)		347
Redemption price per share (in dollars per share)		$ 8,250
Redemption price per share, multiplier (in dollars per share)		$ 7,500
Redemption price per share, multiplier, percentage		110.00%
Stated value (in dollars per share)		$ 0.0001		$ 0.0001
Derivative liability		$ 0
Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		2,800		2,800
Preferred stock, shares issued (in shares)		0		75
Preferred stock, cumulative dividend percentage rate, per annum		0.00%
Preferred stock, stated value		$ 1,000		$ 1,000
Stock issued during period, conversion of convertible securities, price (in dollars per share)		$ 2.80
Preferred stock, shares outstanding (in shares)		0		75
Stated value (in dollars per share)		$ 0.0001		$ 0.0001
Series B Preferred Stock | Preferred Stock
Class of Stock [Line Items]
Stock issued for conversion of convertible preferred stock, shares (in shares)		75	75
Series B Preferred Stock | Common Stock
Class of Stock [Line Items]
Stock issued for conversion of convertible preferred stock, shares (in shares)		26,786
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		1,750		1,750
Preferred stock, shares issued (in shares)		475		525
Preferred stock, stated value		$ 1,000		$ 1,000
Stock issued during period, conversion of convertible securities, price (in dollars per share)	$ 3.00
Preferred stock, shares outstanding (in shares)		475		525
Proceeds from issuance of preferred stock gross	$ 1,750,000
Stated value (in dollars per share)	$ 1,000	$ 0.0001		$ 0.0001
Participation rights, future offerings, max percentage	100.00%
Series C Preferred Stock | Preferred Stock
Class of Stock [Line Items]
Stock issued for conversion of convertible preferred stock, shares (in shares)		50	475
Issuance of stock (in shares)	1,750		1,750
Series C Preferred Stock | Common Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion (in shares)		158,333
Stock issued for conversion of convertible preferred stock, shares (in shares)		16,667
Series D Preferred Stock
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		4,000
Preferred stock, shares issued (in shares)		0
Preferred stock, shares outstanding (in shares)		0
Perpetual Series B Preferred Stock
Class of Stock [Line Items]
Preferred stock, convertible, shares authorized (in shares)		100
Preferred stock, shares issued (in shares)		0
Preferred stock, shares outstanding (in shares)		0