Preferred Stock - Series B Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Dec. 21, 2016	Aug. 12, 2013	Mar. 09, 2012	Dec. 31, 2016
Series B Convertible Preferred Stock
Number of common shares sold (in shares)	7,130,000
Percentage of cumulative dividend rate				11.50%
Series B voting convertible preferred stock
Series B Convertible Preferred Stock
Period of closing of offering after which shares are convertible				5 years
Conversion price per share (in dollars per share)				$ 3.25
Conversion ratio, the number of shares of common stock received per share of convertible preferred stock				50
Reclassification of Series B preferred stock into shareholders' equity		$ 38.4
Series B-1 non-voting convertible preferred stock
Series B Convertible Preferred Stock
Number of common shares sold (in shares)			12,308
Offering price per share (in dollars per share)			$ 3,250
Period of closing of offering after which shares are convertible		5 years
Accumulated shares but undeclared dividends (in shares)				455,308
Redemption price (in dollars per share)		$ 7,430