Warrants, Restricted Stock, Restricted Stock Units, Options and Option Matching Rights - Warrants (Details) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Aug. 19, 2009	Dec. 31, 2016	Jan. 24, 2018	Dec. 31, 2017	Feb. 17, 2016	Dec. 31, 2015
Class of Warrant or Right [Line Items]
Number of securities declined to exercise (in shares)						204,706
Number of shares that may be purchased by warrants (shares)		83,334		60,000
Exercise price of right (usd per right)		$ 30.00		$ 81.50
Proceeds from warrant exercises		$ 2.5
Class of warrant or right, outstanding (in shares)		133,000
Preferred Stock, Shares Issued				200,000
Option Matching Rights [Member]
Class of Warrant or Right [Line Items]
Class of Warrant or Right, Number of Securities Exercised to Trigger Option Matching Rights	200,000
Class of Warrant or Right, Option Exercise Notice	5 days
Class of Warrant or Right, Option Exercise, Second Notice	10 days
Number of securities declined to exercise (in shares)					204,706
Class of Warrant or Right, Option Cancellation Notice	10 days
Class of warrant or right, outstanding (in shares)				3,000
Subsequent Event | Option Matching Rights [Member]
Class of Warrant or Right [Line Items]
Number of securities declined to exercise (in shares)			1,666
Number of shares that may be purchased by warrants (shares)			1,666
Exercise price of right (usd per right)			$ 14.95