Stockholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended	1 Months Ended	2 Months Ended	1 Months Ended						2 Months Ended	3 Months Ended
	Dec. 31, 2014 Vote	Nov. 30, 2013	Feb. 29, 2012	Jan. 31, 2012	Dec. 31, 2012	Apr. 30, 2014	Jul. 31, 2012	Feb. 29, 2012	Jul. 31, 2014	Apr. 30, 2014	Sep. 30, 2014	Jul. 31, 2014
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Number of votes per share that common stockholders are entitled to receive	1
Public Offering
Stockholders' Equity
Number of shares sold by the entity		16,100,000	8,050,000
Selling price per share (in dollars per share)		$ 3.75	$ 4.40					4.40
Net proceeds after deducting commissions and other transactions costs		$ 57.1	$ 33.0
Value of shares sold by the entity		60.4	35.4
Public Offering | Largest Shareholder Members Of Board Of Directors And Entities Affiliated With Directors
Stockholders' Equity
Number of shares sold by the entity		5,183,333
Selling price per share (in dollars per share)		$ 3.75
Public Offering | Largest Shareholder and Member of Board of Directors
Stockholders' Equity
Number of shares sold by the entity			1,136,363	1,136,363
Selling price per share (in dollars per share)				$ 4.40
Registered Direct Offering
Stockholders' Equity
Number of shares sold by the entity					7,000,000
Selling price per share (in dollars per share)					$ 8.60
Net proceeds after deducting commissions and other transactions costs					59.8
Registered Direct Offering | Largest Shareholder Members Of Board Of Directors And Entities Affiliated With Directors
Stockholders' Equity
Number of shares sold by the entity						1,250,000
Selling price per share (in dollars per share)						$ 4.01				$ 4.01
Net proceeds after deducting commissions and other transactions costs						5.0
Registered Direct Offering | Directors Including Largest Shareholder
Stockholders' Equity
Number of shares sold by the entity					2,649,535		3,976,702
Selling price per share (in dollars per share)					$ 8.60		$ 6.49
Net proceeds after deducting commissions and other transactions costs							25.8
Public Offering-Initial Offering
Stockholders' Equity
Number of shares sold by the entity		14,000,000		7,000,000
Public Offering-Full Exercise
Stockholders' Equity
Number of shares sold by the entity		2,100,000						1,050,000
At-The-Market Issuance Sales Agreement
Stockholders' Equity
Number of shares sold by the entity										6,588,875	5,679,685	9,424,193
Net proceeds after deducting commissions and other transactions costs										27.3	22.5	39.2
Value of shares sold by the entity										28.0	23.0	40.0
Weighted average selling price (in dollars per share)										$ 4.25	$ 4.05	$ 4.24
Maximum aggregate offering price									$ 50.0		$ 27.0
MLV & Co. LLC | At-The-Market Issuance Sales Agreement | Maximum
Stockholders' Equity
Percentage of gross proceeds payable as commission	3.00%