Initial and Follow On Public Offerings Initial and Follow On Public Offerings (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended			0 Months Ended	1 Months Ended	0 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Sep. 30, 2013	Sep. 30, 2012	Jun. 12, 2013	Dec. 31, 2012	Sep. 20, 2013	Jun. 11, 2013
Class of Stock [Line Items]
Convertible Preferred Stock, Conversion Ratio					2.84
Common stock, shares outstanding	24,785,000	25,588,000
Offering price per share					15.00
Aggregate offering price, net of issuance costs	$ 0	$ 0	$ 138,613	$ 0
Convertible Debentures [Member] | Interest Expense [Member]
Class of Stock [Line Items]
Recognition of unamortized debt discount upon conversion			2,250	0
Common Stock [Member] | Convertible Debentures [Member]
Class of Stock [Line Items]
Shares isued in debt converstion					443,000	826,000
IPO [Member]
Class of Stock [Line Items]
Common stock, shares outstanding								9,935,000
Aggregate offering proceeds			77,709
Shares of stock issued					750,000
IPO [Member] | Convertible Debentures [Member] | Interest Expense [Member]
Class of Stock [Line Items]
Recognition of unamortized debt discount upon conversion	1				1
IPO [Member] | Convertible Debentures [Member]
Class of Stock [Line Items]
Other income related to conversion option					0
IPO [Member] | Redeemable Preferred Stock, Series A-1 [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Conversion Ratio					0.3521126761
IPO [Member] | Common Stock [Member]
Class of Stock [Line Items]
Aggregate offering price, net of issuance costs					80,213
Underwriting discounts and commissions					6,037
Other offering costs					2,504
Shares of stock issued					5,750,000
IPO [Member] | Common Stock [Member] | Convertible Debentures [Member]
Class of Stock [Line Items]
Shares isued in debt converstion					443,000
IPO [Member] | Convertible A-1 and A-2 Preferred Stock [Member]
Class of Stock [Line Items]
Shares converted into stock					5,336,000
Preferred Stock Dividends, Shares					412,000
Shares isued in debt converstion					443,000
IPO [Member] | Preferred Class A [Member] | Submittal Exchange [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Conversion Ratio					0.50
Shares converted into stock					1,000
Follow On Public Offering [Member]
Class of Stock [Line Items]
Offering price per share							$ 38.00
Aggregate offering price, net of issuance costs							61,221
Aggregate offering proceeds			59,779
Follow On Public Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Underwriting discounts and commissions							2,885
Aggregate offering proceeds							59,779
Other offering costs							1,442
Shares of stock issued							1,687,000
Parent [Member] | IPO [Member]
Class of Stock [Line Items]
Aggregate offering proceeds			77,709		77,709
Parent [Member] | Follow On Public Offering [Member]
Class of Stock [Line Items]
Aggregate offering proceeds			$ 59,779