Equity Financings (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended		6 Months Ended	7 Months Ended	9 Months Ended
	May. 31, 2015	Apr. 30, 2015	May. 31, 2014	Sep. 30, 2015	Jun. 30, 2015	Jun. 30, 2015	Apr. 30, 2015	Sep. 30, 2015
Equity Financings [Line Items]
Aggregate sales proceeds from issue and sell of shares of common stock under sales agreement with Stifel								$ 64,503
Proceeds from public offering of common stock, net of issuance costs								$ 148,439
Commission percentage paid		2.00%	2.00%
Aggregate stock sold pursuant to the sales agreement (in shares)							5,400,000	3,800,000
Aggregate receivable from sale of common stock under sales agreement with Stifel							$ 73,500	$ 55,200
Underwritten public offering
Equity Financings [Line Items]
Aggregate common stock sold (in shares)	8,337,500
Share price	$ 19.00
Proceeds from public offering of common stock, net of issuance costs	$ 148,400
ATM 2015
Equity Financings [Line Items]
Aggregate stock sold pursuant to the sales agreement (in shares)						500,000
Aggregate receivable from sale of common stock under sales agreement with Stifel				$ 0	$ 9,300
Maximum
Equity Financings [Line Items]
Aggregate sales proceeds from issue and sell of shares of common stock under sales agreement with Stifel		$ 75,000	$ 75,000