Stockholders' Equity (Details) - USD ($) $ in Millions	1 Months Ended
	Jul. 31, 2016	Jun. 30, 2016	May 31, 2016	Mar. 31, 2015
Cantor Fitzgerald & Co. Agreement
Stockholders' Equity
Common stock issued (in shares)	1,109,536	593,111
Net proceeds from sale of stock	$ 5.0	$ 2.7
Maximum aggregate offering price of common stock			$ 60.0
Fixed commission rate			3.00%
Aggregate gross offering price available	$ 52.0
Underwritten Public Offering
Stockholders' Equity
Common stock issued (in shares)				8,337,500
Net proceeds from sale of stock				$ 188.8