Significant Accounting Policies - Capital Raising (Details)	3 Months Ended
	Mar. 31, 2017 USD ($) shares
Initial Public Offering [Member]
Offering Period	February 20, 2013
Proceeds From Share Issuance	$ 35,400,000
Shares Issued In Capital Raising Program | shares	2,400,000
July 2016 At The Market Program [Member]
Offering Period	July 29, 2016
Proceeds From Share Issuance	$ 108,200,000
Stock To Be Issued Value Original	$ 125,000,000
Shares Issued In Capital Raising Program | shares	10,174,992
February 2017 At The Market Program [Member]
Offering Period	February 23, 2017
Proceeds From Share Issuance	$ 12,800,000
Stock To Be Issued Value Original	$ 125,000,000
Shares Issued In Capital Raising Program | shares	1,286,196
Shares Issued After Quarter End | shares	594,784
Proceeds After Quarter End	$ 6,000,000