Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		13 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	May 02, 2018	Dec. 31, 2017	Apr. 04, 2017
Class of Stock [Line Items]
Common stock, par value	$ 0.20			$ 0.20
Common stock, shares issued	54,089,366			52,880,134
Proceeds from issuance of common stock, net of issuance costs	$ 0	$ 18,623
Terminated May 2, 2018 [Member] | At-the-Market Common Stock Program [Member]
Class of Stock [Line Items]
Common stock, par value					$ 0.20
Aggregate Offering Price					$ 100,000
Proceeds from issuance of common stock, net of issuance costs			$ 18,623
Commission of the gross sales price by share paid percentage					2.00%
ATM Distribution Agreement [Member] | Terminated May 2, 2018 [Member] | At-the-Market Common Stock Program [Member]
Class of Stock [Line Items]
Common stock, shares issued			787,547