Equity Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Apr. 04, 2017
Class of Stock [Line Items]
Common stock, par value	$ 0.2	$ 0.2
Common stock, shares issued	52,880,134	51,494,318
Proceeds from Issuance of Common Stock	$ 18,623	$ 0	$ 0
At-the-Market Common Stock Program [Member]
Class of Stock [Line Items]
Common stock, par value					$ 0.20
Aggregate Offering Price					$ 100,000
Commission of the gross sales price by share paid percentage					2.00%
Common stock, shares issued	787,547			787,547