Earnings per Share (Reconciliation Of Number Of Common Shares Used In Calculating Basic And Diluted EPS) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings per Share [Line Items]
Net income (loss)	$ (31,238)	$ 711	$ (31,081)	$ 6,367
Basic weighted-average shares outstanding	40,784,129	40,842,672	40,836,503	40,822,326
Diluted weighted-average shares outstanding	40,784,129	40,963,488	40,836,503	40,932,852
Basic net income (loss) per share	$ (0.77)	$ 0.02	$ (0.76)	$ 0.16
Diluted net income (loss) per share	$ (0.77)	$ 0.02	$ (0.76)	$ 0.16
Performance shares [Member]
Earnings per Share [Line Items]
Incremental shares		100,915		92,130
Restricted stock units [Member]
Earnings per Share [Line Items]
Incremental shares		19,901		18,396