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, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings per Share [Line Items]
Net income	$ 711	$ 16,270	$ 6,367	$ 36,620
Basic weighted-average shares outstanding (in shares)	40,842,672	40,740,979	40,822,326	40,726,397
Diluted weighted-average shares outstanding (in shares)	40,963,488	40,850,253	40,932,852	40,833,041
Basic net income per share (in shares)	$ 0.02	$ 0.40	$ 0.16	$ 0.90
Diluted net income per share (in shares)	$ 0.02	$ 0.40	$ 0.16	$ 0.90
Total anti-dilutive shares excluded from the calculation (in shares)	1,000	13,691	80,726	38,776
Performance shares [Member]
Earnings per Share [Line Items]
Incremental shares (in shares)	100,915	82,013	92,130	77,139
Total anti-dilutive shares excluded from the calculation (in shares)	0	13,322	60,547	38,776
Restricted stock units [Member]
Earnings per Share [Line Items]
Incremental shares (in shares)	19,901	24,642	18,396	26,727
Total anti-dilutive shares excluded from the calculation (in shares)	1,000	369	20,179	0
Stock options [Member]
Earnings per Share [Line Items]
Incremental shares (in shares)	0	2,619	0	2,778