Earnings Per Share (Schedule Computing Earnings Per Share) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Earnings Per Share [Abstract]
Net income/(loss) available to common shareholders	$ (33,745)	$ 8,762	$ 13,296	$ 25,495
Weighted average number of shares used in calculating basic net income per share	31,349	31,263	31,329	31,243
Stock options		144	69	130
Long-term incentive plan		82	120	82
Weighted average number of shares used in calculating diluted net income per share	31,349	31,489	31,518	31,455
Effect of stock-based compensation plans that were not included in the computation of diluted earnings per share because to do so would have been antidilutive
Average market price of common stock used for calculation of dilutive shares	$ 20.22	$ 25.32	$ 22.08	$ 24.57
Basic	$ (1.08)	$ 0.28	$ 0.42	$ 0.82
Diluted	$ (1.08)	$ 0.28	$ 0.42	$ 0.81