Earnings Per Share (Schedule Computing Earnings Per Share and Weighted Average Number of Shares) Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share [Abstract]
Net income/(loss) available to common shareholders	$ (7,379)	$ (33,745)	$ 4,132	$ 13,296
Weighted average number of shares used in calculating basic net income/(loss) per share	31,628	31,349	31,562	31,329
Stock options			125	69
Long-term incentive plan			169	120
Weighted average number of shares used in calculating diluted net income/(loss) per share	31,628	31,349	31,856	31,518
Average market price of common stock used for calculation of dilutive shares	$ 30.59	$ 20.22	$ 28.53	$ 22.08
Basic	$ (0.23)	$ (1.08)	$ 0.13	$ 0.42
Diluted	$ (0.23)	$ (1.08)	$ 0.13	$ 0.42