Earnings Per Share (Summary Of Basic And Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ (27,776)	$ 12,009	$ (24,065)	$ 37,905
Less: adjustment for income allocated to participating securities		(1,684)		(5,229)
Net income attributable to common stockholders - basic and diluted	$ (27,776)	$ 10,325	$ (24,065)	$ 32,676
Weighted average common shares outstanding - basic	74,322	84,659	76,318	86,582
Plus: dilutive effect of stock options and unvested restricted stock units		778		1,137
Weighted average common shares outstanding - diluted	74,322	85,437	76,318	87,719
Basic	$ (0.37)	$ 0.12	$ (0.32)	$ 0.38
Diluted	$ (0.37)	$ 0.12	$ (0.32)	$ 0.37