Summary Of Significant Accounting Policies (Schedule Of Supplemental Net Income Per Common 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
Accounting Policies [Abstract]
Net income (loss)	$ 28,504	$ 7,742	$ 37,927	$ 8,477
Basic weighted average common shares outstanding (in shares)	39,596	38,898	39,520	38,841
Effect of dilutive instruments	446	599	467	609
Diluted weighted average common shares outstanding (in shares)	40,042	39,497	39,987	39,450
Basic (in dollars per share)	$ 0.72	$ 0.20	$ 0.96	$ 0.22
Diluted (in dollars per share)	$ 0.71	$ 0.20	$ 0.95	$ 0.21