Significant Accounting Policies (Schedule Of Earnings Per Share) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Earnings Per Share
Number of common shares outstanding at end of period-basic	40,057,747	39,822,000	40,057,747	39,822,000	40,041,746
Effect of using weighted average common shares outstanding		(3,000)	(4,000)	(48,000)
Weighted average basic common shares outstanding-basic	40,058,000	39,819,000	40,054,000	39,774,000
Dilutive effect of common stock options	254,000	204,000	262,000	220,000
Weighted average diluted common shares outstanding-diluted	40,312,000	40,023,000	40,316,000	39,994,000