Net Income Per Share (Computation Of Weighted Average Shares Outstanding Basic And Diluted) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net income per common share:
Common shares	25,355,000	25,547,000	25,447,000	26,186,000
Vested restricted stock units	571,000	428,000	546,000	396,000
Basic number of weighted average shares outstanding	25,926,000	25,975,000	25,993,000	26,582,000
Dilutive effect of stock options	48,000	105,000	53,000	140,000
Dilutive effect of restricted stock and restricted stock units	6,000	31,000	37,000	74,000
Dilutive number of weighted average shares outstanding	25,980,000	26,111,000	26,083,000	26,796,000
Restricted stock outstanding excluded from calculation of diluted net income per share			8,422