Shareholders' Equity (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended						3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Restricted Stock Issued Prior To 2011 [Member]	Jun. 30, 2012 Restricted Stock Issued Since 2011 [Member]	Jun. 30, 2012 Stock Awards Cliff Vested [Member]	Jun. 30, 2012 Stock Awards Time Vested [Member]	Jun. 30, 2012 Restricted Stock Units (RSU's) [Member]	Jun. 30, 2011 Restricted Stock Units (RSU's) [Member]	Jun. 30, 2012 Restricted Stock Units (RSU's) [Member]	Sep. 30, 2011 Restricted Stock Units (RSU's) [Member]	Jun. 30, 2012 Restricted Shares [Member]	Jun. 30, 2011 Restricted Shares [Member]	Jun. 30, 2012 Restricted Shares [Member]	Jun. 30, 2011 Restricted Shares [Member]	Jun. 30, 2012 Stock Options [Member]
Shareholders Equity and Share-Based Payments [Line Items]
Compensation cost	$ 1,000,000	$ 868,000	$ 1,942,000	$ 1,987,000
Total income tax benefit recognized related to stock-based compensation	410,000	347,000	777,000	795,000
Total intrinsic value of options exercised	9,000	32,000	17,000	147,000
Cash received from exercise of stock options	58,000	97,000	78,000	309,000
Stock options granted in the period			0
Vesting period of stock awards					5 years	3 years	3 years	4 years
Total fair value of restricted stock shares/units vested and released										0		677,000	142,000	114,000	1,700,000	765,000
Restricted stock units vested and released during the period									0		0
Total unrecognized compensation cost related to nonvested stock awards									765,000		765,000		6,000,000		6,000,000		2,100,000
Expected recognized over a weighted-average period, years											1 year 9 months 18 days				2 years 4 months 24 days		2 years
Income tax benefits received	60,000	58,000	685,000	633,000
Tax deficiency from stock options exercised			$ 45,000	$ 251,000