Shareholder's Equity (Narrative) (Details) (USD $)	0 Months Ended		12 Months Ended
	Apr. 24, 2012 M	Oct. 20, 2010 M	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Repurchase of common stock, shares			415,084	344,100
Repurchase of common stock			$ 11,838,000	$ 8,584,000
Average price per share			$ 28.50	$ 24.92
Amout of repurchased shares to cover employee tax withholdings			1,263,000	1,423,000
Shares repurchased to cover employee tax withholdings			48,139	62,700
Stock repurchased program authorized by the board of directors	40,000,000	40,000,000
Period of stock repurchase program, months	18	18
Unrecognized compensation cost on non vested awards			$ 6,382,000
Employee Service Share-based Compensation, Nonvested Awards			1 year 1 month 6 days
Share based payment award shares purchased for award			20,000	923,000	2,400,000
Outside Directors [Member]
Number of installments in restricted stock granted.			3
Portion of restricted stock vested outside directors			33.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			1 year	2 years
Number of years restricted for trade					5
Employees [Member]
Number of installments in restricted stock granted.			3
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			4 years
Options term			10
Stock Options [Member]
Number of shares authorized for grant under share incentive plan			2,760,250
Shares available for future grants/issuance under stock incentive plan			1,069,084
Restricted Stock [Member]
Shares available for future grants/issuance under stock incentive plan			906,972