Shareholder's Equity (Narrative) (Details) (USD $)	0 Months Ended		9 Months Ended
	Apr. 24, 2012 Y	Oct. 20, 2010 Y	Sep. 30, 2012	Sep. 30, 2011
Number of shares, options granted			0	0
Repurchase of common stock, shares			415,084	248,100
Repurchase of common stock			$ 11,838,000	$ 6,185,000
Average price per share			$ 28.50	$ 25.00
Shares repurchased to cover employee tax withholdings			48,139	22,802
Stock repurchased program authorized by the board of directors	40,000,000	40,000,000
Period of stock repurchase program, months	18	18
Number of shares authorized for grant under share incentive plan			2,760,250
Unrecognized compensation cost on non vested awards			$ 8,051,000
Share based payment award shares purchased for award			26,041	1,023,000
Restricted Stock [Member]
Shares available for future grants/issuance under stock incentive plan			933,263
Stock Options [Member]
Options term			10
Shares available for future grants/issuance under stock incentive plan			1,069,084
Outside Directors [Member] | Restricted Stock [Member]
Vesting period			1 year	2 years
Employees [Member] | Restricted Stock [Member]
Number of installments in restricted stock granted			3
Vesting period			4 years
Unrecognized compensation cost on non vested awards, weighted average period of recognition			1 year 2 months
Employees [Member] | Stock Options [Member]
Vesting period			4 years