Shareholder's Equity (Narrative) (Details) (USD $)	0 Months Ended		12 Months Ended
	Oct. 20, 2010 M	Apr. 22, 2009 M	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Repurchase of common stock, shares			344,100		830,700
Repurchase of common stock			$ 8,584,000		$ 12,587,000
Average price per share			$ 24.92		$ 15
Amout of repurchased shares to cover employee tax withholdings			1,423,000
Shares repurchased to cover employee tax withholdings			62,700
Stock repurchased program authorized by the board of directors	40,000,000	40,000,000	40,000,000		25,000,000
Period of stock repurchase program, months	18	18
Number of shares authorized for grant under share incentive plan			2,760,250
Shares available for future grants/issuance under stock incentive plan			1,296,301
Unrecognized compensation cost on non vested awards			$ 5,938,000
Unrecognized compensation cost on non vested awards, weighted average period of recognition			1.1
Share based payment award shares purchased for award			922,801	2,384,000	2,457,000
Outside Directors [Member]
Number of installments in restricted stock granted to outside directors			3
Portion of restricted stock vested outside directors			33.00%
Vesting period			2
Number of years restricted for trade			5
Employees [Member]
Additional options granted under stock incentive plan			0	0	0
Vesting period			4	4	4
Options term			10
Restricted Stock [Member]
Shares available for future grants/issuance under stock incentive plan			538,126