Shareholders'Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		1 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Jan. 31, 2013 2013 Stock Repurchase Program	Mar. 31, 2013 2013 Stock Repurchase Program
Number of shares authorized to be repurchased under the current open-market stock repurchase program			10,000,000
Repurchase of stock program, period			2 years
Number of shares repurchased under the current open-market stock repurchase program				1,243,561
Payments for shares repurchased under the current open-market stock repurchase program (in dollars)	$ 85,300	$ 81,885		$ 85,300
Quarter dividend paid, per share (in dollars per share)	$ 0.105
Dividend paid (in dollars)		2,448
Dividends declared	$ 16,755	$ 17,049