Treasury Stock (Details) (USD $)	6 Months Ended				1 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Repurchase Programs	Jun. 30, 2013 Repurchase Programs	Dec. 31, 2013 Repurchase Program 2013	Jan. 31, 2012 Repurchase Program 2012	Jun. 30, 2014 Employee benefit plans repurchases	Jun. 30, 2013 Employee benefit plans repurchases
Shares repurchased in connection with:
Common stock authorized for repurchase					$ 100,000,000	$ 300,000,000
Total	$ 113,420,000	$ 27,118,000	$ 100,000,000	$ 18,122,000			$ 13,420,000	$ 8,996,000
Total (in shares)	1,281,500	368,600	1,149,200	237,900			132,300	130,700