Capital Stock Repurchase Plan Transactions (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Capital Stock Repurchase Plan Transactions [Abstract]
Shares repurchased		1,032,754	9,334	1,313,455	209,234
Weighted average price per share		$ 68.91	$ 62.75	$ 68.23	$ 56.03
Stock Repurchase Program, Authorized Amount	$ 100
Stock Repurchase Program, Remaining Authorized Repurchase Amount				$ 25.1