Capital Stock Repurchase Plan Transactions (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Feb. 28, 2013
Capital Stock Repurchase Plan Transactions [Abstract]
Stock repurchase program, amount authorized					$ 100
Shares repurchased	300,000	280,701	682,934	280,701
Weighted average price per share	$ 85.04	$ 65.72	$ 85.65	$ 65.72
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 63.3		$ 63.3