Capital Stock (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended			1 Months Ended
	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 31, 2014 Subsequent event	Jul. 31, 2013 Maximum	Dec. 31, 2012 Maximum
Capital Stock
Additional authorized amount of outstanding common stock to be repurchased							$ 150	$ 50
Authorized amount to repurchase outstanding common stock	40
Aggregate shares repurchased	896,653	1,573,588	2,600,000	300,000	500,000
Total cost of shares repurchased		$ 50.0	$ 89.5	$ 8.1	$ 4.9
Repurchased shares settled						148,990