Commitments and Contingencies (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	2 Months Ended	9 Months Ended	12 Months Ended		35 Months Ended
	Oct. 21, 2014	Dec. 31, 2011	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Jul. 24, 2013	Oct. 25, 2011
Commitments and Contingencies
Amount authorized under stock repurchase plan							$ 300	$ 200
Total number of Shares Purchased	358,128	671,776	2,453,224	1,159,871	459,252	4,744,123
Average Price Paid per Share (in dollars per share)		$ 48.72	$ 57.97	$ 51.83	$ 50.27
Aggregate Cost	$ 19.6	$ 32.7	$ 142.2	$ 60.1	$ 23.1	$ 258.1