Supplementary Data Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Feb. 13, 2015	Feb. 14, 2014
Equity [Abstract]
Stock Repurchase Program, Additional Amount Authorized			$ 300.0	$ 300.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 271.3
Number of shares repurchased	8.5	8.3
Aggregate cost, including fees	$ 172.3	$ 148.1
Average price per share, including fees	$ 20.36	$ 17.91