Supplementary Data Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Equity [Abstract]
Number of shares repurchased	4.9	(5.6)
Aggregate cost, including fees	$ 102.0	$ 97.3
Average price per share, including fees	$ 20.87	$ 17.51
Stock Repurchase Program, Authorized Amount	$ 300.0	$ 300.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 341.6