Supplementary Data Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Feb. 12, 2016	Feb. 13, 2015
Share Repurchase Program [Abstract]
Stock Repurchase Program, Authorized Amount			$ 300.0	$ 300.0
Number of shares repurchased	2.5	2.5
Aggregate cost, including fees	$ 53.7	$ 51.2
Average price per share, including fees	$ 21.67	$ 20.84
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 404.9