Shareholders' Equity - Share Repurchase and Dividends (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended
	Mar. 24, 2016	Feb. 22, 2016	Mar. 31, 2016	May. 02, 2016	Dec. 31, 2015
Shareholders' Equity
Repurchases to date (in shares)			7,668,905		4,290,527
Repurchases to date			$ 174.1		$ 90.9
Dividend declared (in dollars per share)		$ 0.04	$ 0.04
Dividend paid	$ 6.5		$ 6.5
Target dividend per annum (in dollars per share)			$ 0.16
Repurchase Program
Shareholders' Equity
Amount approved for repurchase of common stock			$ 225.0
Common stock repurchased during the period (in shares)			3,377,858
Aggregate cost of common stock repurchased during the period			$ 83.1
Repurchases to date (in shares)			6,214,900	7,314,900
Repurchases to date			$ 148.1	$ 179.9