Shareholders' Equity - Share Repurchase and Dividends (Details) - USD ($) $ / shares in Units, $ in Millions				3 Months Ended	6 Months Ended
	Jun. 24, 2016	Mar. 24, 2016	Feb. 22, 2016	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Shareholders' Equity
Repurchases to date (in shares)				8,872,450	8,872,450	4,290,527
Repurchases to date				$ 208.7	$ 208.7	$ 90.9
Dividend declared (in dollars per share)			$ 0.04	$ 0.04	$ 0.08
Dividend paid	$ 6.5	$ 6.5			$ 13.0
Target dividend per annum (in dollars per share)					$ 0.16
Repurchase Program
Shareholders' Equity
Amount approved for repurchase of common stock				$ 225.0	$ 225.0
Common stock repurchased during the period (in shares)				1,200,000	4,577,858
Aggregate cost of common stock repurchased during the period				$ 34.5	$ 117.6
Repurchases to date (in shares)				7,414,900	7,414,900
Repurchases to date				$ 182.6	$ 182.6
Remaining authorization amount for repurchase of common stock				$ 42.4	$ 42.4