Stockholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	4 Months Ended	12 Months Ended
	Sep. 30, 2018	Jul. 05, 2018	Dec. 31, 2017	Sep. 21, 2018	Sep. 25, 2017	Mar. 02, 2017
Stockholders' Equity Attributable to Parent [Abstract]
Stock Repurchase Program, Authorized Amount				$ 100.0	$ 25.0	$ 30.0
Stock Repurchased During Period, Shares	0.6	8.7	13.3
Stock Repurchased During Period, Value	$ 1.4	$ 25.0	$ 30.0
Treasury Stock Acquired, Average Cost Per Share	$ 2.44	$ 2.86	$ 2.25