Stockholders' Equity (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	May 31, 2019
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount				$ 250.0
Stock Repurchased and Retired During Period, Value	$ (20.0)		$ (58.1)
Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Shares	(0.3)	0.0	(1.1)
Stock Repurchased and Retired During Period, Value	$ 0.0		$ 0.0
Additional Paid-in Capital [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	(3.9)		(13.2)
Retained Earnings [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Value	$ (16.1)		$ (44.9)