Common Stock and Stock-Based Compensation Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Oct. 23, 2020
Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount				$ 250.0
Treasury Stock, Value, Acquired, Cost Method	$ 36.8		$ 35.4
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 145.4	$ 182.2
Total Shares Repurchased Under Program	4,266,782
Total Shares Repurchased Under Program, Value	$ 104.6
Share-based Payment Arrangement, Cash Used to Settle Award	$ 2.9
Treasury Stock [Member]
Share Repurchases [Line Items]
Treasury Stock, Shares, Acquired	1,291,860	2,974,922	1,900,000
Treasury Stock, Value, Acquired, Cost Method	$ 36.8	$ 67.8	$ 35.4