Stockholders' Equity (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 03, 2020	Oct. 22, 2019	Feb. 13, 2017
Class of Stock [Line Items]
Repurchase of common stock		$ 416.0	$ 85.0	$ 463.6
Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 1,000.0	$ 1,000.0
Repurchase of common stock, shares		3.8	0.7
Subsequent Event [Member]
Class of Stock [Line Items]
Repurchase of common stock	$ 1.6
Subsequent Event [Member] | Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount					$ 1,033.9
Common Stock [Member]
Class of Stock [Line Items]
Repurchase of common stock, shares			0.0