Stockholders' Equity (Details 2) - USD ($) shares in Millions, $ in Millions	3 Months Ended							9 Months Ended		12 Months Ended		21 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Feb. 13, 2019	Aug. 01, 2018
Equity [Abstract]
Stock Repurchase Program, Authorized Amount													$ 1,000.0	$ 500.0
Stock Repurchased and Retired During Period, Shares	0.0	0.0	2.6	1.9	1.5	2.7	1.5	2.6	5.7	7.6	10.9	10.2
Stock Repurchased and Retired During Period, Value			$ 100.0	$ 87.0	$ 72.0	$ 118.0	$ 60.0	$ 100.0	$ 250.0	$ 337.0	$ 500.0	$ 437.0
stock repurchase accrued but unpaid					$ 2.0				$ 2.0		$ 33.0
Treasury Stock, Shares, Retired							10.9