Income Taxes, Benefit from (provision for) income taxes (Details) - USD ($) $ in Millions			3 Months Ended		7 Months Ended	9 Months Ended
		Mar. 05, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Components of Benefit From (Provision For) Income Taxes:
Texas Margin Tax	[1]		$ (7.2)	$ (15.5)		$ (21.9)	$ (36.5)
Other			5.0	0.1		2.5	(0.9)
Benefit from (provision for) income taxes			19.1	$ (15.4)		138.6	$ (37.4)
OTA Holdings, Inc. [Member]
Components of Benefit From (Provision For) Income Taxes:
Benefit from (provision for) income taxes		$ 72.2	$ 21.3		$ 85.8	$ 158.0

[1] Although the Texas Margin Tax is not considered a state income tax, it has the characteristics of an income tax since it is determined by applying a tax rate to a base that considers our Texas-sourced revenues and expenses.