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, 2021	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Components of Benefit From (Provision For) Income Taxes:
Texas Margin Tax	[1]		$ (9.6)	$ (7.2)		$ (37.0)	$ (21.9)
Other			0.3	5.0		(0.2)	2.5
Benefit from (provision for) income taxes			(16.1)	19.1		(57.3)	138.6
OTA Holdings, Inc. [Member]
Components of Benefit From (Provision For) Income Taxes:
Benefit from (provision for) income taxes		$ 72.2	$ (6.8)	$ 21.3	$ 85.8	$ (20.1)	$ 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.