Income Taxes Unrecognized Benefits (Details) - USD ($)	3 Months Ended	9 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	$ (2,000,000)		$ (2,000,000)	$ (2,000,000)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	21,000,000		21,000,000
Unrecognized Tax Benefits That Would Not Impact Effective Tax Rate	3,000,000		3,000,000
Unrecognized Tax Benefits	24,000,000		24,000,000
Tax Benefits Associated With Nol And Tax Credit Carryforwards	11,000,000		11,000,000
Decrease in Unrecognized Tax Benefits is Reasonably Possible	15,000,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	0		$ 0
Unrecognized Tax Benefits, Interest on Income Taxes Expense	$ 0	$ 0