Stock Option Plans and Stock Based Compensation Level 4 (Details) - Restricted Unit Activity - USD ($) $ / shares in Millions, $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2018
Schedule of Restricted Stock [Line Items]
Non-cash stock based compensation expense	$ 8	$ 0	$ 17	$ 0
Restricted Stock Units (RSUs) [Member]
Schedule of Restricted Stock [Line Items]
Grant Date Fair Value	$ 16
Restricted Stock Units (RSUs) [Member] | Award Date: March 2020
Schedule of Restricted Stock [Line Items]
Grant Date Fair Value			$ 11
Restricted Stock Units (RSUs) [Member] | Award Date: August 2020
Schedule of Restricted Stock [Line Items]
Grant Date Fair Value			1
Restricted Stock Units (RSUs) [Member] | Award Date: January 2020
Schedule of Restricted Stock [Line Items]
Grant Date Fair Value			$ 2
Number of Shares Vested			36,666
Restricted Stock Units (RSUs) [Member] | September 2019 | Share-based Payment Arrangement, Employee | HHC 2019 Omnibus Incentive Plan
Schedule of Restricted Stock [Line Items]
Number of Shares Vested			344,700
Performance Shares
Schedule of Restricted Stock [Line Items]
Grant Date Fair Value	$ 29		$ 13