Income Taxes Level 4 (Details) - Summary of the Valuation Allowance - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Line Items]
Disallowed interest expense carryforward	$ 34		$ 283
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	120	$ 547	522	$ 651
Changes in Related Gross Deferred Tax Assets/Liabilities	0	0	0	0
Charge	20	$ (427)	25	(129)
Balance at End of Period	$ 140		$ 547	$ 522