Leases Lease Cost (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 13, 2019	Dec. 31, 2020	Dec. 31, 2018
Leases [Abstract]
Operating Lease, Expense	$ 5	$ 109	$ 76
Short-term Lease, Cost	5	91	63
Operating Leases, Rent Expense	10	200	139	$ 187
Finance Lease, Right-of-Use Asset, Amortization	1	11	15
Sublease Income	(1)	(6)	(6)
Lease, Cost	$ 10	$ 205	$ 148