Leases Lease Cost and Supplemental Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2020
Leases [Abstract]
Operating lease expense	$ 18	$ 16	$ 29
Short-term lease expense	2	5	5
Amortization expense	1	1	2
Variable lease expense	3	2	3
Cash paid for finance leases	2	2	4
Right-of-use assets obtained in exchange for operating lease	2	1	13
Right-of-use assets obtained in exchange for finance lease obligations	$ 0	$ 3	$ 5
Operating Lease, Weighted Average Remaining Lease Term	10 years 8 months 12 days		10 years
Finance Lease, Weighted Average Remaining Lease Term	1 year 8 months 12 days		4 years 9 months 18 days
Lessee, Operating Lease, Discount Rate	5.74%		5.24%
Lessee, Finance Lease, Discount Rate	10.00%		7.73%