Leasing (Lease, Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases [Abstract]
Operating lease expense	$ 10	$ 11	$ 36	$ 35
Variable lease expense	2	2	6	6
Total lease expense, net	$ 12	$ 13	$ 42	$ 41