Strategic Initiatives - Restructuring Liability (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	$ 40	$ 24	$ 56	$ 33
Restructuring costs accrued during the period	15	39	22	41
Restructuring costs paid during the period	(19)	(11)	(42)	(22)
Restructuring liability at end of period	36	52	36	52
Severance and Other Employee Costs
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	2	2	10	10
Restructuring costs accrued during the period	4	5	4	5
Restructuring costs paid during the period	(4)	(1)	(12)	(9)
Restructuring liability at end of period	2	6	2	6
Lease Termination and Associated Costs
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	38	22	46	23
Restructuring costs accrued during the period	0	30	0	30
Restructuring costs paid during the period	(4)	(6)	(12)	(7)
Restructuring liability at end of period	34	46	34	46
Other
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	0	0	0	0
Restructuring costs accrued during the period	11	4	18	6
Restructuring costs paid during the period	(11)	(4)	(18)	(6)
Restructuring liability at end of period	$ 0	$ 0	$ 0	$ 0