Strategic Initiatives - Restructuring Liability (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	$ 56	$ 33
Restructuring costs accrued during the period	7	2
Restructuring costs paid during the period	(23)	(11)
Restructuring liability at end of period	40	24
Severance and Other Employee Costs
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	10	10
Restructuring costs accrued during the period	0	0
Restructuring costs paid during the period	(8)	(8)
Restructuring liability at end of period	2	2
Lease Termination and Associated Costs
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	46	23
Restructuring costs accrued during the period	0	0
Restructuring costs paid during the period	(8)	(1)
Restructuring liability at end of period	38	22
Other
Restructuring Reserve [Roll Forward]
Restructuring liability at beginning of period	0	0
Restructuring costs accrued during the period	7	2
Restructuring costs paid during the period	(7)	(2)
Restructuring liability at end of period	$ 0	$ 0