Restructuring and Other Related Charges (Narrative) (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) employee	Jun. 30, 2020 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 22	$ 28	$ 42	$ 72
T21
Restructuring Cost and Reserve [Line Items]
Expected number of positions eliminated | employee			140
Number of positions eliminated | employee			120
Expected cost remaining	$ 40		$ 40
Restructuring expenses			12
T21 | Personnel
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			10
Limited Voluntary Opportunity Plan (“LVOP”) | Personnel
Restructuring Cost and Reserve [Line Items]
Restructuring expenses			$ 17	$ 18