Restructuring Activities - Summary of Changes in Liabilities for Restructuring Activities (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017
Restructuring And Related Activities [Abstract]
Beginning Balance		$ 68		$ 58	$ 73
Reclassification of ASC 420 real estate restructuring to right-of -use asset	[1]	(22)
Charges		62	[2]	139	80
Non cash charges and other adjustments		1		(2)	2
Payments		(74)		(127)	(97)
Ending Balance		$ 35		$ 68	$ 58

[1] Upon adoption of ASC 842, the real estate operating lease ASC 420 liabilities were reclassified and presented as a reduction of the related operating lease right-of-use asset.

[2] Excludes charges related to operating lease right-of-use assets of $18 million. Includes $6 million of adjustments related to changes in previous productivity initiatives.