Charges and Credits - Summary of Charges and Credits (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Jun. 30, 2024
Charges And Credits [Line Items]
Charges and credits, Pretax Charge				$ 167,000,000
Charges and credits, Tax Benefit				28,000,000
Charges and credits, Noncontrolling Interests				13,000,000
Charges and credits, Net			$ 0	$ 126,000,000
Interest And Other | Workforce reductions
Charges And Credits [Line Items]
Charges and credits, Pretax Charge	$ 111,000,000
Charges and credits, Tax Benefit	17,000,000
Charges and credits, Net	94,000,000
Interest And Other | Merger & integration
Charges And Credits [Line Items]
Charges and credits, Pretax Charge	31,000,000	$ 25,000,000
Charges and credits, Tax Benefit	5,000,000	6,000,000
Charges and credits, Noncontrolling Interests	8,000,000	5,000,000
Charges and credits, Net	$ 18,000,000	$ 14,000,000