Employee Benefit and Retirement Plans - Composition of Domestic Pension Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
United States
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	$ 1,161	$ 1,228
United States | Equity securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	273	233
United States | Fixed income securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	760	730
United States | Alternative investments
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	104	239
United States | Cash and other
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	24	26
Level 1 | United States
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	449	457
Level 1 | United States | Equity securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 1 | United States | Fixed income securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	441	400
Level 1 | United States | Alternative investments
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	47
Level 1 | United States | Cash and other
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	8	10
Level 2 | United States
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	15	15
Level 2 | United States | Equity securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | United States | Fixed income securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | United States | Alternative investments
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 2 | United States | Cash and other
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	15	15
Level 3
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	10	9	$ 10
Level 3 | United States
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	1	1
Level 3 | United States | Equity securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | United States | Fixed income securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | United States | Alternative investments
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Level 3 | United States | Cash and other
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	1	1
Subtotal | United States
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	465	473
Subtotal | United States | Equity securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	0
Subtotal | United States | Fixed income securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	441	400
Subtotal | United States | Alternative investments
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	0	47
Subtotal | United States | Cash and other
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	24	26
NAV-based assets | United States
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	696	755
NAV-based assets | United States | Equity securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	273	233
NAV-based assets | United States | Fixed income securities and funds
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	319	330
NAV-based assets | United States | Alternative investments
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	104	192
NAV-based assets | United States | Cash and other
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Defined benefit plan, fair value of plan assets	$ 0	$ 0