Pension and Other Postretirement Benefits - Additional Information (Detail)			1 Months Ended				12 Months Ended
	Dec. 31, 2018 USD ($) Employee Participant	Jan. 17, 2018 Employee	Sep. 30, 2018 USD ($) Participant	Aug. 31, 2018 USD ($) Participant Retiree	May 31, 2018 USD ($)	Apr. 30, 2018 USD ($) Participant Retiree	Dec. 31, 2019	Dec. 31, 2018 USD ($) Employee Participant	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Aug. 01, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of employees affected the change in defined contribution plans | Participant	20,600							20,600
Company's contribution								$ 725,000,000
Lump sum settlements in plan assets on pension and other postretirement benefits	$ 13,000,000
Settlement gain (charge) on net pension and other postretirement benefits								$ 341,000,000
Defined benefit plan, percentage of combined net unfunded									65.00%
Defined benefit plan, description of basis used to determine overall expected long-term rate-of-return on assets assumption								The expected long-term rate of return on plan assets is generally applied to a five-year market-related value of plan assets (a four-year average or the fair value at the plan measurement date is used for certain non-U.S. plans)
Health care cost trend rate assumed for next year	5.50%							5.50%	5.50%	5.50%
Health care cost trend rate	4.50%							4.50%	4.50%	4.50%
Number of years over actual annual health care cost trend experience								3 years
Cash contribution to pension plans								$ 992,000,000	$ 106,000,000	$ 66,000,000
Expected minimum required cash contribution to pension plans, next year								310,000,000
Additions to debt (original maturities greater than three months					$ 492,000,000			560,000,000	21,000,000	1,228,000,000
Cash on hand	$ 128,000,000							128,000,000
Maturity of debt instrument					10 years
Expenses related to saving and investment plans								69,000,000	$ 65,000,000	57,000,000
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Company's contribution								620,000,000
Expected minimum required cash contribution to pension plans, next year								270,000,000
Canada [Member]
Defined Benefit Plan Disclosure [Line Items]
Company's contribution								$ 105,000,000
Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected asset class mix percentage	30.00%							30.00%
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected asset class mix percentage	50.00%							50.00%
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected asset class mix percentage	20.00%							20.00%
Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected long term rate of return on plan assets							6.59%
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Average duration refined yield curve model parallels the plans, years								11 years
Health care cost trend rate	0.80%							0.80%
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	(0.50%)							(0.50%)
Action# 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees affected the change in defined contribution plans	800	800						800
Percentage of employers contribution in defined benefit plans		3.00%
Weighted average discount rate	3.80%							3.80%	3.65%
Action# 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees affected the change in defined contribution plans | Participant	700							700
Weighted average discount rate	3.43%							3.43%	3.29%
Action# 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees affected the change in defined contribution plans | Participant	2,100							2,100
Defined benefit plan, number of participants reduced | Retiree						2,100
Benefit obligation of retirement plans						$ 560,000,000
Defined benefit pension plans, transaction fee						23,000,000
Company's contribution						$ 89,000,000
Defined benefit plan, number of participants before transaction | Participant						3,500
Settlement gain (charge) on net pension and other postretirement benefits								$ 167,000,000
Weighted average discount rate	3.60%							3.60%	3.43%
Action# 3 [Member] | Canada [Member]
Defined Benefit Plan Disclosure [Line Items]
Company's contribution								$ 89,000,000
Action# 4 [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees affected the change in defined contribution plans | Participant	11,500							11,500
Defined benefit plan, number of participants reduced | Retiree				10,500
Benefit obligation of retirement plans				$ 287,000,000
Defined benefit pension plans, transaction fee				$ 10,000,000
Defined benefit plan, number of participants before transaction | Participant				43,400
Defined benefit plan, additional number of participants reduced | Retiree				1,000
Lump sum settlements in plan obligations on pension and other postretirement benefits				$ 75,000,000
Lump sum settlements in plan assets on pension and other postretirement benefits				$ 85,000,000
Settlement gain (charge) on net pension and other postretirement benefits								$ 230,000,000
Weighted average discount rate	4.39%							4.39%	3.70%
Action# 5 [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees affected the change in defined contribution plans | Participant	5,500		5,500					5,500
Settlement gain (charge) on net pension and other postretirement benefits			$ 23,000,000					$ (56,000,000)
Weighted average discount rate	4.35%							4.35%	3.61%
New Direct Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average discount rate											3.48%
Pension and other postretirement benefit plan unfunded status											$ 2,348,000,000
Pension and other postretirement benefit plan current liability											136,000,000
Pension and other postretirement benefit plan noncurrent liability											2,392,000,000
Pension and other postretirement benefit plan accumulated other comprehensive loss											2,704,000,000
Additional New Direct Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and other postretirement benefit plan unfunded status											$ 180,000,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees covered under defined benefit plans | Employee	54,000							54,000
Settlement gain (charge) on net pension and other postretirement benefits								$ (410,000,000)	$ (5,000,000)	$ (16,000,000)
Weighted average discount rate	4.21%							4.21%	3.68%
Pension and other postretirement benefit plan current liability	$ 10,000,000							$ 10,000,000	$ 11,000,000
Pension and other postretirement benefit plan noncurrent liability	$ 1,407,000,000							$ 1,407,000,000	$ 2,341,000,000
Rate of compensation increase	3.26%							3.26%	3.28%
Expected long term rate of return on plan assets								6.89%	7.47%	7.31%
Expenses related to saving and investment plans										$ 25,000,000
Pension Benefits [Member] | Scenario Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase							3.26%
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of employees covered under defined benefit plans | Employee	48,000							48,000
Company's contribution								$ 8,000,000	$ 8,000,000	6,000,000
Settlement gain (charge) on net pension and other postretirement benefits								$ 56,000,000
Weighted average discount rate	4.25%							4.25%	3.54%
Pension and other postretirement benefit plan current liability	$ 105,000,000							$ 105,000,000	$ 118,000,000
Pension and other postretirement benefit plan noncurrent liability	$ 868,000,000							$ 868,000,000	$ 1,100,000,000
Expenses related to saving and investment plans										$ 8,000,000