Pension and Other Postretirement Benefits - Schedule of Fair Value of Pension Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	$ 2,426	$ 4,264
Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	704	1,166
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	551	881
Long/Short Equity Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	8	4
Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	145	281
Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,392	2,741
Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,236	2,505
Cash and Cash Equivalent Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	156	236
Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	330	357
Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	302	326
Other Investments, Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	28	31
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	519	1,164
Level 1 [Member] | Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	71	210
Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	71	210
Level 1 [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	428	891
Level 1 [Member] | Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	390	827
Level 1 [Member] | Cash and Cash Equivalent Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	38	64
Level 1 [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	20	63
Level 1 [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	20	63
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	426	1,027
Level 2 [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	426	1,027
Level 2 [Member] | Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	426	1,027
Net Asset Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	1,481	2,073
Net Asset Value [Member] | Equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	633	956
Net Asset Value [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	480	671
Net Asset Value [Member] | Long/Short Equity Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	8	4
Net Asset Value [Member] | Private Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	145	281
Net Asset Value [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	538	823
Net Asset Value [Member] | Intermediate and Long Duration Government Credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	420	651
Net Asset Value [Member] | Cash and Cash Equivalent Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	118	172
Net Asset Value [Member] | Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	310	294
Net Asset Value [Member] | Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	282	263
Net Asset Value [Member] | Other Investments, Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension and other postretirement plans' assets	$ 28	$ 31