Annual report pursuant to Section 13 and 15(d)

COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Fair Value Measurement of Plan Assets Using Unobservable Inputs (Detail)

v3.10.0.1
COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Fair Value Measurement of Plan Assets Using Unobservable Inputs (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year $ 43,448  
Actual Return on Assets:    
Fair value of plan assets at end of year 40,864 $ 43,448
Fair Value, Inputs, Level 3    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 8  
Actual Return on Assets:    
Fair value of plan assets at end of year 6 8
Fair Value, Inputs, Level 3 | Corporate Bonds    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 8 0
Actual Return on Assets:    
Assets Held at End of Year 0 0
Assets Sold During the Year (7) 0
Purchases 11 9
Sales (10) (1)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 2 8
Fair Value, Inputs, Level 3 | Hedge Funds    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 0 0
Actual Return on Assets:    
Assets Held at End of Year 0 0
Assets Sold During the Year 0 0
Purchases 9 0
Sales (5) 0
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 4 0
Fair Value, Inputs, Level 3 | Structured Products    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 8 0
Actual Return on Assets:    
Assets Held at End of Year 0 0
Assets Sold During the Year (7) 0
Purchases 20 9
Sales (15) (1)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year $ 6 $ 8