Annual report pursuant to Section 13 and 15(d)

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

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COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Fair Value Measurement of Plan Assets Using Unobservable Inputs (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year $ 30,129  
Actual Return on Assets:    
Fair value of plan assets at end of year 30,031 $ 30,129
Fair Value, Inputs, Level 3    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 7,977 7,260
Actual Return on Assets:    
Assets Held at End of Year 39 245
Assets Sold During the Year 231 140
Purchases 1,327 2,402
Sales (1,306) (2,070)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 8,268 7,977
Fair Value, Inputs, Level 3 | Corporate Bonds    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 269 223
Actual Return on Assets:    
Assets Held at End of Year (8) 0
Assets Sold During the Year 0 0
Purchases 22 108
Sales (4) (62)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 279 269
Fair Value, Inputs, Level 3 | Hedge Funds    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 3,595 3,738
Actual Return on Assets:    
Assets Held at End of Year 62 71
Assets Sold During the Year 39 (9)
Purchases 283 1,043
Sales (362) (1,248)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 3,617 3,595
Fair Value, Inputs, Level 3 | Structured Products(1)    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 1,307 1,091
Actual Return on Assets:    
Assets Held at End of Year 79 104
Assets Sold During the Year 45 23
Purchases 545 350
Sales (409) (261)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 1,567 1,307
Fair Value, Inputs, Level 3 | Private Equity    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 1,323 1,397
Actual Return on Assets:    
Assets Held at End of Year (39) 11
Assets Sold During the Year 149 126
Purchases 347 166
Sales (365) (377)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 1,415 1,323
Fair Value, Inputs, Level 3 | All Other Corporate Bonds [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 613 0
Actual Return on Assets:    
Assets Held at End of Year 11 0
Assets Sold During the Year (2) 0
Purchases 130 735
Sales (166) (122)
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 586 613
Fair Value, Inputs, Level 3 | Risk Parity Funds [Domain]    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 817 756
Actual Return on Assets:    
Assets Held at End of Year (62) 61
Assets Sold During the Year 0 0
Purchases 0 0
Sales 0 0
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year 755 817
Fair Value, Inputs, Level 3 | Other Investments [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Fair value of plan assets at beginning of year 53 55
Actual Return on Assets:    
Assets Held at End of Year (4) (2)
Assets Sold During the Year 0 0
Purchases 0 0
Sales 0 0
Transfers Into (Out of) Level 3 0 0
Fair value of plan assets at end of year $ 49 $ 53