RETIREMENT BENEFITS - Pension Plan Assets at Fair Value (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	$ 1,173	$ 1,162
Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	93	89
Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	386	395
Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	14	4	$ 0
Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	680	674
Cash and cash equivalent
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	38	12
Cash and cash equivalent | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	12
Cash and cash equivalent | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	38	0
Cash and cash equivalent | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Cash and cash equivalent | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	360	397
Fixed income | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Fixed income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	347	393
Fixed income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	13	4
Fixed income | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Domestic equity - large cap
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	394	339
Domestic equity - large cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	20
Domestic equity - large cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1	1
Domestic equity - large cap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Domestic equity - large cap | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	393	318
International equity
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	202	229
International equity | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	78	46
International equity | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
International equity | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1	0
International equity | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	123	183
Domestic equity - mid cap
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		1
Domestic equity - mid cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		0
Domestic equity - mid cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		1
Domestic equity - mid cap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		0
Domestic equity - mid cap | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		0
Domestic equity - small cap
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	60	64
Domestic equity - small cap | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	1	11
Domestic equity - small cap | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Domestic equity - small cap | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Domestic equity - small cap | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	59	53
Other (hedge funds, private equity, real estate, commodities)
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	119	120
Other (hedge funds, private equity, real estate, commodities) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	14	0
Other (hedge funds, private equity, real estate, commodities) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Other (hedge funds, private equity, real estate, commodities) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	0	0
Other (hedge funds, private equity, real estate, commodities) | Assets Valued at NAV Practical Expedient
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	$ 105	$ 120