RETIREMENT AND OTHER BENEFIT PROGRAMS - Summary of Pre-Tax losses Included in AOCI (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Pension benefits
Summary of the pre-tax losses included in AOCI
Actuarial loss (gain)	$ 1,025	$ 1,607
Prior service credit and transition obligation	(9)	(10)
Total pre-tax loss (gain) recognized in AOCI	1,016	1,597
OPEB
Summary of the pre-tax losses included in AOCI
Actuarial loss (gain)	(41)	(79)
Prior service credit and transition obligation	(59)	(74)
Total pre-tax loss (gain) recognized in AOCI	$ (100)	$ (153)

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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