PENSION AND OTHER POST-EMPLOYMENT BENEFITS - Components of net periodic additional pension benefit cost (Details) $ in Millions, Rp in Billions	12 Months Ended
Dec. 31, 2019 USD ($)	Dec. 31, 2019 IDR (Rp)	Dec. 31, 2018 IDR (Rp)	Dec. 31, 2017 IDR (Rp)
Disclosure of defined benefit plans [line items]
Defined benefit plan actuarial gain (loss) - net of tax	$ 152	Rp 2,109	Rp (4,820)	Rp 2,375
Additional pension benefit obligation
Disclosure of defined benefit plans [line items]
Past service costs				657
Interest costs		1	69
Net periodic pension benefit cost		1	69	657
Experience adjustments		(17)	(773)
Changes in financial assumptions			(175)	419
Return on plan assets (excluding amount included in net interest expense)		5	14
Changes in asset ceiling excluding amount in net interest		5
Defined benefit plan actuarial gain (loss) - net of tax		Rp (7)	Rp (934)	Rp 419
Discount rate	7.25%	7.25%	8.25%	6.75%
Rate of compensation increases	8.00%	8.00%	8.00%	8.00%
Additional pension benefit obligation \| Minimum
Disclosure of defined benefit plans [line items]
Rate of return on investment	9.00	9.00	9.30	9.50
Actuarial discount rate of pension fund	9.25	9.25	9.25	9.25
Additional pension benefit obligation \| Maximum
Disclosure of defined benefit plans [line items]
Rate of return on investment	9.50	9.50	10.00	10.25
Actuarial discount rate of pension fund	9.50	9.50	9.50	9.50

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The expected rate of salary increases used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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No definition available.

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The decrease (increase) in the net defined benefit liability (asset) resulting from the gain (loss) on changes in the effect of limiting a net defined benefit asset to the asset ceiling, excluding amounts included in interest income or expense. [Refer: Interest income; Net defined benefit liability (asset); Interest expense (income), net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2019-01-01
-Paragraph 141
-Subparagraph c
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-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2019-en-r&anchor=para_141_c_iv&doctype=Standard
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The amount of other comprehensive income, net of tax, related to gains (losses) on remeasurements of defined benefit plans, which comprise actuarial gains and losses; the return on plan assets, excluding amounts included in net interest on the net defined benefit liability (asset); and any change in the effect of the asset ceiling, excluding amounts included in net interest on the net defined benefit liability (asset). [Refer: Other comprehensive income; Defined benefit plans [member]; Plan assets [member]; Net defined benefit liability (asset)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The discount rate of pension fund used as the significant actuarial assumption to determine the present value of a defined benefit obligation.

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The return on investments used as the significant actuarial assumption to determine the present value of a defined benefit obligation.

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- Definition

Amount of actuarial (loss)/gain arising from changes in experience.

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Amount of actuarial (loss)/gain arising from changes in financial assumptions.

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- Definition

Amount of past service cost expense recognized related to defined benefit plan.

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Amount of return on plan assets.

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Amount of interest expense recognized related to defined benefit plan.

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- Definition

The amount of post-employment benefit expense before charging to subsidiaries under contractual agreements relating to defined benefit plans.

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