SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Future Expected Operating Lease Payments and Expected Obligations for Power Purchase and Other Lease Commitments) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Future Expected Operating Lease Payments
2020	$ 679
2021	623
2022	548
2023	255
2024	96
Thereafter	596
Total lease payments	2,797
Less imputed interest	(518)
Total	$ 2,279
Future Expected Obligations and Other Commitments
2020		$ 684
2021		677
2022		621
2023		546
2024		252
Thereafter		581
Total minimum lease payments		$ 3,361

Amount of lessee's undiscounted obligation for lease payments for operating lease.

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Amount of lessee's undiscounted obligation for lease payments for operating lease having an initial or remaining lease term in excess of one year due in remainder of fiscal year following latest fiscal year.

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