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PROPERTY, PLANT, AND EQUIPMENT | 12 Months Ended
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Dec. 31, 2021
Property, Plant and Equipment [Abstract] |
PROPERTY, PLANT, AND EQUIPMENT | PROPERTY, PLANT, AND EQUIPMENTProperty, plant, and equipment is stated at original cost or fair value at acquisition, as appropriate, less any regulatory disallowances and impairments. Original cost may include: materials; labor; minor items of property; appropriate administrative and general costs; payroll-related costs such as taxes, pensions, and other benefits; and the interest capitalized and/or cost of equity funds used during construction. The Registrants' property, plant, and equipment in service consisted of the following at December 31, 2021 and 2020:
At December 31, 2021: | Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Power | Southern Company Gas
| (in millions)
Electric utilities: |  |  |  |  |  |
Generation | $ | 53,803 |  | $ | 16,631 |  | $ | 19,184 |  | $ | 2,791 |  | $ | 14,551 |  | $ | — |
Transmission | 13,406 |  | 5,334 |  | 7,132 |  | 900 |  | — |  | — |
Distribution | 22,236 |  | 8,643 |  | 12,437 |  | 1,156 |  | — |  | — |
General/other | 5,423 |  | 2,527 |  | 2,579 |  | 259 |  | 34 |  | — |
Electric utilities' plant in service | 94,868 |  | 33,135 |  | 41,332 |  | 5,106 |  | 14,585 |  | — |
Southern Company Gas: |  |  |  |  |  |
Natural gas distribution utilities transportation and distribution | 15,714 |  | — |  | — |  | — |  | — |  | 15,714 |
Storage facilities | 1,315 |  | — |  | — |  | — |  | — |  | 1,315 |
Other | 1,851 |  | — |  | — |  | — |  | — |  | 1,851 |
Southern Company Gas plant in service | 18,880 |  | — |  | — |  | — |  | — |  | 18,880 |
Other plant in service | 1,844 |  | — |  | — |  | — |  | — |  | — |
Total plant in service | $ | 115,592 |  | $ | 33,135 |  | $ | 41,332 |  | $ | 5,106 |  | $ | 14,585 |  | $ | 18,880 |
At December 31, 2020: | Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Power | Southern Company Gas
| (in millions)
Electric utilities: |  |  |  |  |  |
Generation | $ | 52,179 |  | $ | 16,201 |  | $ | 18,675 |  | $ | 2,819 |  | $ | 13,872 |  | $ | — |
Transmission | 12,879 |  | 5,033 |  | 6,951 |  | 856 |  | — |  | — |
Distribution | 20,958 |  | 8,248 |  | 11,622 |  | 1,088 |  | — |  | — |
General/other | 5,072 |  | 2,334 |  | 2,434 |  | 248 |  | 32 |  | — |
Electric utilities' plant in service | 91,088 |  | 31,816 |  | 39,682 |  | 5,011 |  | 13,904 |  | — |
Southern Company Gas: |  |  |  |  |  |
Natural gas distribution utilities transportation and distribution | 14,610 |  | — |  | — |  | — |  | — |  | 14,610 |
Storage facilities | 1,752 |  | — |  | — |  | — |  | — |  | 1,752 |
Other | 1,249 |  | — |  | — |  | — |  | — |  | 1,249 |
Southern Company Gas plant in service | 17,611 |  | — |  | — |  | — |  | — |  | 17,611 |
Other plant in service | 1,817 |  | — |  | — |  | — |  | — |  | — |
Total plant in service | $ | 110,516 |  | $ | 31,816 |  | $ | 39,682 |  | $ | 5,011 |  | $ | 13,904 |  | $ | 17,611 |
The cost of replacements of property, exclusive of minor items of property, is capitalized. The cost of maintenance, repairs, and replacement of minor items of property is charged to other operations and maintenance expenses as incurred or performed with the exception of nuclear refueling costs and certain maintenance costs including those described below. In accordance with orders from their respective state PSCs, Alabama Power and Georgia Power defer nuclear refueling outage operations and maintenance expenses to a regulatory asset when the charges are incurred. Alabama Power amortizes the costs over a subsequent 18-month period with Plant Farley's fall outage cost amortization beginning in January of the following year and spring outage cost amortization beginning in July of the same year. Georgia Power amortizes its costs over each unit's operating cycle, or 18 months for Plant Vogtle Units 1 and 2 and 24 months for Plant Hatch Units 1 and 2. Georgia Power's amortization period begins the month the refueling outage starts. A portion of Mississippi Power's railway track maintenance costs is charged to fuel stock and recovered through Mississippi Power's fuel clause. The portion of Southern Company Gas' non-working gas used to maintain the structural integrity of natural gas storage facilities that is considered to be non-recoverable is depreciated, while the recoverable or retained portion is not depreciated. See Note 9 for information on finance lease right-of-use (ROU) assets, net, which are included in property, plant, and equipment. The Registrants have deferred certain implementation costs related to cloud hosting arrangements. Once a hosted software is placed into service, the related deferred costs are amortized on a straight-line basis over the remaining expected hosting arrangement term, including any renewal options that are reasonably certain of exercise. The amortization is reflected with the associated cloud hosting fees, which are generally reflected in other operations and maintenance expenses on the Registrants' statements of income. At December 31, 2021 and 2020, deferred cloud implementation costs, which are generally included in other deferred charges and assets on the Registrants' balance sheets, are as follows:
| Southern Company | Alabama Power | Georgia Power | Mississippi Power | Southern Power | Southern Company Gas
| (in millions)
Deferred cloud implementation costs: |  |  |  |  |  |
At December 31, 2021 | $ | 240 |  | $ | 54 |  | $ | 81 |  | $ | 11 |  | $ | 14 |  | $ | 35 |
At December 31, 2020 | 162 |  | 38 |  | 58 |  | 7 |  | 9 |  | 17 |
Depreciation and Amortization The traditional electric operating companies' and Southern Company Gas' depreciation of the original cost of utility plant in service is provided primarily by using composite straight-line rates. The approximate rates for 2021, 2020, and 2019 are as follows:
| 2021 | 2020 | 2019
Alabama Power | 2.7 | % | 2.6 | % | 3.1 | %
Georgia Power | 3.3 | % | 3.0 | % | 2.6 | %
Mississippi Power | 3.6 | % | 3.7 | % | 3.7 | %
Southern Company Gas | 2.8 | % | 2.8 | % | 2.9 | %
Depreciation studies are conducted periodically to update the composite rates. These studies are filed with the respective state PSC and/or other applicable state and federal regulatory agencies for the traditional electric operating companies and the natural gas distribution utilities. During 2020, Georgia Power, Mississippi Power, and Atlanta Gas Light revised their depreciation rates in accordance with base rate case approvals by their respective PSCs. The revised rates were effective January 1, 2020 for Georgia Power and Atlanta Gas Light and April 1, 2020 for Mississippi Power. See Note 2 for additional information. When property, plant, and equipment subject to composite depreciation is retired or otherwise disposed of in the normal course of business, its original cost, together with the cost of removal, less salvage, is charged to accumulated depreciation. For other property dispositions, the applicable cost and accumulated depreciation are removed from the balance sheet accounts, and a gain or loss is recognized. Minor items of property included in the original cost of the asset are retired when the related property unit is retired. At December 31, 2021 and 2020, accumulated depreciation for Southern Company and Southern Company Gas consisted of utility plant in service totaling $33.1 billion and $31.6 billion, respectively, for Southern Company and $4.8 billion and $4.6 billion, respectively, for Southern Company Gas, as well as other plant in service totaling $930 million and $817 million, respectively, for Southern Company and $219 million and $195 million, respectively, for Southern Company Gas. Other plant in service includes the non-utility assets of Southern Company Gas, as well as, for Southern Company, certain other non-utility subsidiaries. Depreciation of the original cost of other plant in service is provided primarily on a straight-line basis over estimated useful lives. Useful lives for Southern Company Gas's non-utility assets range from five to 12 years for transportation equipment, 30 to 75 years for storage facilities, and up to 75 years for other assets. Useful lives for the assets of Southern Company's other non-utility subsidiaries range up to 37 years. Southern Power Southern Power applies component depreciation, where depreciation is computed principally by the straight-line method over the estimated useful life of the asset. Certain of Southern Power's generation assets related to natural gas-fired facilities are depreciated on a units-of-production basis, using hours or starts, to better match outage and maintenance costs to the usage of, and revenues from, these assets. The primary assets in Southern Power's property, plant, and equipment are generating facilities, which generally have estimated useful lives as follows:
Southern Power Generating Facility | Useful life
Natural gas | Up to 50 years
Solar | Up to 35 years
Wind | Up to 30 years
When Southern Power's depreciable property, plant, and equipment is retired, or otherwise disposed of in the normal course of business, the applicable cost and accumulated depreciation is removed and a gain or loss is recognized in the statements of income. Southern Power reviews its estimated useful lives and salvage values on an ongoing basis. The results of these reviews could result in changes which could have a material impact on Southern Power's net income. Joint Ownership Agreements At December 31, 2021, the Registrants' percentage ownership and investment (exclusive of nuclear fuel) in jointly-owned facilities in commercial operation were as follows:
Facility (Type) | Percent Ownership |  | Plant in Service |  | Accumulated Depreciation |  | CWIP
|  |  | (in millions)
Alabama Power |  |  |  |  |  |  |
Greene County (natural gas) Units 1 and 2 | 60.0 | % | (a) | $ | 191 |  |  | $ | 79 |  |  | $ | 1 |
Plant Miller (coal) Units 1 and 2 | 91.8 |  | (b) | 2,133 |  |  | 665 |  |  | 15 |
Georgia Power |  |  |  |  |  |  |
Plant Hatch (nuclear) | 50.1 | % | (c) | $ | 1,382 |  |  | $ | 647 |  |  | $ | 42 |
Plant Vogtle (nuclear) Units 1 and 2 | 45.7 |  | (c) | 3,611 |  |  | 2,265 |  |  | 86 |
Plant Scherer (coal) Units 1 and 2 | 8.4 |  | (c) | 276 |  |  | 100 |  |  | 1 |
Plant Scherer (coal) Unit 3 | 75.0 |  | (c) | 1,314 |  |  | 539 |  |  | 8 |
Plant Wansley (coal) | 53.5 |  | (c) | 1,070 |  |  | 472 |  |  | 7 |
Rocky Mountain (pumped storage) | 25.4 |  | (d) | 184 |  |  | 148 |  |  | 1 |
Mississippi Power |  |  |  |  |  |  |
Greene County (natural gas) Units 1 and 2 | 40.0 | % | (a) | $ | 124 |  |  | $ | 61 |  |  | $ | — |
Plant Daniel (coal) Units 1 and 2 | 50.0 |  | (e) | 762 |  |  | 237 |  |  | 19 |
Southern Company Gas |  |  |  |  |  |  |
Dalton Pipeline (natural gas pipeline) | 50.0 | % | (f) | $ | 271 |  |  | $ | 19 |  |  | $ | — |
(a)Jointly owned by Alabama Power and Mississippi Power and operated and maintained by Alabama Power. (b)Jointly owned with PowerSouth and operated and maintained by Alabama Power. (c)Georgia Power owns undivided interests in Plants Hatch, Vogtle Units 1 and 2, Scherer, and Wansley in varying amounts jointly with one or more of the following entities: OPC, MEAG Power, Dalton, Florida Power & Light Company, JEA, and Gulf Power. Georgia Power has been contracted to operate and maintain the plants as agent for the co-owners and is jointly and severally liable for third party claims related to these plants. (d)Jointly owned with OPC, which is the operator of the plant. (e)Jointly owned by Gulf Power and Mississippi Power. In accordance with the operating agreement, Mississippi Power acts as Gulf Power's agent with respect to the operation and maintenance of these units. See Note 3 under "Other Matters – Mississippi Power – Plant Daniel" for information regarding a commitment between Mississippi Power and Gulf Power to seek a restructuring of their 50% undivided ownership interests in Plant Daniel. (f)Jointly owned with The Williams Companies, Inc., the Dalton Pipeline is a 115-mile natural gas pipeline that serves as an extension of the Transcontinental Gas Pipe Line Company, LLC pipeline system into northwest Georgia. Southern Company Gas leases its 50% undivided ownership for approximately $26 million annually through 2042. The lessee is responsible for maintaining the pipeline during the lease term and for providing service to transportation customers under its FERC-regulated tariff. Georgia Power also owns 45.7% of Plant Vogtle Units 3 and 4, which are currently under construction and had a CWIP balance of $8.6 billion at December 31, 2021, excluding estimated probable losses recorded in 2018, 2020, and 2021. See Note 2 under "Georgia Power – Nuclear Construction" for additional information. The Registrants' proportionate share of their jointly-owned facility operating expenses is included in the corresponding operating expenses in the statements of income and each Registrant is responsible for providing its own financing. Assets Subject to Lien In 2018, the Mississippi PSC approved executed agreements between Mississippi Power and its largest retail customer, Chevron Products Company (Chevron), for Mississippi Power to continue providing retail service to the Chevron refinery in Pascagoula, Mississippi through at least 2038. The agreements grant Chevron a security interest in the co-generation assets owned by Mississippi Power, with a lease receivable balance of $167 million at December 31, 2021, located at the refinery that is exercisable upon the occurrence of (i) certain bankruptcy events or (ii) other events of default coupled with specific reductions in steam output at the facility and a downgrade of Mississippi Power's credit rating to below investment grade by two of the three rating agencies. See Note 8 under "Long-term Debt" for information regarding debt secured by certain assets of Georgia Power and Southern Company Gas.

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- Definition The entire disclosure for long-lived, physical asset used in normal conduct of business and not intended for resale. Includes, but is not limited to, work of art, historical treasure, and similar asset classified as collections. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 958 -SubTopic 360 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=120429125&loc=d3e99893-112916 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -URI http://asc.fasb.org/topic&trid=2155823 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 958 -SubTopic 360 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=120429125&loc=SL120174063-112916 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 958 -SubTopic 360 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=120429125&loc=d3e99779-112916 + Details
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