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REVENUES (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2022 | Mar. 31, 2021 | Dec. 31, 2021 | Sep. 01, 2021 | May 06, 2021
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | $ 3,452,000 | $ 2,771,700 |  |  |
Alternative Revenue Programs | 15,800 | 52,500 |  |  |
Other Revenues | 3,500 | 1,600 |  |  |
Operating Revenues | 3,471,310 | 2,825,840 |  |  |
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty | $ (58,412) | $ 30,000 |  |  |
Operating Lease, Income, Comprehensive Income [Extensible Enumeration] | Operating Revenues | Operating Revenues |  |  |
Lease revenue | $ 1,000 | $ 1,600 |  |  |
Unfavorable Regulatory Action |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Loss contingency, estimate of possible earnings impact, non-compliance with performance standards |  |  |  |  | $ 28,400
CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Operating Revenues | 1,285,831 | 987,274 |  |  |
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty | $ (58,412) | $ 30,000 |  |  |
Operating Lease, Income, Comprehensive Income [Extensible Enumeration] | Operating Revenues | Operating Revenues |  |  |
Lease revenue | $ 200 | $ 200 |  |  |
CL&P | Unfavorable Regulatory Action |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Loss contingency, estimate of possible earnings impact, non-compliance with performance standards |  |  |  | $ 28,400 |
CL&P | Unfavorable Regulatory Action | Sales |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
(Customer Credits)/Reserve at CL&P related to PURA Settlement Agreement and Storm Performance Penalty | 65,000 |  |  |  |
NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Operating Revenues | $ 863,176 | $ 737,043 |  |  |
Operating Lease, Income, Comprehensive Income [Extensible Enumeration] | Operating Revenues | Operating Revenues |  |  |
Lease revenue | $ 600 | $ 1,100 |  |  |
PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Operating Revenues | $ 339,427 | $ 293,435 |  |  |
Operating Lease, Income, Comprehensive Income [Extensible Enumeration] | Operating Revenues | Operating Revenues |  |  |
Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | $ 2,857,900 | $ 2,476,300 |  |  |
Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,771,200 | 1,560,000 |  |  |
Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 932,400 | 779,900 |  |  |
Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 154,300 | 136,400 |  |  |
Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 105,900 | 92,500 |  |  |
Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 399,800 | 176,300 |  |  |
Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 30,400 | 26,600 |  |  |
(Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 58,000 |  |  |  |
Operating Segments | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,430,100 | 1,102,700 |  |  |
Alternative Revenue Programs | 1,300 | 8,900 |  |  |
Other Revenues | 100 | 200 |  |  |
Operating Segments | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,004,700 | 838,500 |  |  |
Alternative Revenue Programs | (8,200) | 13,800 |  |  |
Other Revenues | 2,000 | 1,100 |  |  |
Operating Segments | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 395,100 | 333,700 |  |  |
Alternative Revenue Programs | (3,300) | 3,000 |  |  |
Other Revenues | 900 | 0 |  |  |
Operating Segments | Total Retail Tariff Sales Revenues | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 874,800 | 796,700 |  |  |
Operating Segments | Total Retail Tariff Sales Revenues | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 770,000 | 655,300 |  |  |
Operating Segments | Total Retail Tariff Sales Revenues | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 292,900 | 257,300 |  |  |
Operating Segments | Residential | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 599,100 | 545,800 |  |  |
Operating Segments | Residential | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 404,600 | 362,400 |  |  |
Operating Segments | Residential | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 182,500 | 157,800 |  |  |
Operating Segments | Commercial | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 242,200 | 214,200 |  |  |
Operating Segments | Commercial | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 331,300 | 268,300 |  |  |
Operating Segments | Commercial | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 88,400 | 77,800 |  |  |
Operating Segments | Industrial | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 33,500 | 36,700 |  |  |
Operating Segments | Industrial | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 34,100 | 24,600 |  |  |
Operating Segments | Industrial | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 22,000 | 21,700 |  |  |
Operating Segments | Wholesale Transmission Revenues | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 209,100 | 189,000 |  |  |
Operating Segments | Wholesale Transmission Revenues | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 165,200 | 147,100 |  |  |
Operating Segments | Wholesale Transmission Revenues | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 71,900 | 58,200 |  |  |
Operating Segments | Wholesale Market Sales Revenues | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 279,900 | 109,700 |  |  |
Operating Segments | Wholesale Market Sales Revenues | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 57,900 | 24,400 |  |  |
Operating Segments | Wholesale Market Sales Revenues | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 27,700 | 15,000 |  |  |
Operating Segments | Other Revenues from Contracts with Customers | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 7,900 | 7,300 |  |  |
Operating Segments | Other Revenues from Contracts with Customers | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 11,600 | 11,700 |  |  |
Operating Segments | Other Revenues from Contracts with Customers | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 2,600 | 3,200 |  |  |
Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 58,400 | 0 |  |  |
Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Operating Segments | Reserves For Revenues Subject To Refund | CL&P | Unfavorable Regulatory Action |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers |  |  | $ 93,400 |  |
Other |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 383,500 | 343,000 |  |  |
Alternative Revenue Programs | 0 | 0 |  |  |
Other Revenues | 0 | 0 |  |  |
Operating Revenues | 383,500 | 343,000 |  |  |
Other | Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Other | Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Other | Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Other | Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Other | Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 24,400 | 19,200 |  |  |
Other | Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Other | Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 359,100 | 323,800 |  |  |
Other | (Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 |  |  |  |
Eliminations |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | (723,400) | (647,200) |  |  |
Alternative Revenue Programs | 13,600 | 2,200 |  |  |
Other Revenues | 0 | 0 |  |  |
Operating Revenues | (709,800) | (645,000) |  |  |
Eliminations | Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | (5,600) | (4,900) |  |  |
Eliminations | Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Eliminations | Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | (1,100) | (1,400) |  |  |
Eliminations | Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | (4,500) | (3,500) |  |  |
Eliminations | Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | (364,700) | (321,000) |  |  |
Eliminations | Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Eliminations | Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | (353,100) | (321,300) |  |  |
Eliminations | (Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 |  |  |  |
Eliminations | CL&P |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Operating Revenues | (145,700) | (124,500) |  |  |
Eliminations | NSTAR Electric |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Operating Revenues | (135,300) | (116,400) |  |  |
Eliminations | PSNH |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Operating Revenues | (53,300) | (43,300) |  |  |
Electric Distribution | Operating Segments |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 2,378,700 | 1,876,200 |  |  |
Alternative Revenue Programs | 4,800 | 23,000 |  |  |
Other Revenues | 2,800 | 1,100 |  |  |
Operating Revenues | 2,386,300 | 1,900,300 |  |  |
Electric Distribution | Operating Segments | Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,937,100 | 1,708,900 |  |  |
Electric Distribution | Operating Segments | Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,186,200 | 1,066,000 |  |  |
Electric Distribution | Operating Segments | Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 661,300 | 559,900 |  |  |
Electric Distribution | Operating Segments | Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 89,600 | 83,000 |  |  |
Electric Distribution | Operating Segments | Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Electric Distribution | Operating Segments | Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 365,500 | 149,100 |  |  |
Electric Distribution | Operating Segments | Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 17,700 | 18,200 |  |  |
Electric Distribution | Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 58,400 |  |  |  |
Natural Gas Distribution | Operating Segments |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 917,000 | 757,500 |  |  |
Alternative Revenue Programs | 10,200 | 22,800 |  |  |
Other Revenues | 400 | 200 |  |  |
Operating Revenues | 927,600 | 780,500 |  |  |
Natural Gas Distribution | Operating Segments | Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 882,500 | 729,800 |  |  |
Natural Gas Distribution | Operating Segments | Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 556,800 | 466,300 |  |  |
Natural Gas Distribution | Operating Segments | Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 257,600 | 207,600 |  |  |
Natural Gas Distribution | Operating Segments | Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 68,100 | 55,900 |  |  |
Natural Gas Distribution | Operating Segments | Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Natural Gas Distribution | Operating Segments | Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 33,500 | 26,400 |  |  |
Natural Gas Distribution | Operating Segments | Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,000 | 1,300 |  |  |
Natural Gas Distribution | Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 |  |  |  |
Electric Transmission | Operating Segments |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 450,000 | 397,700 |  |  |
Alternative Revenue Programs | (15,000) | 2,700 |  |  |
Other Revenues | 200 | 200 |  |  |
Operating Revenues | 435,200 | 400,600 |  |  |
Electric Transmission | Operating Segments | Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Electric Transmission | Operating Segments | Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Electric Transmission | Operating Segments | Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Electric Transmission | Operating Segments | Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Electric Transmission | Operating Segments | Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 446,200 | 394,300 |  |  |
Electric Transmission | Operating Segments | Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Electric Transmission | Operating Segments | Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 3,800 | 3,400 |  |  |
Electric Transmission | Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 |  |  |  |
Water Distribution | Operating Segments |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 46,200 | 44,500 |  |  |
Alternative Revenue Programs | 2,200 | 1,800 |  |  |
Other Revenues | 100 | 100 |  |  |
Operating Revenues | 48,500 | 46,400 |  |  |
Water Distribution | Operating Segments | Total Retail Tariff Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 43,900 | 42,500 |  |  |
Water Distribution | Operating Segments | Residential |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 28,200 | 27,700 |  |  |
Water Distribution | Operating Segments | Commercial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 14,600 | 13,800 |  |  |
Water Distribution | Operating Segments | Industrial |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,100 | 1,000 |  |  |
Water Distribution | Operating Segments | Wholesale Transmission Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 0 | 0 |  |  |
Water Distribution | Operating Segments | Wholesale Market Sales Revenues |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 800 | 800 |  |  |
Water Distribution | Operating Segments | Other Revenues from Contracts with Customers |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | 1,900 | $ 1,200 |  |  |
Water Distribution | Operating Segments | (Reserve for)/Amortization of Revenues Subject to Refund |  |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |  |
Revenues from Contracts with Customers | $ (400) |  |  |  |

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- Definition Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
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