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Description of Business - Electric & Gas Utilities - United States (Details) km in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2016 station county km MW | Oct. 31, 2016 | Oct. 14, 2016 station
ITC |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Peak transmission line capacity (MW) (more than) | 26,000 |  |
Area of operation (km) | km | 25 |  |
Number of third-party generating stations with transmission assets | station | 570 |  | 570
TEP and UNS Electric, Inc |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Generating capacity (MW) | 2,994 |  |
TEP and UNS Electric, Inc | Solar |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Generating capacity (MW) | 54 |  |
TEP and UNS Electric, Inc | Coal |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Generating Capacity, Percent | 47.00% |  |
Central Hudson |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Number of countries in which entity operates | county | 8 |  |
Central Hudson | Gas-Fired and Hydroelectric Power Generation |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Generating capacity (MW) | 64 |  |
ITC |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Controlling ownership interest (percent) |  | 80.10% | 80.10%
Noncontrolling ownership (percent) |  | 19.90% | 19.90%

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