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Lease Commitments (Details) - Public Service Company of New Mexico [Member] $ in Millions | 3 Months Ended |
--- | --- | ---
Mar. 31, 2016 USD ($) MW | Mar. 31, 2015 | Apr. 01, 2015 USD ($)
Operating Leased Assets [Line Items] |  |  |
Ownership of the EIP |  | 60.00% |
Percent leased, now expired |  |  | 40.00%
Leased capacity at fair market value, elected to purchase |  |  | $ 7.7
Palo Verde Nuclear Generating Station, Unit 2 Leases 31.2494 MW [Member] |  |  |
Operating Leased Assets [Line Items] |  |  |
Payment to lessors | $ 78.1 |  |
Palo Verde Nuclear Generating Station, Unit 2 Leases [Member] |  |  |
Operating Leased Assets [Line Items] |  |  |
Leased capacity to be purchased (in megawatts) | MW | 32.76 |  |
Palo Verde Nuclear Generating Station, Unit 2 Leases, January 15, 2016 [Member] |  |  |
Operating Leased Assets [Line Items] |  |  |
Leased capacity to be purchased (in megawatts) | MW | 31.25 |  |
Palo Verde Nuclear Generating Station, Unit 2 Leases 32.76 MW [Member] |  |  |
Operating Leased Assets [Line Items] |  |  |
Payment to lessors | $ 85.2 |  |
Palo Verde Nuclear Generating Station [Member] |  |  |
Operating Leased Assets [Line Items] |  |  |
Loss contingency, lease arrangements | $ 179.1 |  |

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