Lease Commitments (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 Public Service Company of New Mexico [Member]	Jun. 30, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station [Member]	Feb. 25, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station, Unit 2 Leases 31.2494 MW [Member]	May 01, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station, Unit 2 Leases [Member] MW	Jun. 30, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station, Unit 2 Leases, January 15, 2016 [Member] MW	May 01, 2014 Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station, Unit 2 Leases 32.76 MW [Member]	May 01, 2014 Maximum [Member] Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station, Unit 2 Leases 32.76 MW [Member]	May 01, 2014 Minimum [Member] Public Service Company of New Mexico [Member] Palo Verde Nuclear Generating Station, Unit 2 Leases 32.76 MW [Member]
Operating Leased Assets [Line Items]
Rental Payments, Fixed renewal option period during original terms of leases			50.00%
Purchase Price of Leased Asset to be paid January 15, 2016				$ 78.1			$ 85.2
Leased Capacity to be Purchased					32.76	31.2494
Early Purchase Price of Leased Asset effective June 1, 2014							79.9
Additional consideration for early purchase of leased asset effective June 1, 2014								$ 5.8	$ 1.2
Operating Lease, Extended Term	2 years
Operating Leases, Renewal Options After Original Lease Term (in years)	6 years	2 years