Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Commitments and Contingencies Disclosure [Abstract]

Estimated Minimum Purchases Under Fuel Contracts

The estimated minimum purchases for SPS under these contracts as of Dec. 31, 2015, are as follows:

(Millions of Dollars)	Coal		Natural gas supply		Natural gas storage and transportation
2016	$	242.0	$	9.6	$	31.5
2017	108.2		—		22.7
2018	—		—		20.8
2019	—		—		21.5
2020	—		—		21.5
Thereafter	—		—		74.4
Total	$	350.2	$	9.6	$	192.4

Estimated Future Payments for Capacity and Energy Pursuant to Purchased Power Agreements

At Dec. 31, 2015, the estimated future payments for capacity that SPS is obligated to purchase pursuant to these executory contracts, subject to availability, are as follows:

(Millions of Dollars)	Capacity
2016	$	56.8
2017	58.0
2018	57.0
2019	19.4
2020	11.8
Thereafter	42.6
Total	$	245.6

Future Commitments Under Operating Leases

Future commitments under operating leases are:

(Millions of Dollars)	Operating Leases		PPA (a) (b) Operating Leases		Total Operating Leases
2016	$	3.7	$	51.5	$	55.2
2017	4.5		48.5		53.0
2018	4.7		48.6		53.3
2019	4.7		48.6		53.3
2020	4.5		48.6		53.1
Thereafter	61.7		617.3		679.0

^(a)  Amounts do not include PPAs accounted for as executory contracts.

^(b)  PPA operating leases contractually expire through 2033.

Asset Retirement Obligations

A reconciliation of SPS’ AROs for the years ended Dec. 31, 2015 and 2014 is as follows:

(Thousands of Dollars)	Beginning Balance Jan. 1, 2015		Accretion		Cash Flow Revisions			Ending Balance     Dec. 31, 2015 (a)
Electric plant
Steam production asbestos	$	16,957	$	1,024	$	—		$	17,981
Steam production ash containment	1,609		85		(181		)	1,513
Electric distribution	6,327		232		—			6,559
Other	1,138		42		—			1,180
Total liability	$	26,031	$	1,383	$	(181	)	$	27,233

^(a)  There were no ARO liabilities recognized or settled during the year ended Dec. 31, 2015.

(Thousands of Dollars)	Beginning Balance Jan. 1, 2014		Liabilities Recognized		Accretion		Cash Flow     Revisions (a)		Ending Balance     Dec. 31, 2014 (b)
Electric plant
Steam production asbestos	$	11,608	$	—	$	795	$	4,554	$	16,957
Steam production ash containment	809		—		51		749		1,609
Electric distribution	6,104		—		223		—		6,327
Other	854		136		31		117		1,138
Total liability	$	19,375	$	136	$	1,100	$	5,420	$	26,031

^(a)  In 2014, revisions were made to various AROs due to revised estimated cash flows and the timing of those cash flows. Changes in the asbestos AROs were related to updated costs from the 2014 dismantling study.

^(b)  There were no ARO liabilities settled during the year ended Dec. 31, 2014.