Nuclear Obligations (Tables)

12 Months Ended

Dec. 31, 2015

Nuclear Obligations [Abstract]

Funded Status of Nuclear Decommissioning Obligation

As of Dec. 31, 2015, NSP-Minnesota has accumulated $1.7 billion of assets held in external decommissioning trusts. The following table summarizes the funded status of NSP-Minnesota’s decommissioning obligation based on parameters established in the most recently approved decommissioning study. Xcel Energy believes future decommissioning costs, if necessary, will continue to be recovered in customer rates. The amounts presented below were prepared on a regulatory basis, and are not recorded in the financial statements for the ARO.

	Regulatory Basis
(Thousands of Dollars)	2015			2014
Estimated decommissioning cost obligation from most recently approved study (in 2014 and 2011 dollars, respectively)	$	3,012,342		$	2,694,079
Effect of escalating costs (to 2015 and 2014 dollars, respectively, at 4.36/3.36 percent and 3.63/2.63 percent, respectively)	126,464			289,907
Estimated decommissioning cost obligation (in current dollars)	3,138,806			2,983,986
Effect of escalating costs to payment date (4.36/3.36 percent and 3.63/2.63 percent, respectively)	8,066,688			5,597,302
Estimated future decommissioning costs (undiscounted)	11,205,494			8,581,288
Effect of discounting obligation (using average risk-free interest rate of 3.01 percent and 2.82 percent for 2015 and 2014, respectively)	(6,891,392		)	(5,044,470		)
Discounted decommissioning cost obligation	$	4,314,102		$	3,536,818
Assets held in external decommissioning trust	$	1,724,150		$	1,703,921
Underfunding of external decommissioning fund compared to the discounted decommissioning obligation	2,589,952			1,832,897

Reconciliation of Decommissioning Cost Obligation - Regulatory to GAAP

Calculations and data used by the regulator in approving company rates are useful in assessing future cash flows. The regulatory basis information is a means to reconcile amounts previously provided to the MPUC and utilized for regulatory purposes to amounts used for financial reporting. The following table provides a reconciliation of the discounted decommissioning cost obligation - regulated basis to the ARO recorded in accordance with GAAP:

(Thousands of Dollars)	2015			2014
Discounted decommissioning cost obligation - regulated basis	$	4,314,102		$	3,536,818
Differences in discount rate and market risk premium	(1,275,438		)	(1,275,101		)
Operating and maintenance costs not included for GAAP	(897,640		)	(547,135		)
Differences in cost studies (2011 versus 2014, no change in 2015)	—			323,365
Nuclear production decommissioning ARO - GAAP	$	2,141,024		$	2,037,947

Nuclear Decommissioning Expenses Recognized as Result of Regulation

Decommissioning expenses recognized as a result of regulation for the years ending Dec. 31 were:

(Thousands of Dollars)	2015		2014		2013
Annual decommissioning recorded as depreciation expense: (a)	$	6,862	$	7,138	$	6,402

^(a)  Decommissioning expense does not include depreciation of the capitalized nuclear asset retirement costs.