Northern States Power 10-Q 28 Apr 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 28, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	NORTHERN STATES POWER CO /WI/
Entity Central Index Key	72,909
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		933,000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating revenues
Electric	$ 216,309	$ 211,524
Natural gas	48,347	43,020
Other	275	306
Total operating revenues	264,931	254,850
Operating expenses
Electric fuel and purchased power, non-affiliates	2,873	3,981
Purchased power, affiliates	106,458	108,714
Cost of natural gas sold and transported	25,987	23,418
Operating and maintenance expenses	49,862	48,619
Conservation program expenses	3,054	3,066
Depreciation and amortization	27,049	24,449
Taxes (other than income taxes)	6,873	7,155
Total operating expenses	222,156	219,402
Operating income	42,775	35,448
Other income, net	246	449
Allowance for funds used during construction — equity	1,287	810
Interest charges and financing costs
Interest charges — includes other financing costs of $456 and $462, respectively	8,682	8,604
Allowance for funds used during construction — debt	(550)	(347)
Total interest charges and financing costs	8,132	8,257
Income before income taxes	36,176	28,450
Income taxes	13,757	10,819
Net income	$ 22,419	$ 17,631

CONSOLIDATED STATEMENTS OF INC3

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Interest charges and financing costs
Other financing costs	$ 456	$ 462

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Comprehensive income:
Net income	$ 22,419	$ 17,631
Derivative instruments:
Reclassification of losses to net income, net of tax of $12 and $13, respectively	19	19
Other comprehensive income	19	19
Comprehensive income	$ 22,438	$ 17,650

CONSOLIDATED STATEMENTS OF COM5

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative instruments:
Reclassification of losses to net income, net of tax	$ 12	$ 13

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating activities
Net income	$ 22,419	$ 17,631
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	27,425	24,829
Deferred income taxes	11,348	5,284
Amortization of investment tax credits	(131)	(132)
Allowance for equity funds used during construction	(1,287)	(810)
Net derivative losses	166	200
Changes in operating assets and liabilities:
Accounts receivable	(10,867)	(2,797)
Accrued unbilled revenues	12,986	7,326
Inventories	4,806	6,717
Other current assets	4,305	6,348
Accounts payable	19,809	2,325
Net regulatory assets and liabilities	656	1,856
Other current liabilities	(9,158)	3,492
Pension and other employee benefit obligations	(8,860)	(7,264)
Change in other noncurrent assets	(294)	(319)
Change in other noncurrent liabilities	(800)	798
Net cash provided by operating activities	72,523	65,484
Investing activities
Utility capital/construction expenditures	(47,999)	(44,655)
Allowance for equity funds used during construction	1,287	810
Other, net	(159)	292
Net cash used in investing activities	(46,871)	(43,553)
Financing activities
Repayments of short-term borrowings, net	(27,000)	(5,000)
Repayments of long-term debt	(13)	(14)
Capital contributions from (to) parent	12,282	(1,545)
Dividends paid to parent	(10,729)	(15,322)
Other, net	(70)	0
Net cash used in financing activities	(25,530)	(21,881)
Net change in cash and cash equivalents	122	50
Cash and cash equivalents at beginning of period	1,546	1,079
Cash and cash equivalents at end of period	1,668	1,129
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(6,020)	(6,305)
Cash paid for income taxes, net	(11,489)	(2,424)
Supplemental disclosure of non-cash investing transactions:
Property, plant and equipment additions in accounts payable	$ 15,150	$ 9,586

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents	$ 1,668	$ 1,546
Accounts receivable, net	64,898	54,031
Accrued unbilled revenues	40,652	53,638
Inventories	13,503	18,309
Regulatory assets	18,126	18,162
Prepaid taxes	20,414	25,915
Prepayments and other	4,831	3,785
Total current assets	164,092	175,386
Property, plant and equipment, net	1,972,130	1,947,637
Other assets
Regulatory assets	284,587	286,188
Other investments	3,003	2,844
Other	1,079	785
Total other assets	288,669	289,817
Total assets	2,424,891	2,412,840
Current liabilities
Current portion of long-term debt	1,110	1,123
Short-term debt	33,000	60,000
Notes payable to affiliates	500	500
Accounts payable	31,886	41,068
Accounts payable to affiliates	55,082	29,037
Dividends payable to parent	13,071	10,729
Regulatory liabilities	20,830	17,428
Environmental liabilities	40,413	41,438
Accrued interest	9,681	8,012
Other	15,128	26,484
Total current liabilities	220,701	235,819
Deferred credits and other liabilities
Deferred income taxes	442,771	430,593
Deferred investment tax credits	7,906	8,037
Regulatory liabilities	149,713	148,189
Environmental liabilities	21,827	23,003
Customer advances	18,780	19,425
Pension and employee benefit obligations	46,157	55,164
Other	18,695	18,814
Total deferred credits and other liabilities	705,849	703,225
Commitments and contingencies
Capitalization
Long-term debt	662,125	661,946
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at March 31, 2017 and Dec. 31, 2016, respectively	93,300	93,300
Additional paid in capital	410,315	395,315
Retained earnings	332,715	323,368
Accumulated other comprehensive loss	(114)	(133)
Total common stockholder’s equity	836,216	811,850
Total liabilities and equity	$ 2,424,891	$ 2,412,840

CONSOLIDATED BALANCE SHEETS (U8

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) - $ / shares	Mar. 31, 2017	Dec. 31, 2016
Capitalization
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares outstanding (in shares)	933,000	933,000

Management's Opinion

Management's Opinion	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Management's Opinion	In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with accounting principles generally accepted in the United States of America (GAAP), the financial position of NSP-Wisconsin and its subsidiaries as of March 31, 2017 and Dec. 31, 2016 ; the results of its operations, including the components of net income and comprehensive income, for the three months ended March 31, 2017 and 2016; and its cash flows for the three months ended March 31, 2017 and 2016. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2017 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2016 balance sheet information has been derived from the audited 2016 consolidated financial statements included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2016 . These notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto, included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2016 , filed with the SEC on Feb. 24, 2017. Due to the seasonality of NSP-Wisconsin’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The significant accounting policies set forth in Note 1 to the consolidated financial statements in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2016, appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

Accounting Pronouncements

Accounting Pronouncements	3 Months Ended
	Mar. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Accounting Pronouncements	Accounting Pronouncements Recently Issued Revenue Recognition — In May 2014, the Financial Accounting Standards Board (FASB) issued Revenue from Contracts with Customers, Topic 606 (Accounting Standards Update (ASU) No. 2014-09) , which provides a new framework for the recognition of revenue. NSP-Wisconsin expects its adoption will result in increased disclosures regarding revenue, cash flows and obligations related to arrangements with customers, as well as separate presentation of alternative revenue programs. NSP-Wisconsin has not yet fully determined the impacts of adoption for several aspects of the standard, including a determination whether and how much an evaluation of the collectability of regulated electric and gas revenues will impact the amounts of revenue recognized upon delivery. NSP-Wisconsin currently expects to implement the standard on a modified retrospective basis, which requires application to contracts with customers effective Jan. 1, 2018, with the cumulative impact on contracts not yet completed as of Dec. 31, 2017 recognized as an adjustment to the opening balance of retained earnings. Classification and Measurement of Financial Instruments — In January 2016, the FASB issued Recognition and Measurement of Financial Assets and Financial Liabilities, Subtopic 825-10 (ASU No. 2016-01) , which eliminates the available-for-sale classification for marketable equity securities, and also replaces the cost method of accounting for non-marketable equity securities with a model for recognizing impairments and observable price changes. Under the new standard, other than when the consolidation or equity method of accounting is utilized, changes in the fair value of equity securities are to be recognized in earnings. This guidance will be effective for interim and annual reporting periods beginning after Dec. 15, 2017. NSP-Wisconsin expects that the overall impacts of the Jan. 1, 2018 adoption will not be material. Leases — I n February 2016, the FASB issued Leases, Topic 842 (ASU No. 2016-02) , which for lessees requires balance sheet recognition of right-of-use assets and lease liabilities for most leases. This guidance will be effective for interim and annual reporting periods beginning after Dec. 15, 2018. NSP-Wisconsin has not yet fully determined the impacts of implementation. However, adoption is expected to occur on Jan. 1, 2019 utilizing the practical expedients provided by the standard. As such, agreements entered prior to Jan. 1, 2017 that are currently considered leases are expected to be recognized on the consolidated balance sheet, including contracts for use of office space, equipment and natural gas storage assets, as well as certain purchased power agreements (PPAs) for natural gas-fueled generating facilities. NSP-Wisconsin expects that similar agreements entered after Dec. 31, 2016 will generally qualify as leases under the new standard, but has not yet completed its evaluation of certain other contracts, including arrangements for the secondary use of assets, such as land easements. Presentation of Net Periodic Benefit Cost — I n March 2017, the FASB issued Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, Topic 715 (ASU No. 2017-07) , which establishes that only the service cost element of pension cost may be presented as a component of operating income in the income statement. Also under the guidance, only the service cost component of pension cost is eligible for capitalization. NSP-Wisconsin has not yet fully determined the impacts of adoption of the standard, but expects that as a result of application of accounting principles for rate regulated entities, a similar amount of pension cost, including non-service components, will be recognized consistent with the current ratemaking treatment, and that the impacts of adoption will be limited to changes in classification of non-service costs in the consolidated statement of income. This guidance will be effective for interim and annual reporting periods beginning after Dec. 15, 2017.

Selected Balance Sheet Data

Selected Balance Sheet Data	3 Months Ended
	Mar. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Selected Balance Sheet Data	Selected Balance Sheet Data (Thousands of Dollars) March 31, 2017 Dec. 31, 2016 Accounts receivable, net (a) Accounts receivable $ 69,975 $ 58,896 Less allowance for bad debts (5,077 ) (4,865 ) $ 64,898 $ 54,031 (a) Accounts receivable, net includes an immaterial amount due from affiliates as of March 31, 2017 and Dec. 31, 2016, respectively. (Thousands of Dollars) March 31, 2017 Dec. 31, 2016 Inventories Materials and supplies $ 6,798 $ 6,582 Fuel 4,893 4,743 Natural gas 1,812 6,984 $ 13,503 $ 18,309 (Thousands of Dollars) March 31, 2017 Dec. 31, 2016 Property, plant and equipment, net Electric plant $ 2,520,158 $ 2,499,401 Natural gas plant 299,926 294,986 Common and other property 156,213 156,316 Construction work in progress 135,927 118,822 Total property, plant and equipment 3,112,224 3,069,525 Less accumulated depreciation (1,140,094 ) (1,121,888 ) $ 1,972,130 $ 1,947,637

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Except to the extent noted below, Note 6 to the consolidated financial statements included in NSP-Wisconsin’s Annual Report on Form 10-K for the year ended Dec. 31, 2016 appropriately represents, in all material respects, the current status of other income tax matters, and are incorporated herein by reference. Federal Audit — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files a consolidated federal income tax return. In 2012, the Internal Revenue Service (IRS) commenced an examination of tax years 2010 and 2011 , including the 2009 carryback claim. As of March 31, 2017, the IRS had proposed an adjustment to the federal tax loss carryback claims that would result in $14 million of income tax expense for the 2009 through 2011 claims, and the 2013 through 2015 claims. In the fourth quarter of 2015, the IRS forwarded the issue to the Office of Appeals (Appeals). In 2016 the IRS audit team and Xcel Energy presented their case to Appeals; however, the outcome and timing of a resolution is uncertain. The statute of limitations applicable to Xcel Energy’s 2009 through 2011 federal income tax returns, following extensions, expires in December 2017. Xcel Energy has recognized its best estimate of income tax expense that will result from a final resolution of the IRS's proposed adjustment of the carryback claims. NSP-Wisconsin is not expected to accrue any income tax expense related to this adjustment. In the third quarter of 2015, the IRS commenced an examination of tax years 2012 and 2013 . In the first quarter of 2017, the IRS proposed an adjustment to tax years 2012 and 2013 that could have impacted Xcel Energy’s net operating loss (NOL) and tax credit carryforwards and effective tax rate (ETR). After additional review, the IRS withdrew their proposed adjustment. As of March 31, 2017, the IRS had not proposed any other material adjustments to tax years 2012 and 2013. State Audits — NSP-Wisconsin is a member of the Xcel Energy affiliated group that files consolidated state income tax returns. As of March 31, 2017, NSP-Wisconsin’s earliest open tax year that is subject to examination by state taxing authorities under applicable statutes of limitations is 2012 . In 2016, Wisconsin began an audit of years 2012 and 2013 . As of March 31, 2017, Wisconsin had not proposed any adjustments, and there were no other state income tax audits in progress. Unrecognized Tax Benefits — The unrecognized tax benefit balance includes permanent tax positions, which if recognized would affect the annual ETR. In addition, the unrecognized tax benefit balance includes temporary tax positions for which the ultimate deductibility is highly certain but for which there is uncertainty about the timing of such deductibility. A change in the period of deductibility would not affect the ETR but would impact the timing of cash payment to the taxing authority. A reconciliation of the amount of unrecognized tax benefit is as follows: (Millions of Dollars) March 31, 2017 Dec. 31, 2016 Unrecognized tax benefit — Permanent tax positions $ 0.4 $ 0.4 Unrecognized tax benefit — Temporary tax positions 5.0 4.9 Total unrecognized tax benefit $ 5.4 $ 5.3 The unrecognized tax benefit amounts were reduced by the tax benefits associated with NOL and tax credit carryforwards. The amounts of tax benefits associated with NOL and tax credit carryforwards are as follows: (Millions of Dollars) March 31, 2017 Dec. 31, 2016 NOL and tax credit carryforwards $ (1.2 ) $ (1.2 ) It is reasonably possible that NSP-Wisconsin’s amount of unrecognized tax benefits could significantly change in the next 12 months as the IRS Appeals and audit progress, the Wisconsin audit progresses, and other state audits resume. As the IRS Appeals and IRS and Wisconsin audits progress, it is reasonably possible that the amount of unrecognized tax benefit could decrease up to approximately $2 million . The payable for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards. The payables for interest related to unrecognized tax benefits at March 31, 2017 and Dec. 31, 2016 were not material. No amounts were accrued for penalties related to unrecognized tax benefits as of March 31, 2017 or Dec. 31, 2016.

Rate Matters Rate Matters (Note

Rate Matters Rate Matters (Notes)	3 Months Ended
	Mar. 31, 2017
Public Utilities, General Disclosures [Abstract]
Rate Matters	Rate Matters Except to the extent noted below, the circumstances set forth in Note 10 to the consolidated financial statements included in NSP-Wisconsin’s Annual Report on Form 10-K for the year ended Dec. 31, 2016, appropriately represent, in all material respects, the current status of other rate matters, and are incorporated herein by reference. Recently Concluded Regulatory Proceedings - Michigan Public Service Commission (MPSC) Michigan 2017 Natural Gas Rate Case — In October 2016, NSP-Wisconsin filed a request with the MPSC to increase base rates for natural gas service by approximately $347 thousand annually, or 6.5 percent . The filing was based on a 2017 forecast test year, a 10.2 percent return on equity (ROE), an equity ratio of 52.56 percent and a forecasted average rate base of approximately $6.4 million . The primary driver of the requested increase is investment in natural gas distribution infrastructure, mainly in conjunction with the NSP-Wisconsin’s Distribution Integrity Management Program (DIMP). NSP-Wisconsin also proposed an Infrastructure Cost Recovery Mechanism (ICRM) rate rider to recover ongoing costs associated with the DIMP. In addition, the filing requested recovery of approximately $129 thousand , or 2.4 percent , through the ICRM, beginning in January 2018. Under the proposal, the ICRM rider would be adjusted annually. No party sought to intervene in the case. In March 2017, NSP-Wisconsin reached a settlement with the MPSC staff that eliminated the ICRM rider in lieu of a multi-year rate plan that includes funding for the DIMP. The settlement authorized a $266 thousand , or 5 percent overall rate increase for 2017, followed by a $140 thousand , or 2.5 percent step increase in January 2018, and another $143 thousand , or 2.5 percent step increase in January 2019. The settlement was based on a 10.0 percent ROE and a 52.56 percent equity ratio. On March 28, 2017 the MPSC issued an order approving the settlement agreement and new rates went into effect on April 1, 2017. Pending Regulatory Proceeding — Federal Energy Regulatory Commission (FERC) Midcontinent Independent System Operator, Inc. (MISO) ROE Complaints/ROE Adder — In November 2013, a group of customers filed a complaint at the FERC against MISO transmission owners (TOs), including NSP-Minnesota and NSP-Wisconsin. The complaint argued for a reduction in the ROE in transmission formula rates in the MISO region from 12.38 percent to 9.15 percent , a prohibition on capital structures in excess of 50 percent equity, and the removal of ROE adders (including those for Regional Transmission Organization (RTO) membership and for being an independent transmission company), effective Nov. 12, 2013. In December 2015, an Administrative Law Judge (ALJ) recommended the FERC approve a ROE of 10.32 percent using a FERC ROE methodology adopted in June 2014, which the FERC upheld in an order issued in September 2016. This ROE is applicable for the 15 month refund period from Nov. 12, 2013 to Feb. 11, 2015, and prospectively from the date of the FERC order. The total prospective ROE is 10.82 percent , which includes a 50 basis point adder for RTO membership. In February 2015, a second complaint seeking to reduce the MISO ROE from 12.38 percent to 8.67 percent prior to any adder was filed with the FERC, resulting in a second period of potential refund from Feb. 12, 2015 to May 11, 2016. The MPUC, the North Dakota Public Service Commission, the South Dakota Public Utilities Commission and the Minnesota Department of Commerce joined a joint complainant/intervenor initial brief recommending an ROE of approximately 8.81 percent . FERC staff recommended a ROE of 8.78 percent . The MISO TOs recommended a ROE of 10.92 percent . In June 2016, the ALJ recommended a ROE of 9.7 percent , the midpoint of the upper half of the discounted cash flow (DCF) range, applying the June 2014 FERC ROE methodology. A decision was expected later in 2017, but could be delayed by the lack of a quorum at the FERC. On April 14, 2017 the D.C. Circuit Court of Appeals vacated and remanded the June 2014 FERC decision, previously made in a New England ROE case. The court decision found that the FERC in that case had not established that the prior ROE was unjust and unreasonable, and that the FERC also failed to adequately support the newly approved ROE. The New England ROE ruling was then the basis for the ROE methodology used in the MISO complaint cases. The court found that the ROE methodology used in the New England ROE case was inadequate because it relied on approaches other than the DCF model. The impact of this court decision on the pending MISO complaint cases is uncertain. As of March 2017, NSP-Minnesota has recognized a current liability for the Nov. 12, 2013 to Feb. 11, 2015 complaint period based on the 10.32 percent ROE provided in the FERC order. This liability is net of refunds processed during the first quarter of 2017. NSP-Minnesota has also recognized a current liability representing the best estimate of the final ROE for the Feb. 12, 2015 to May 11, 2016 complaint period.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Except to the extent noted below and in Note 5 above, the circumstances set forth in Notes 10 and 11 to the consolidated financial statements included in NSP-Wisconsin’s Annual Report on Form 10-K for the year ended Dec. 31, 2016 , appropriately represent, in all material respects, the current status of commitments and contingent liabilities, and are incorporated herein by reference. The following include commitments, contingencies and unresolved contingencies that are material to NSP-Wisconsin’s financial position. Guarantees NSP-Wisconsin provides a guarantee for payment of customer loans related to NSP-Wisconsin’s farm rewiring program. NSP-Wisconsin’s exposure under the guarantee is based upon the net liability under the agreement. The guarantee issued by NSP-Wisconsin has a stated maximum amount. The guarantee contains no recourse provisions and requires no collateral. These agreements have expiration dates through 2020 . The following table presents the guarantee issued and outstanding for NSP-Wisconsin: (Millions of Dollars) March 31, 2017 Dec. 31, 2016 Guarantee issued and outstanding $ 1.0 $ 1.0 Current exposure under this guarantee 0.1 0.1 Environmental Contingencies Ashland Manufactured Gas Plant (MGP) Site — NSP-Wisconsin has been named a potentially responsible party (PRP) for contamination at a site in Ashland, Wis. The Ashland/Northern States Power Lakefront Superfund Site (the Site) includes NSP-Wisconsin property, previously operated as a MGP facility (the Upper Bluff), and two other properties: an adjacent city lakeshore park area (Kreher Park); and an area of Lake Superior’s Chequamegon Bay adjoining the park. In 2012, NSP-Wisconsin agreed to remediate the Phase I Project Area (which includes the Upper Bluff and Kreher Park areas of the Site), under a settlement agreement with the United States Environmental Protection Agency (EPA), The current cost estimate for the cleanup of the Phase I Project Area is approximately $77.2 million , of which approximately $57.2 million has been spent. NSP-Wisconsin performed a wet dredge pilot study in 2016 and demonstrated that a wet dredge remedy can meet the performance standards for remediation of the Sediments. As a result, the EPA authorized NSP-Wisconsin to extend the wet dredge pilot to additional areas of the Site. In January 2017, NSP-Wisconsin agreed to remediate the Phase II Project Area (the Sediments), under a settlement agreement with the EPA. The settlement was approved by the U.S. District Court for the Western District of Wisconsin NSP-Wisconsin has initiated field activities to perform a full scale wet dredge remedy of the Sediments in 2017, with performance of restoration activities in 2018. At March 31, 2017 and Dec. 31, 2016, NSP-Wisconsin had recorded a total liability of $62.1 million and $64.3 million , respectively, for the entire site. NSP-Wisconsin has deferred the unrecovered portion of the estimated Site remediation costs as a regulatory asset. The Public Service Commission of Wisconsin (PSCW) has consistently authorized NSP-Wisconsin rate recovery for all remediation costs incurred at the Site. In 2012, the PSCW agreed to allow NSP-Wisconsin to pre-collect certain costs, to amortize costs over a ten -year period and to apply a three percent carrying cost to the unamortized regulatory asset. In April 2016, NSP-Wisconsin filed a limited natural gas rate case for recovery of additional expenses associated with remediating the Site. In December 2016, the PSCW issued a written order approving the requested increase in annual recovery of MGP clean-up costs from $7.6 million in 2016 to $12.4 million in 2017. Other MGP Sites — In addition to the site in Ashland, Wis., NSP-Wisconsin has identified one site where former MGP disposal activities may have resulted in site contamination and is under current investigation. There are other parties that may have responsibility for some portion of any remediation. NSP-Wisconsin anticipates that the majority of the investigation or remediation at this site will continue through at least 2018. NSP-Wisconsin had accrued $0.1 million for this site at March 31, 2017 and Dec. 31, 2016. There may be insurance recovery and/or recovery from other PRPs to offset any costs incurred. NSP-Wisconsin anticipates that any significant amounts incurred will be recovered from customers. Environmental Requirements Water and Waste Federal Clean Water Act (CWA) Waters of the United States Rule — In 2015, the EPA and the U.S. Army Corps of Engineers (Corps) published a final rule that significantly expands the types of water bodies regulated under the CWA and broadens the scope of waters subject to federal jurisdiction. The final rule will subject more utility projects to federal CWA jurisdiction, thereby potentially delaying the siting of new generation projects, pipelines, transmission lines and distribution lines, as well as increasing project costs and expanding permitting and reporting requirements. In October 2015, the U.S. Court of Appeals for the Sixth Circuit issued a nationwide stay of the final rule and subsequently ruled that it, rather than the federal district courts, had jurisdiction over challenges to the rule. In January 2017, the U.S. Supreme Court agreed to resolve the dispute as to which court should hear challenges to the rule. A ruling is expected by the end of 2017. In February 2017, President Trump issued an executive order requiring the EPA and the Corps to review and revise the final rule. The executive order directs the agencies to consider interpreting the term “Waters of the U.S.” in a manner that is more narrow than the final rule. In March 2017, the EPA and the Corps published formal notice of the agencies’ intent to review the final rule and engage in further rulemaking. Federal CWA Effluent Limitations Guidelines (ELG) — In 2015, the EPA issued a final ELG rule for power plants that use coal, natural gas, oil or nuclear materials as fuel and discharge treated effluent to surface waters as well as utility-owned landfills that receive coal combustion residuals. NSP-Wisconsin continues to evaluate the cost of compliance at its facilities potentially affected by this rule. NSP-Wisconsin believes that compliance costs would be recoverable through regulatory mechanisms. Consolidated challenges to the rule are being heard by the Fifth Circuit Court of Appeals. On April 12, 2017, the EPA issued an administrative stay to delay the ELG rule’s compliance deadlines during the pendency of the ongoing litigation in order to give the agency the opportunity to reconsider and review the rule. Air Greenhouse Gas (GHG) Emission Standard for Existing Sources (Clean Power Plan or CPP) — In 2015, the EPA issued its final rule for existing power plants. Among other things, the rule requires that state plans include enforceable measures to ensure emissions from existing power plants achieve the EPA’s state-specific interim (2022-2029) and final (2030 and thereafter) emission performance targets. The CPP was challenged by multiple parties in the D.C. Circuit Court. In February 2016, the U.S. Supreme Court issued an order staying the final CPP rule. In September 2016, the D.C. Circuit Court heard oral arguments in the consolidated challenges to the CPP. The stay will remain in effect until the D.C. Circuit Court reaches its decision and the U.S. Supreme Court either declines to review the lower court’s decision or reaches a decision of its own. In March 2017, President Trump signed an executive order requiring the EPA Administrator to review the CPP rule and if appropriate, publish proposed rules suspending, revising or rescinding it. Accordingly, the EPA has requested that the D.C. Circuit Court hold the litigation in abeyance until the EPA completes its work under the executive order. Parties in the litigation, who support the CPP, have filed briefs opposing the EPA’s motion. A court ruling on the EPA’s motion is expected in the second quarter of 2017. NSP-Wisconsin has undertaken a number of initiatives that reduce GHG emissions and respond to state renewable and energy efficiency goals. The CPP could require additional emission reductions in states in which NSP-Wisconsin operates. If state plans do not provide credit for the investments NSP-Wisconsin has already made to reduce GHG emissions, or if they require additional initiatives or emission reductions, then their requirements would potentially impose additional substantial costs. NSP-Wisconsin cannot predict the costs of compliance with the final rule once it takes effect due to the uncertainty about what, if anything, the final rules may require. NSP-Wisconsin believes compliance costs will be recoverable through regulatory mechanisms. If NSP-Wisconsin’s regulators do not allow recovery of all or a part of the cost of capital investment or the operating and maintenance (O&M) costs incurred to comply with the CPP or cost recovery is not provided in a timely manner, it could have a material impact on results of operations, financial position or cash flows. Legal Contingencies NSP-Wisconsin is involved in various litigation matters that are being defended and handled in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for such losses that are probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution of such matters, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, arising from such current proceedings would have a material effect on NSP-Wisconsin’s financial statements. Unless otherwise required by GAAP, legal fees are expensed as incurred. Employment, Tort and Commercial Litigation Gas Trading Litigation — e prime, inc. (e prime) is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing, but has not engaged in natural gas trading or marketing activities since 2003. Thirteen lawsuits were commenced against e prime and Xcel Energy (and NSP-Wisconsin, in two instances) between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. The cases were consolidated in U.S. District Court in Nevada. Five of the cases have since been settled and seven remain active, which include one multi-district litigation (MDL) matter consisting of a Colorado class (Breckenridge), a Wisconsin class (NSP-Wisconsin), a Kansas class, and two other cases identified as “Sinclair Oil” and “Farmland.” In November 2016, the MDL judge dismissed e prime and Xcel Energy from the Farmland lawsuit, and Farmland has appealed the dismissal. Motions for summary judgment were filed by defendants, including e prime, in all of the remaining lawsuits. In March 2017 the U.S. District Court issued an order dismissing the claims against e prime in the Sinclair lawsuit and denied plaintiffs motions for class certification in the other lawsuits. The U.S. District Court did not grant e prime’s summary judgment motions in the Wisconsin or Colorado cases. Xcel Energy, NSP-Wisconsin and e prime have concluded that a loss is remote.

Borrowings and Other Financing

Borrowings and Other Financing Instruments	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Borrowings and Other Financing Instruments	Borrowings and Other Financing Instruments Commercial Paper — NSP-Wisconsin meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility. Commercial paper outstanding for NSP-Wisconsin was as follows: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2017 Year Ended Dec. 31, 2016 Borrowing limit $ 150 $ 150 Amount outstanding at period end 33 60 Average amount outstanding 52 15 Maximum amount outstanding 98 64 Weighted average interest rate, computed on a daily basis 0.93 % 0.69 % Weighted average interest rate at period end 1.10 0.95 Letters of Credit — NSP-Wisconsin uses letters of credit, generally with terms of one year , to provide financial guarantees for certain operating obligations. At March 31, 2017 and Dec. 31, 2016 , there were no letters of credit outstanding. Credit Facility — In order to use its commercial paper program to fulfill short-term funding needs, NSP-Wisconsin must have a revolving credit facility in place at least equal to the amount of its commercial paper borrowing limit and cannot issue commercial paper in an aggregate amount exceeding available capacity under this credit facility. The line of credit provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings. At March 31, 2017 , NSP-Wisconsin had the following committed credit facility available (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 150 $ 33 $ 117 (a) This credit facility matures in June 2021 . (b) Includes outstanding commercial paper. All credit facility bank borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the credit facility outstanding at March 31, 2017 and Dec. 31, 2016 . Other Short-Term Borrowings — The following table presents the notes payable of Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, to Xcel Energy Inc.: (Amounts in Millions, Except Interest Rates) March 31, 2017 Dec. 31, 2016 Notes payable to affiliates $ 0.5 $ 0.5 Weighted average interest rate at period end 1.20 % 0.95 %

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	Fair Value of Financial Assets and Liabilities Fair Value Measurements The accounting guidance for fair value measurements and disclosures provides a single definition of fair value and requires certain disclosures about assets and liabilities measured at fair value. A hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value is established by this guidance. The three levels in the hierarchy are as follows: Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are highly liquid and actively traded instruments with quoted prices. Level 2 — Pricing inputs are other than quoted prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts or priced with models using highly observable inputs. Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 are those valued with models requiring significant management judgment or estimation. Specific valuation methods include the following: Cash equivalents — The fair values of cash equivalents are generally based on cost plus accrued interest; money market funds are measured using quoted net asset values. Interest rate derivatives — The fair values of interest rate derivatives are based on broker quotes that utilize current market interest rate forecasts. Commodity derivatives — The methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2. When contractual settlements extend to periods beyond those readily observable on active exchanges or quoted by brokers, the significance of the use of less observable forecasts of long-term forward prices and volatilities on a valuation is evaluated, and may result in Level 3 classification. Derivative Instruments Fair Value Measurements NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, for trading purposes and to manage risk in connection with changes in interest rates and utility commodity prices. Interest Rate Derivatives — NSP-Wisconsin enters into various instruments that effectively fix the interest payments on certain floating rate debt obligations or effectively fix the yield or price on a specified benchmark interest rate for an anticipated debt issuance for a specific period. These derivative instruments are generally designated as cash flow hedges for accounting purposes. At March 31, 2017 , accumulated other comprehensive loss related to interest rate derivatives included $0.1 million of net losses expected to be reclassified into earnings during the next 12 months as the related hedged interest rate transactions impact earnings, including forecasted amounts for unsettled hedges, as applicable. Commodity Derivatives — NSP-Wisconsin may enter into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations, as well as for trading purposes. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale. The following table details the gross notional amounts of commodity options at March 31, 2017 and Dec. 31, 2016 : (Amounts in Thousands) (a)(b) March 31, 2017 Dec. 31, 2016 Million British thermal units of natural gas — 255 (a) Amounts are not reflective of net positions in the underlying commodities. (b) Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise. Impact of Derivative Activities on Income and Accumulated Other Comprehensive Loss — There were immaterial pre-tax losses related to interest rate derivatives reclassified from accumulated other comprehensive loss into earnings during the three months ended March 31, 2017 and 2016 . During the three months ended March 31, 2017 and 2016, changes in the fair value of natural gas commodity derivatives resulted in net losses of $0.1 million recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. Natural gas commodity derivatives settlement losses of $0.2 million and $0.6 million were recognized for the three months ended March 31, 2017 and 2016 , respectively, and were subject to purchased natural gas cost recovery mechanisms, which result in reclassifications of derivative settlement gains and losses out of income to a regulatory asset or liability, as appropriate. NSP-Wisconsin had no derivative instruments designated as fair value hedges during the three months ended March 31, 2017 and 2016 . Therefore, no gains or losses from fair value hedges or related hedged transactions were recognized for these periods. Consideration of Credit Risk and Concentrations — NSP-Wisconsin continuously monitors the creditworthiness of the counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Given this assessment, as well as an assessment of the impact of NSP-Wisconsin’s own credit risk when determining the fair value of derivative liabilities, the impact of considering credit risk was immaterial to the fair value of unsettled commodity derivatives presented in the consolidated balance sheets. NSP-Wisconsin employs additional credit risk control mechanisms when appropriate, such as letters of credit, parental guarantees, standardized master netting agreements and termination provisions that allow for offsetting of positive and negative exposures. Credit exposure is monitored and, when necessary, the activity with a specific counterparty is limited until credit enhancement is provided. Recurring Fair Value Measurements — The following table presents for each of the fair value hierarchy levels, NSP-Wisconsin’s derivative assets and liabilities measured at fair value on a recurring basis: Dec. 31, 2016 Fair Value Fair Value Total Counterparty Netting (a) Total (b) (Thousands of Dollars) Level 1 Level 2 Level 3 Current derivative assets Natural gas commodity $ — $ 149 $ — $ 149 $ — $ 149 (a) NSP-Wisconsin nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2016 . The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements. (b) Included in prepayments and other current assets balance of $3.8 million at Dec. 31, 2016, in the consolidated balance sheets. Fair Value of Long-Term Debt As of March 31, 2017 and Dec. 31, 2016 , other financial instruments for which the carrying amount did not equal fair value were as follows: March 31, 2017 Dec. 31, 2016 (Thousands of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 663,235 $ 731,767 $ 663,069 $ 730,284 The fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. The fair value estimates are based on information available to management as of March 31, 2017 and Dec. 31, 2016 , and given the observability of the inputs to these estimates, the fair values presented for long-term debt have been assigned a Level 2.

Other (Expense) Income, Net

Other (Expense) Income, Net	3 Months Ended
	Mar. 31, 2017
Other Income and Expenses [Abstract]
Other (Expense) Income, Net	Other (Expense) Income, Net Other (expense) income, net consisted of the following: Three Months Ended March 31 (Thousands of Dollars) 2017 2016 Interest income $ 143 $ 124 Other nonoperating income 155 158 Insurance policy (expense) income (49 ) 170 Other nonoperating expense (3 ) (3 ) Other (expense) income, net $ 246 $ 449

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information Operating results from the regulated electric utility and regulated natural gas utility are each separately and regularly reviewed by NSP-Wisconsin’s chief operating decision maker. NSP-Wisconsin evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment. NSP-Wisconsin has the following reportable segments: regulated electric utility, regulated natural gas utility and all other. • NSP-Wisconsin’s regulated electric utility segment generates, transmits and distributes electricity primarily in portions of Wisconsin and Michigan. • NSP-Wisconsin’s regulated natural gas utility segment purchases, transports, stores and distributes natural gas primarily in portions of Wisconsin and Michigan. • Revenues from operating segments not included above are below the necessary quantitative thresholds and are therefore included in the all other category. Those primarily include investments in rental housing projects that qualify for low-income housing tax credits. Asset and capital expenditure information is not provided for NSP-Wisconsin’s reportable segments because as an integrated electric and natural gas utility, NSP-Wisconsin operates significant assets that are not dedicated to a specific business segment, and reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis. To report income from operations for regulated electric and regulated natural gas utility segments, the majority of costs are directly assigned to each segment. However, some costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators. A general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising. (Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total Three Months Ended March 31, 2017 Operating revenues (a) $ 216,309 $ 48,347 $ 275 $ — $ 264,931 Intersegment revenues 96 114 — (210 ) — Total revenues $ 216,405 $ 48,461 $ 275 $ (210 ) $ 264,931 Net income $ 15,470 $ 6,545 $ 404 $ — $ 22,419 (Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total Three Months Ended March 31, 2016 Operating revenues (a) $ 211,524 $ 43,020 $ 306 $ — $ 254,850 Intersegment revenues 109 80 — (189 ) — Total revenues $ 211,633 $ 43,100 $ 306 $ (189 ) $ 254,850 Net income $ 11,501 $ 6,092 $ 38 $ — $ 17,631 (a) Operating revenues include $42 million and $41 million of affiliate electric revenue for the three months ended March 31, 2017 and 2016 , respectively.

Benefit Plans and Other Postret

Benefit Plans and Other Postretirement Benefits	3 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Benefit Plans and Other Postretirement Benefits	Benefit Plans and Other Postretirement Benefits Components of Net Periodic Benefit Cost Three Months Ended March 31 2017 2016 2017 2016 (Thousands of Dollars) Pension Benefits Postretirement Health Care Benefits Service cost $ 1,154 $ 1,104 $ 7 $ 6 Interest cost 1,554 1,704 148 163 Expected return on plan assets (2,295 ) (2,289 ) (8 ) (6 ) Amortization of prior service cost (credit) 35 28 (88 ) (88 ) Amortization of net loss 1,462 1,348 109 83 Net benefit cost recognized for financial reporting $ 1,910 $ 1,895 $ 168 $ 158 In January 2017, contributions of $150.0 million were made across four of Xcel Energy’s pension plans, of which $9.0 million was attributable to NSP-Wisconsin. Xcel Energy does not expect additional pension contributions during 2017.

Other Comprehensive Income

Other Comprehensive Income	3 Months Ended
	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Other Comprehensive Income	Other Comprehensive Income Changes in accumulated other comprehensive loss, net of tax, for the three months ended March 31, 2017 and 2016 were as follows: Gains and Losses on Cash Flow Hedges (Thousands of Dollars) Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Accumulated other comprehensive loss at Jan. 1 $ (133 ) $ (209 ) Losses reclassified from net accumulated other comprehensive loss 19 19 Net current period other comprehensive income 19 19 Accumulated other comprehensive loss at March 31 $ (114 ) $ (190 ) Reclassifications from accumulated other comprehensive loss for the three months ended March 31, 2017 and 2016 were as follows: Amounts Reclassified from Accumulated Other Comprehensive Loss (Thousands of Dollars) Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Losses on cash flow hedges: Interest rate derivatives $ 31 (a) $ 32 (a) Total, pre-tax 31 32 Tax benefit (12 ) (13 ) Total amounts reclassified, net of tax $ 19 $ 19 (a) Included in interest charges.

Selected Balance Sheet Data (Ta

Selected Balance Sheet Data (Tables)	3 Months Ended
	Mar. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Accounts Receivable, Net	(Thousands of Dollars) March 31, 2017 Dec. 31, 2016 Accounts receivable, net (a) Accounts receivable $ 69,975 $ 58,896 Less allowance for bad debts (5,077 ) (4,865 ) $ 64,898 $ 54,031
Inventories	(Thousands of Dollars) March 31, 2017 Dec. 31, 2016 Inventories Materials and supplies $ 6,798 $ 6,582 Fuel 4,893 4,743 Natural gas 1,812 6,984 $ 13,503 $ 18,309
Property, Plant and Equipment, Net	(Thousands of Dollars) March 31, 2017 Dec. 31, 2016 Property, plant and equipment, net Electric plant $ 2,520,158 $ 2,499,401 Natural gas plant 299,926 294,986 Common and other property 156,213 156,316 Construction work in progress 135,927 118,822 Total property, plant and equipment 3,112,224 3,069,525 Less accumulated depreciation (1,140,094 ) (1,121,888 ) $ 1,972,130 $ 1,947,637

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the amount of unrecognized tax benefit is as follows: (Millions of Dollars) March 31, 2017 Dec. 31, 2016 Unrecognized tax benefit — Permanent tax positions $ 0.4 $ 0.4 Unrecognized tax benefit — Temporary tax positions 5.0 4.9 Total unrecognized tax benefit $ 5.4 $ 5.3
Tax Benefits Associated with NOL and Tax Credit Carryforwards	The unrecognized tax benefit amounts were reduced by the tax benefits associated with NOL and tax credit carryforwards. The amounts of tax benefits associated with NOL and tax credit carryforwards are as follows: (Millions of Dollars) March 31, 2017 Dec. 31, 2016 NOL and tax credit carryforwards $ (1.2 ) $ (1.2 )

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Guarantees Issued and Outstanding	The following table presents the guarantee issued and outstanding for NSP-Wisconsin: (Millions of Dollars) March 31, 2017 Dec. 31, 2016 Guarantee issued and outstanding $ 1.0 $ 1.0 Current exposure under this guarantee 0.1 0.1

Borrowings and Other Financin25

Borrowings and Other Financing Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
Borrowings and Other Financing Instruments [Abstract]
Credit Facilities	At March 31, 2017 , NSP-Wisconsin had the following committed credit facility available (in millions of dollars): Credit Facility (a) Drawn (b) Available $ 150 $ 33 $ 117 (a) This credit facility matures in June 2021 . (b) Includes outstanding commercial paper.
Commercial Paper
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Commercial paper outstanding for NSP-Wisconsin was as follows: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2017 Year Ended Dec. 31, 2016 Borrowing limit $ 150 $ 150 Amount outstanding at period end 33 60 Average amount outstanding 52 15 Maximum amount outstanding 98 64 Weighted average interest rate, computed on a daily basis 0.93 % 0.69 % Weighted average interest rate at period end 1.10 0.95
Notes Payable To Affiliates
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Other Short-Term Borrowings — The following table presents the notes payable of Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, to Xcel Energy Inc.: (Amounts in Millions, Except Interest Rates) March 31, 2017 Dec. 31, 2016 Notes payable to affiliates $ 0.5 $ 0.5 Weighted average interest rate at period end 1.20 % 0.95 %

Fair Value of Financial Asset26

Fair Value of Financial Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Gross Notional Amounts of Commodity Forwards and Options	The following table details the gross notional amounts of commodity options at March 31, 2017 and Dec. 31, 2016 : (Amounts in Thousands) (a)(b) March 31, 2017 Dec. 31, 2016 Million British thermal units of natural gas — 255 (a) Amounts are not reflective of net positions in the underlying commodities. (b) Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.
Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level	Recurring Fair Value Measurements — The following table presents for each of the fair value hierarchy levels, NSP-Wisconsin’s derivative assets and liabilities measured at fair value on a recurring basis: Dec. 31, 2016 Fair Value Fair Value Total Counterparty Netting (a) Total (b) (Thousands of Dollars) Level 1 Level 2 Level 3 Current derivative assets Natural gas commodity $ — $ 149 $ — $ 149 $ — $ 149 (a) NSP-Wisconsin nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2016 . The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements. (b) Included in prepayments and other current assets balance of $3.8 million at Dec. 31, 2016, in the consolidated balance sheets.
Carrying Amount and Fair Value of Long-term Debt	As of March 31, 2017 and Dec. 31, 2016 , other financial instruments for which the carrying amount did not equal fair value were as follows: March 31, 2017 Dec. 31, 2016 (Thousands of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 663,235 $ 731,767 $ 663,069 $ 730,284

Other (Expense) Income, Net (Ta

Other (Expense) Income, Net (Tables)	3 Months Ended
	Mar. 31, 2017
Other Income and Expenses [Abstract]
Other (Expense) Income, Net	Other (expense) income, net consisted of the following: Three Months Ended March 31 (Thousands of Dollars) 2017 2016 Interest income $ 143 $ 124 Other nonoperating income 155 158 Insurance policy (expense) income (49 ) 170 Other nonoperating expense (3 ) (3 ) Other (expense) income, net $ 246 $ 449

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Results from Operations by Reportable Segment	(Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total Three Months Ended March 31, 2017 Operating revenues (a) $ 216,309 $ 48,347 $ 275 $ — $ 264,931 Intersegment revenues 96 114 — (210 ) — Total revenues $ 216,405 $ 48,461 $ 275 $ (210 ) $ 264,931 Net income $ 15,470 $ 6,545 $ 404 $ — $ 22,419 (Thousands of Dollars) Regulated Electric Regulated Natural Gas All Other Reconciling Eliminations Consolidated Total Three Months Ended March 31, 2016 Operating revenues (a) $ 211,524 $ 43,020 $ 306 $ — $ 254,850 Intersegment revenues 109 80 — (189 ) — Total revenues $ 211,633 $ 43,100 $ 306 $ (189 ) $ 254,850 Net income $ 11,501 $ 6,092 $ 38 $ — $ 17,631 (a) Operating revenues include $42 million and $41 million of affiliate electric revenue for the three months ended March 31, 2017 and 2016 , respectively.

Benefit Plans and Other Postr29

Benefit Plans and Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost Three Months Ended March 31 2017 2016 2017 2016 (Thousands of Dollars) Pension Benefits Postretirement Health Care Benefits Service cost $ 1,154 $ 1,104 $ 7 $ 6 Interest cost 1,554 1,704 148 163 Expected return on plan assets (2,295 ) (2,289 ) (8 ) (6 ) Amortization of prior service cost (credit) 35 28 (88 ) (88 ) Amortization of net loss 1,462 1,348 109 83 Net benefit cost recognized for financial reporting $ 1,910 $ 1,895 $ 168 $ 158

Other Comprehensive Income (Tab

Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Changes in Accumulated Other Comprehensive Loss, Net of Tax	Changes in accumulated other comprehensive loss, net of tax, for the three months ended March 31, 2017 and 2016 were as follows: Gains and Losses on Cash Flow Hedges (Thousands of Dollars) Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Accumulated other comprehensive loss at Jan. 1 $ (133 ) $ (209 ) Losses reclassified from net accumulated other comprehensive loss 19 19 Net current period other comprehensive income 19 19 Accumulated other comprehensive loss at March 31 $ (114 ) $ (190 )
Reclassifications out of Accumulated Other Comprehensive Loss	Reclassifications from accumulated other comprehensive loss for the three months ended March 31, 2017 and 2016 were as follows: Amounts Reclassified from Accumulated Other Comprehensive Loss (Thousands of Dollars) Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Losses on cash flow hedges: Interest rate derivatives $ 31 (a) $ 32 (a) Total, pre-tax 31 32 Tax benefit (12 ) (13 ) Total amounts reclassified, net of tax $ 19 $ 19 (a) Included in interest charges.

Selected Balance Sheet Data, Ac

Selected Balance Sheet Data, Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Accounts Receivable, Net
Accounts receivable	$ 69,975	$ 58,896
Less allowance for bad debts	(5,077)	(4,865)
Accounts receivable, net	$ 64,898	$ 54,031

Selected Balance Sheet Data, In

Selected Balance Sheet Data, Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Public Utilities, Inventory [Line Items]
Inventories	$ 13,503	$ 18,309
Materials and supplies
Public Utilities, Inventory [Line Items]
Inventories	6,798	6,582
Fuel
Public Utilities, Inventory [Line Items]
Inventories	4,893	4,743
Natural gas
Public Utilities, Inventory [Line Items]
Inventories	$ 1,812	$ 6,984

Selected Balance Sheet Data, Pr

Selected Balance Sheet Data, Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 3,112,224	$ 3,069,525
Less accumulated depreciation	(1,140,094)	(1,121,888)
Property, plant and equipment, net	1,972,130	1,947,637
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,520,158	2,499,401
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	299,926	294,986
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	156,213	156,316
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 135,927	$ 118,822

Income Taxes (Details)

Income Taxes (Details) - USD ($)	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2016	Mar. 31, 2017	Sep. 30, 2015	Dec. 31, 2012	Dec. 31, 2016
Unrecognized Tax Benefits [Abstract]
Unrecognized tax benefit — Permanent tax positions		$ 400,000			$ 400,000
Unrecognized tax benefit — Temporary tax positions		5,000,000			4,900,000
Total unrecognized tax benefit		5,400,000			5,300,000
NOL and tax credit carryforwards		(1,200,000)			(1,200,000)
Upper bound of decrease in unrecognized tax benefit that is reasonably possible		2,000,000
Amounts accrued for penalties related to unrecognized tax benefits		0			$ 0
Internal Revenue Service (IRS)
Tax Audits [Abstract]
Year(s) under examination			2012 and 2013	2010 and 2011
Year of carryback claim under examination				2,009
Potential Tax Adjustments		$ 14,000,000
Earliest year subject to examination		2,009
State Jurisdiction (Wisconsin)
Tax Audits [Abstract]
Year(s) under examination	2012 and 2013
Earliest year subject to examination		2,012

Rate Matters Rate Matters (Deta

Rate Matters Rate Matters (Details) - USD ($) $ in Thousands	1 Months Ended						3 Months Ended
	Mar. 31, 2017	Oct. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Feb. 28, 2015	Nov. 30, 2013	Mar. 31, 2017
NSP-Wisconsin | MPSC Proceeding - Michigan 2017 Natural Gas Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 347
Public Utilities, Requested Rate Increase (Decrease), Percentage		6.50%
Public Utilities, Requested Return on Equity, Percentage		10.20%
Public Utilities, Requested Equity Capital Structure, Percentage		52.56%
Public Utilities, Requested Rate Base, Amount		$ 6,400
Public Utilities, Requested Rider Revenue, Amount		$ 129
Public Utilities, Requested Rider Revenue, Percentage		2.40%
NSP-Wisconsin | MPSC Staff | MPSC Proceeding - Michigan 2017 Natural Gas Rate Case [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage	10.00%
Public Utilities, Requested Equity Capital Structure, Percentage	52.56%
NSP-Wisconsin | MPSC Staff | MPSC Proceeding - Michigan 2017 Natural Gas Rate Case, Rates 2017 [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Rate Increase Under the Settlement	$ 266
Public Utilities, Rate Increase Under the Settlement, Percentage	5.00%
NSP-Wisconsin | MPSC Staff | MPSC Proceeding - Michigan 2017 Natural Gas Rate Case, Rates 2018 [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Rate Increase Under the Settlement	$ 140
Public Utilities, Rate Increase Under the Settlement, Percentage	2.50%
NSP-Wisconsin | MPSC Staff | MPSC Proceeding - Michigan 2017 Natural Gas Rate Case, Rates 2019 [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Rate Increase Under the Settlement	$ 143
Public Utilities, Rate Increase Under the Settlement, Percentage	2.50%
NSP-Minnesota | FERC Proceeding, MISO ROE Complaint
Public Utilities, General Disclosures [Line Items]
Public Utilities, Base Return On Equity Charged To Customers Through Transmission Formula Rates					12.38%	12.38%
Public Utilities, ROE Applicable To Transmission Formula Rates In The Regional Transmission Operator's Region, Recommended By Third Parties					8.67%	9.15%
Public Utilities, Maximum Equity Capital Structure Percentage Allowed Per The Complaint						50.00%
NSP-Minnesota | Federal Energy Regulatory Commission (FERC) | FERC Proceeding, MISO ROE Complaint
Public Utilities, General Disclosures [Line Items]
Public Utilities, ROE Applicable To Transmission Formula Rates In The MISO Region, Approved			10.32%
Public Utilities, Length of Refund Period, In Months			15 months
Public Utilities, ROE Applicable To Transmission Formula Rates In The MISO Region, with RTO Adder, Approved							10.82%
Public Utilities, ROE Basis Point Adder, Approved							50
NSP-Minnesota | MPUC, NDPSC, SDPUC, and DOC | FERC Proceeding, MISO ROE Complaint
Public Utilities, General Disclosures [Line Items]
Public Utilities, ROE Applicable To Transmission Formula Rates In The Regional Transmission Operator's Region, Recommended By Third Parties							8.81%
NSP-Minnesota | FERC Staff | FERC Proceeding, MISO ROE Complaint
Public Utilities, General Disclosures [Line Items]
Public Utilities, ROE Applicable To Transmission Formula Rates In The Regional Transmission Operator's Region, Recommended By Third Parties							8.78%
NSP-Minnesota | MISO TOs | FERC Proceeding, MISO ROE Complaint
Public Utilities, General Disclosures [Line Items]
Public Utilities, ROE Applicable To Transmission Formula Rates In The Regional Transmission Operator's Region, Recommended By Third Parties							10.92%
NSP-Minnesota | Administrative Law Judge | FERC Proceeding, MISO ROE Complaint
Public Utilities, General Disclosures [Line Items]
Public Utilities, ROE Applicable To Transmission Formula Rates In The Regional Transmission Operator's Region, Recommended By Third Parties				9.70%

Commitments and Contingencies,

Commitments and Contingencies, Guarantees and Indemnifications (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Assets Held As Collateral	$ 0	$ 0
Payment or Performance Guarantee | Customer Loans for Farm Rewiring Program
Guarantor Obligations [Line Items]
Payment Guarantee Expiration (year)	2,020
Guarantee issued and outstanding	$ 1,000,000	1,000,000
Current exposure under this guarantee	$ 100,000	$ 100,000

Commitments and Contingencies37

Commitments and Contingencies, Environmental Contingencies - Site Contingencies (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)Site	Dec. 31, 2016USD ($)
Ashland MGP Site
Ashland Manufactured Gas Plant (MGP) Site [Abstract]
Number of properties not owned included in superfund site | Site	2
Accrual for Environmental Loss Contingencies, Gross	$ 62.1	$ 64.3
Approved amortization period for recovery of remediation costs in natural gas rates (in years)	10 years
Carrying cost percentage to be applied to unamortized regulatory asset	3.00%
Ashland MGP Site - Phase I Project Area
Ashland Manufactured Gas Plant (MGP) Site [Abstract]
Accrual for Environmental Loss Contingencies, Gross	$ 77.2
Estimated amount spent on cleanup	57.2
Other MGP Sites [Member]
Ashland Manufactured Gas Plant (MGP) Site [Abstract]
Accrual for Environmental Loss Contingencies, Gross	$ 0.1
PSCW Proceeding - Electric and Gas Rate Case 2016 - Gas Rates 2016 | Ashland MGP Site
Ashland Manufactured Gas Plant (MGP) Site [Abstract]
Public Utilities, Approved annual recovery collected through base rates		7.6
PSCW Proceeding - Gas Rate Case 2017 - Gas Rates 2017 [Member] | Ashland MGP Site
Ashland Manufactured Gas Plant (MGP) Site [Abstract]
Public Utilities, Approved annual recovery collected through base rates		$ 12.4

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies - Legal Contingencies (Details) - Gas Trading Litigation	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2009
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	1	13
Loss Contingency, Claims Settled, Number	5
Loss Contingency, Claims Dismissed, Number	7
Loss Contingency, Subset of Cases within Multi-District Litigation, Number	2
NSP-Wisconsin
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number		2

Borrowings and Other Financin39

Borrowings and Other Financing Instruments, Commercial Paper (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Amount outstanding at period end	$ 33,000,000	$ 60,000,000
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	150,000,000	150,000,000
Amount outstanding at period end	33,000,000	60,000,000
Average amount outstanding	52,000,000	15,000,000
Maximum amount outstanding	$ 98,000,000	$ 64,000,000
Weighted average interest rate, computed on a daily basis (percentage)	0.93%	0.69%
Weighted average interest rate at period end (percentage)	1.10%	0.95%

Borrowings and Other Financin40

Borrowings and Other Financing Instruments, Letters of Credit (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 33,000	$ 60,000
Letter of Credit
Line of Credit Facility [Line Items]
Amount outstanding at period end	$ 0	$ 0
Letter of Credit | Letter of Credit
Line of Credit Facility [Line Items]
Term of letters of credit (in years)	1 year

Borrowings and Other Financin41

Borrowings and Other Financing Instruments, Credit Facility (Details) - Credit Facility - USD ($)		3 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Credit Facility	[1]	$ 150,000,000
Drawn	[2]	33,000,000
Available		$ 117,000,000
Maturity Date		Jun. 30, 2021
Direct advances on the credit facility outstanding		$ 0	$ 0
[1]	This credit facility matures in June 2021.
[2]	Includes outstanding commercial paper.

Borrowings and Other Financin42

Borrowings and Other Financing Instruments, Intercompany Borrowing Arrangement and Other Short-Term Borrowings (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Short-term Debt [Line Items]
Notes payable to affiliates	$ 500	$ 500
Notes Payable To Affiliates
Short-term Debt [Line Items]
Notes payable to affiliates	$ 500	$ 500
Weighted average interest rate at period end (percentage)	1.20%	0.95%

Fair Value of Financial Asset43

Fair Value of Financial Assets and Liabilities, Derivative Instruments (Details) MMBTU in Thousands, $ in Millions		Mar. 31, 2017USD ($)MMBTU	Dec. 31, 2016MMBTU
Interest Rate Swap
Interest Rate Derivatives [Abstract]
Amount of accumulated other comprehensive gains (losses) related to interest rate derivatives expected to be reclassified into earnings within the next twelve months | $		$ (0.1)
Natural Gas Commodity (in million British thermal units)
Gross Notional Amounts of Commodity Options [Abstract]
Derivative, Nonmonetary Notional amount | MMBTU	[1],[2]	0	255
[1]	Amounts are not reflective of net positions in the underlying commodities.
[2]	Notional amounts for options are included on a gross basis, but are weighted for the probability of exercise.

Fair Value of Financial Asset44

Fair Value of Financial Assets and Liabilities, Impact of Derivative Activity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Financial Impact of Qualifying Fair Value Hedges on Earnings [Abstract]
Derivative instruments designated as fair value hedges	$ 0	$ 0
Recognized gains (losses) from fair value hedges or related hedged transactions	0	0
Other Derivative Instruments | Natural Gas Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities	(100,000)	(100,000)
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	$ 200,000	$ 600,000

Fair Value of Financial Asset45

Fair Value of Financial Assets and Liabilities, Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Prepayments and other		$ 4,831	$ 3,785
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	[1]		149
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset	[2]		0
Fair Value Measured on a Recurring Basis | Level 1 | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset			0
Fair Value Measured on a Recurring Basis | Level 2 | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset			149
Fair Value Measured on a Recurring Basis | Level 3 | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset			0
Estimate of Fair Value Measurement [Member] | Fair Value Measured on a Recurring Basis
Derivatives, Fair Value [Line Items]
Prepayments and other			3,800
Estimate of Fair Value Measurement [Member] | Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Natural Gas Commodity
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset			$ 149
[1]	Included in prepayments and other current assets balance of $3.8 million at Dec. 31, 2016, in the consolidated balance sheets.
[2]	NSP-Wisconsin nets derivative instruments and related collateral in its consolidated balance sheet when supported by a legally enforceable master netting agreement, and all derivative instruments and related collateral amounts were subject to master netting agreements at Dec. 31, 2016. The counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

Fair Value of Financial Asset46

Fair Value of Financial Assets and Liabilities, Fair Value of Long-Term Debt (Details) - USD ($) $ in Thousands		Mar. 31, 2017	Dec. 31, 2016
Carrying Amount
Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt, including current portion	[1]	$ 663,235	$ 663,069
Fair Value
Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt, including current portion	[1]	$ 731,767	$ 730,284
[1]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM0OTA5MGEyYmYzNTQ4MTM5YmQ3ZGRkZGU5NWFiODk3fFRleHRTZWxlY3Rpb246N0NEQTM3RkNBMDMxOUM0RjRERTgyRkQ2MUE4MzVBNEMM}

Other (Expense) Income, Net (De

Other (Expense) Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other Income and Expenses [Abstract]
Interest income	$ 143	$ 124
Other nonoperating income	155	158
Insurance policy (expense) income	(49)	170
Other nonoperating expense	(3)	(3)
Other (expense) income, net	$ 246	$ 449

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Operating revenues		$ 264,931	$ 254,850
Net income (loss)		22,419	17,631
Affiliate electric revenue		42,000	41,000
Regulated Electric
Segment Reporting Information [Line Items]
Operating revenues		216,405	211,633
Net income (loss)		15,470	11,501
Regulated Natural Gas
Segment Reporting Information [Line Items]
Operating revenues		48,461	43,100
Net income (loss)		6,545	6,092
All Other
Segment Reporting Information [Line Items]
Operating revenues		275	306
Net income (loss)		404	38
Operating Segments
Segment Reporting Information [Line Items]
Operating revenues	[1]	264,931	254,850
Operating Segments | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenues	[1]	216,309	211,524
Operating Segments | Regulated Natural Gas
Segment Reporting Information [Line Items]
Operating revenues		48,347	43,020
Operating Segments | All Other
Segment Reporting Information [Line Items]
Operating revenues		275	306
Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues		(210)	(189)
Net income (loss)		0	0
Intersegment Eliminations | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenues		96	109
Intersegment Eliminations | Regulated Natural Gas
Segment Reporting Information [Line Items]
Operating revenues		114	80
Intersegment Eliminations | All Other
Segment Reporting Information [Line Items]
Operating revenues		$ 0	$ 0
[1]	(a) Operating revenues include $42 million and $41 million of affiliate electric revenue for the three months ended March 31, 2017 and 2016, respectively.

Benefit Plans and Other Postr49

Benefit Plans and Other Postretirement Benefits (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2017USD ($)Plan	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		$ 1,154	$ 1,104
Interest cost		1,554	1,704
Expected return on plan assets		(2,295)	(2,289)
Amortization of prior service cost (credit)		35	28
Amortization of net loss		1,462	1,348
Net benefit cost recognized for financial reporting		1,910	1,895
Total contributions to the pension plans during the period	$ 9,000
Postretirement Health Care Benefits
Components of Net Periodic Benefit Cost [Abstract]
Service cost		7	6
Interest cost		148	163
Expected return on plan assets		(8)	(6)
Amortization of prior service cost (credit)		(88)	(88)
Amortization of net loss		109	83
Net benefit cost recognized for financial reporting		$ 168	$ 158
Xcel Energy Inc. | Pension Benefits
Components of Net Periodic Benefit Cost [Abstract]
Total contributions to the pension plans during the period	$ 150,000
Number of Xcel Energy's pension plans to which contributions were made | Plan	4

Other Comprehensive Income (Det

Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	$ 811,850
Accumulated other comprehensive loss at end of period	836,216
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period	(133)	$ (209)
Losses reclassified from net accumulated other comprehensive loss	19	19
Net current period other comprehensive income	19	19
Accumulated other comprehensive loss at end of period	$ (114)	$ (190)

Other Comprehensive Income (Rec

Other Comprehensive Income (Reclassification from AOCI) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total, pre-tax		$ (36,176)	$ (28,450)
Tax benefit		13,757	10,819
Gains and Losses on Cash Flow Hedges | Amounts Reclassified from Accumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total, pre-tax		31	32
Tax benefit		(12)	(13)
Total, net of tax		19	19
Gains and Losses on Cash Flow Hedges | Interest Rate Derivatives | Amounts Reclassified from Accumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest charges	[1]	$ 31	$ 32
[1]	Included in interest charges.