Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Earliest Open Tax Years Subject to Examination by State Taxing Authorities in the Major Operating Jurisdictions

State Audits—Xcel Energy files consolidated state tax returns based on income in its major operating jurisdictions of Colorado, Minnesota, Texas, and Wisconsin, and various other state income-based tax returns. As of Dec. 31, 2016, Xcel Energy’s earliest open tax years that are subject to examination by state taxing authorities in its major operating jurisdictions were as follows:

State	Year
Colorado	2009
Minnesota	2009
Texas	2009
Wisconsin	2012

Reconciliation of Unrecognized Tax Benefits

A reconciliation of the amount of unrecognized tax benefit is as follows:

(Millions of Dollars)	Dec. 31, 2016		Dec. 31, 2015
Unrecognized tax benefit — Permanent tax positions	$	29.6	$	25.8
Unrecognized tax benefit — Temporary tax positions	104.1		94.9
Total unrecognized tax benefit	$	133.7	$	120.7

A reconciliation of the beginning and ending amount of unrecognized tax benefit is as follows:

(Millions of Dollars)	2016			2015			2014
Balance at Jan. 1	$	120.7		$	66.5		$	41.2
Additions based on tax positions related to the current year	8.2			27.1			28.7
Reductions based on tax positions related to the current year	(0.3		)	(4.5		)	(2.0		)
Additions for tax positions of prior years	9.8			34.8			16.0
Reductions for tax positions of prior years	(4.7		)	(2.9		)	(6.0		)
Settlements with taxing authorities	—			(0.3		)	(9.6		)
Lapse of applicable statutes of limitations	—			—			(1.8		)
Balance at Dec. 31	$	133.7		$	120.7		$	66.5

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)	Dec. 31, 2016			Dec. 31, 2015
NOL and tax credit carryforwards	$	(43.8	)	$	(36.7	)

Interest Payable related to Unrecognized Tax Benefits [Table Text Block]

The payable for interest related to unrecognized tax benefits is partially offset by the interest benefit associated with NOL and tax credit carryforwards. A reconciliation of the beginning and ending amount of the payable for interest related to unrecognized tax benefits reported are as follows:

(Millions of Dollars)	2016			2015			2014
Payable for interest related to unrecognized tax benefits at Jan. 1	$	(0.1	)	$	(0.3	)	$	(0.6	)
Interest (expense) income related to unrecognized tax benefits	(3.3		)	0.2			0.3
Payable for interest related to unrecognized tax benefits at Dec. 31	$	(3.4	)	$	(0.1	)	$	(0.3	)

NOL and Tax Credit Carryforwards

Other Income Tax Matters — NOL amounts represent the amount of the tax loss that is carried forward and tax credits represent the deferred tax asset. NOL and tax credit carryforwards as of Dec. 31 were as follows:

(Millions of Dollars)	2016			2015
Federal NOL carryforward	$	1,916		$	2,153
Federal tax credit carryforwards	424			360
State NOL carryforwards	1,949			2,124
Valuation allowances for state NOL carryforwards	(59		)	(65		)
State tax credit carryforwards, net of federal detriment (a)	74			45
Valuation allowances for state credit carryforwards, net of federal benefit (b)	(54		)	(24		)

^(a)  State tax credit carryforwards are net of federal detriment of $40 million and $24 million as of Dec. 31, 2016 and 2015, respectively.

^(b)  Valuation allowances for state tax credit carryforwards were net of federal benefit of $29 million and $13 million as of Dec. 31, 2016 and 2015, respectively.

Schedule of Effective Income Tax Rate Reconciliation

Total income tax expense from operations differs from the amount computed by applying the statutory federal income tax rate to income before income tax expense. The following reconciles such differences for the years ending Dec. 31:

	2016		2015		2014
Federal statutory rate	35.0	%	35.0	%	35.0	%
Increases (decreases) in tax from:
Tax credits recognized, net of federal income tax expense	(4.2	)	(2.7	)	(2.6	)
Regulatory differences — utility plant items	(0.5	)	(1.0	)	(1.3	)
State income taxes, net of federal income tax benefit	4.2		4.1		4.0
Change in unrecognized tax benefits	0.2		0.6		0.2
NOL carryback	—		(0.3	)	(0.9	)
Other, net	(0.6	)	(0.2	)	(0.5	)
Effective income tax rate	34.1	%	35.5	%	33.9	%

Schedule of Components of Income Tax Expense (Benefit)

The components of Xcel Energy’s income tax expense for the years ending Dec. 31 were:

(Thousands of Dollars)	2016			2015			2014
Current federal tax benefit	$	(2,809	)	$	(36,129	)	$	(73,160	)
Current state tax (benefit) expense	(3,345		)	2,324			9,225
Current change in unrecognized tax expense	5,924			45,933			23,915
Deferred federal tax expense	476,439			480,078			505,236
Deferred state tax expense	112,308			92,132			84,787
Deferred change in unrecognized tax benefit	(2,097		)	(36,342		)	(20,645		)
Deferred investment tax credits	(5,203		)	(5,277		)	(5,543		)
Total income tax expense	$	581,217		$	542,719		$	523,815

The components of deferred income tax expense for the years ending Dec. 31 were:

(Thousands of Dollars)	2016			2015			2014
Deferred tax expense excluding items below	$	630,877		$	546,664		$	616,934
Amortization and adjustments to deferred income taxes on income tax regulatory assets and liabilities	(44,638		)	(11,810		)	(48,674		)
Tax benefit allocated to OCI	415			1,013			1,117
Other	(4		)	1			1
Deferred tax expense	$	586,650		$	535,868		$	569,378

Schedule of Deferred Tax Assets and Liabilities

The components of Xcel Energy’s net deferred tax liability at Dec. 31 were as follows:

(Thousands of Dollars)	2016			2015
Deferred tax liabilities:
Differences between book and tax bases of property	$	7,696,833		$	7,119,023
Regulatory assets	313,034			308,130
Other	186,007			229,005
Total deferred tax liabilities	$	8,195,874		$	7,656,158
Deferred tax assets:
NOL carryforward	$	753,851		$	851,242
Tax credit carryforward	497,518			404,738
Rate refund	32,810			50,441
Environmental remediation	30,288			38,663
Regulatory liabilities	28,249			36,257
Deferred investment tax credits	27,436			29,650
Deferred fuel costs	11,387			57,220
NOL and tax credit valuation allowances	(57,515		)	(27,679		)
Other	87,531			62,184
Total deferred tax assets	$	1,411,555		$	1,502,716
Net deferred tax liability	$	6,784,319		$	6,153,442