Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Income Tax Disclosure [Abstract]

Components of income tax expense

Components of income tax expense are as follows (in millions):

	Year Ended December 31,
	2016			2015		2014
Current income tax expense:
State income tax	$	2		$	1	$	1
Canadian federal and provincial income tax	83			83		70
Total current income tax expense	$	85		$	84	$	71
Deferred income tax expense/(benefit):
Federal income tax	$	57		$	75	$	38
State income tax	(4		)	7		3
Canadian federal and provincial income tax	(60		)	16		100
Total deferred income tax expense/(benefit)	$	(7	)	$	98	$	141
Total income tax expense	$	78		$	182	$	212

Summary of differences between income tax expense based on the statutory federal income tax rate and the effective income tax expense

The difference between income tax expense based on the statutory federal income tax rate and our effective income tax expense is summarized as follows (in millions):

	Year Ended December 31,
	2016			2015			2014
Income before tax	$	738		$	991		$	1,540
Net income attributable to noncontrolling interests	(566		)	(691		)	(1,258		)
Income taxes attributable to noncontrolling interests	(25		)	(100		)	(171		)
	$	147		$	200		$	111
Federal statutory income tax rate	35		%	35		%	35		%
Income tax at statutory rate	$	51		$	70		$	39
Deferred tax rate adjustment	(1		)	8			—
State income tax, net of federal benefit	3			4			2
Income taxes attributable to noncontrolling interests:
Canadian federal and provincial income tax	$	10		$	85		$	154
Canadian withholding tax	13			14			16
State income tax	2			1			1
Total income tax expense	$	78		$	182		$	212

Deferred tax assets and liabilities

Deferred tax assets and liabilities are aggregated by the applicable tax paying entity and jurisdiction and result from the following (in millions):

	December 31,
	2016			2015
Deferred tax assets:
Investment in partnerships	$	1,685		$	1,730
Net operating losses	191			105
Derivative instruments	49			—
Book accruals in excess of current tax deductions	24			20
Total deferred tax assets	1,949			1,855
Deferred tax liabilities:
Derivative instruments	—			(30		)
Property and equipment in excess of tax values	(394		)	(312		)
Other	(41		)	(41		)
Total deferred tax liabilities	(435		)	(383		)
Net deferred tax assets	$	1,514		$	1,472
Balance sheet classification of deferred tax assets/(liabilities):
Deferred tax asset	$	1,876		$	1,835
Other long-term liabilities and deferred credits	(362		)	(363		)
	$	1,514		$	1,472