Spectra Energy 10-K 24 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2016	Jan. 31, 2017	Jun. 30, 2016
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	SE
Entity Registrant Name	SPECTRA ENERGY CORP.
Entity Central Index Key	1,373,835
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		702,293,575
Entity Public Float			$ 26

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Operating Revenues
Transportation, storage and processing of natural gas	$ 3,251		$ 3,225		$ 3,291
Distribution of natural gas	1,144		1,320		1,583
Sales of natural gas liquids	68		209		497
Transportation of crude oil	359		357		302
Other	94		123		230
Total operating revenues	4,916		5,234		5,903
Operating Expenses
Natural gas and petroleum products purchased	582		835		1,219
Operating, maintenance and other	1,603		1,504		1,570
Depreciation and amortization	774		764		796
Property and other taxes	372		353		393
Impairment of goodwill and other	0		349		0
Total operating expenses	3,331		3,805		3,978
Gain (Loss) on Sales of Other Assets and Other, net	(26)		4		(1)
Operating Income	1,559		1,433		1,924
Other Income and Expenses
Earnings (loss) from equity investments	97		(290)		361
Other income and expenses, net	174		114		59
Total other income and expenses	271		(176)		420
Interest Expense	594		636		679
Earnings Before Income Taxes	1,236		621		1,665
Income Tax Expense	216		161		382
Net Income	1,020		460		1,283
Net Income—Noncontrolling Interests	327		264		201
Net Income—Controlling Interests	$ 693		$ 196		$ 1,082
Weighted-average shares outstanding
Basic	694		671		671
Diluted	696		672		672
Earnings per share
Basic and diluted	$ 1	[1]	$ 0.29	[1]	$ 1.61
Dividends per share	$ 1.62		$ 1.48		$ 1.375
[1]	Quarterly earnings-per-share amounts are stand-alone calculations and may not be additive to full-year amounts due to rounding.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Income	$ 1,020	$ 460	$ 1,283
Other comprehensive income (loss):
Foreign currency translation adjustments	150	(950)	(548)
Non-cash mark-to-market net gain on hedges	0	0	4
Reclassification of cash flow hedges into earnings	0	0	5
Pension and benefits impact (net of tax benefit (expense) of $12, $1 and $14, respectively)	(24)	5	(47)
Other	0	1	0
Total other comprehensive income (loss)	126	(944)	(586)
Total Comprehensive Income (Loss), net of tax	1,146	(484)	697
Less: Comprehensive Income—Noncontrolling Interests	330	251	194
Comprehensive Income (Loss)—Controlling Interests	$ 816	$ (735)	$ 503

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Tax benefit (expense) on pension and benefits impact	$ 12	$ 1	$ 14

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents		$ 305	$ 213
Receivables (net of allowance for doubtful accounts of $10 and $11 at December 31, 2016 and 2015, respectively)		1,003	806
Inventory		253	307
Fuel tracker		6	41
Other		205	281
Total current assets		1,772	1,648
Investments and Other Assets
Investments in and loans to unconsolidated affiliates		2,780	2,592
Goodwill		4,181	4,154
Other		393	310
Total investments and other assets		7,354	7,056
Property, Plant and Equipment
Cost		33,555	29,843
Less accumulated depreciation and amortization		7,347	6,925
Net property, plant and equipment		26,208	22,918
Regulatory Assets and Deferred Debits		1,508	1,301
Total Assets		36,842	32,923
Current Liabilities
Accounts payable		828	511
Commercial paper	[1],[2]	1,453	1,112
Taxes accrued		86	78
Interest accrued		185	179
Current maturities of long-term debt		551	652
Other		802	860
Total current liabilities		3,905	3,392
Long-term Debt		13,624	12,892
Deferred Credits and Other Liabilities
Deferred income taxes		5,769	5,445
Regulatory and other		1,443	1,323
Total deferred credits and other liabilities		7,212	6,768
Commitments and Contingencies
Preferred Stock of Subsidiaries		562	339
Equity
Preferred stock, $0.001 par, 22 million shares authorized, no shares outstanding		0	0
Common stock, $0.001 par, 1 billion shares authorized, 702 million and 671 million shares outstanding at December 31, 2016 and 2015, respectively		1	1
Additional paid-in capital		5,995	5,053
Retained earnings		1,307	1,741
Accumulated other comprehensive loss		(146)	(269)
Total controlling interests		7,157	6,526
Noncontrolling interests		4,382	3,006
Total equity		11,539	9,532
Total Liabilities and Equity		$ 36,842	$ 32,923
[1]	The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015.
[2]	Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Receivables, allowance for doubtful accounts	$ 10	$ 11
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	22,000,000	22,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares outstanding	702,000,000	671,000,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 1,020	$ 460	$ 1,283
Depreciation and amortization	799	778	809
Impairment charges	0	349	0
Gain (Loss) on Sales of Other Assets and Other, net	26	(4)	1
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax expense	198	88	388
(Earnings) loss from equity investments	(97)	290	(361)
Distributions from equity investments	111	161	380
Decrease (increase) in
Receivables	(42)	141	(9)
Inventory	14	(40)	(106)
Other current assets	77	43	(143)
Increase (decrease) in
Accounts payable	55	26	25
Taxes accrued	4	23	28
Other current liabilities	(5)	(15)	3
Other, assets	(212)	(102)	(34)
Other, liabilities	78	49	(43)
Net cash provided by operating activities	2,026	2,247	2,221
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(3,623)	(2,848)	(2,028)
Investments in and loans to unconsolidated affiliates	(251)	(124)	(259)
Dispositions	207	0	0
Purchase of intangible, net	(80)	0	0
Purchases of held-to-maturity securities	(633)	(668)	(790)
Proceeds from sales and maturities of held-to-maturity securities	670	695	815
Purchases of available-for-sale securities	(738)	(95)	(13)
Proceeds from sales and maturities of available-for-sale securities	735	87	7
Distributions from equity investments	50	451	266
Distribution to equity investment	(148)	(248)	0
Other changes in restricted funds	(20)	(33)	(1)
Other	1	1	0
Net cash used in investing activities	(3,830)	(2,782)	(2,003)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	1,183	1,585	1,028
Payments for the redemption of long-term debt	(652)	(285)	(1,184)
Net increase (decrease) in commercial paper	319	(439)	574
Distributions to noncontrolling interests	(246)	(198)	(175)
Contributions from noncontrolling interests	743	248	145
Proceeds from the issuances of Spectra Energy common stock	879	0	0
Proceeds from the issuances of Spectra Energy Partners, LP common units	579	546	327
Proceeds from the issuance of Westcoast Energy Inc. preferred stock	229	84	0
Dividends paid on common stock	(1,127)	(996)	(925)
Other	(17)	(5)	11
Net cash provided by (used in) financing activities	1,890	540	(199)
Effect of exchange rate changes on cash	6	(7)	(5)
Net increase (decrease) in cash and cash equivalents	92	(2)	14
Cash and cash equivalents at beginning of period	213	215	201
Cash and cash equivalents at end of period	305	213	215
Supplemental Disclosures
Cash paid for interest, net of amount capitalized	572	623	684
Net cash paid (refunds received) for income taxes	(5)	29	(8)
Property, plant and equipment non-cash accruals	$ 392	$ 192	$ 125

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock	Additional Paid-in Capital		Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning Balance at Dec. 31, 2013	$ 10,323	$ 1	$ 4,869		$ 2,383	$ 1,241	$ 1,829
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,283				1,082		201
Other comprehensive income (loss)	(586)					(579)	(7)
Dividends on common stock	(924)				(924)
Stock-based compensation	19		19
Distributions to noncontrolling interests	(175)						(175)
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	145						145
Spectra Energy common stock issued	11		11
Spectra Energy Partners, LP common units issued/retired	297		49	[1]			248
Transfer of interests in subsidiaries	2		3				(1)
Other, net	3		5				(2)
Ending Balance at Dec. 31, 2014	10,398	1	4,956		2,541	662	2,238
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	460				196		264
Other comprehensive income (loss)	(944)					(931)	(13)
Dividends on common stock	(996)				(996)
Stock-based compensation	21		21
Distributions to noncontrolling interests	(200)						(200)
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	248						248
Spectra Energy common stock issued	3		3
Spectra Energy Partners, LP common units issued/retired	530		(105)	[1]			635
Transfer of interests in subsidiaries	0		166				(166)
Other, net	12		12				0
Ending Balance at Dec. 31, 2015	9,532	1	5,053		1,741	(269)	3,006
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,020				693		327
Other comprehensive income (loss)	126					123	3
Dividends on common stock	(1,127)				(1,127)
Stock-based compensation	31		31
Distributions to noncontrolling interests	(251)						(251)
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	743						743
Spectra Energy common stock issued	879		879
Spectra Energy Partners, LP common units issued/retired	559		31	[1]			528
Other, net	27		1				26
Ending Balance at Dec. 31, 2016	$ 11,539	$ 1	$ 5,995		$ 1,307	$ (146)	$ 4,382
[1]	See Note 2 for further discussion.

Summary of Operations and Signi

Summary of Operations and Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Operations and Significant Accounting Policies	Summary of Operations and Significant Accounting Policies The terms “we,” “our,” “us” and “Spectra Energy” as used in this report refer collectively to Spectra Energy Corp and its subsidiaries unless the context suggests otherwise. These terms are used for convenience only and are not intended as a precise description of any separate legal entity within Spectra Energy. The term “Spectra Energy Partners” refers to our Spectra Energy Partners operating segment. The term “SEP” refers to Spectra Energy Partners, LP, our master limited partnership. On September 6, 2016, we announced that we entered into a definitive merger agreement with Enbridge Inc. (Enbridge) under which Enbridge and Spectra Energy will combine in a stock-for-stock merger transaction, which values Spectra Energy’s stock at approximately $28 billion , based on the closing price of Enbridge’s common shares as of September 2, 2016 . This transaction was approved by the boards of directors and shareholders of both Spectra Energy and Enbridge and has received all necessary regulatory approvals. The transaction is expected to close on February 27, 2017. Upon completion of the proposed merger, Spectra Energy shareholders will receive 0.984 Enbridge common shares for each share of Spectra Energy stock they own. The consideration to be received by Spectra Energy shareholders is valued at $40.33 per Spectra Energy share, based on the closing price of Enbridge common shares as of September 2, 2016 , representing an approximate 11.5% premium to the closing price of Spectra Energy stock as of September 2, 2016 . Upon completion of the merger, Enbridge shareholders are expected to own approximately 57% of the combined company and Spectra Energy shareholders are expected to own approximately 43% . Nature of Operations. Spectra Energy Corp, through its subsidiaries and equity affiliates, owns and operates a large and diversified portfolio of complementary natural gas-related energy assets, and owns and operates a crude oil pipeline system that connects Canadian and United States (U.S.) producers to refineries in the U.S. Rocky Mountain and Midwest regions. We currently operate in three key areas of the natural gas industry: gathering and processing, transmission and storage, and distribution. We provide transmission and storage of natural gas to customers in various regions of the northeastern and southeastern U.S., the Maritime Provinces in Canada, the Pacific Northwest in the U.S. and Canada, and in the province of Ontario, Canada. We also provide natural gas sales and distribution services to retail customers in Ontario, and natural gas gathering and processing services to customers in western Canada. We also own a 50% interest in DCP Midstream, LLC (DCP Midstream), based in Denver, Colorado, one of the leading natural gas gatherers in the U.S. and one of the largest U.S. producers and marketers of natural gas liquids (NGLs). Basis of Presentation. The accompanying Consolidated Financial Statements include our accounts and the accounts of our majority-owned subsidiaries, after eliminating intercompany transactions and balances. Use of Estimates. To conform with generally accepted accounting principles (GAAP) in the U.S., we make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and Notes to Consolidated Financial Statements. Although these estimates are based on our best available knowledge at the time, actual results could differ. Fair Value Measurements. We measure the fair value of financial assets and liabilities by maximizing the use of observable inputs and minimizing the use of unobservable inputs. Fair value is the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Cost-Based Regulation. The economic effects of regulation can result in a regulated company recording assets for costs that have been or are expected to be approved for recovery from customers or recording liabilities for amounts that are expected to be returned to customers or for instances where the regulator provides current rates that are intended to recover costs that are expected to be incurred in the future. Accordingly, we record assets and liabilities that result from the regulated ratemaking process that may not be recorded under GAAP for non-regulated entities. We continually assess whether regulatory assets are probable of future recovery by considering factors such as applicable regulatory changes and recent rate orders to other regulated entities. Based on this assessment, we believe our existing regulatory assets are probable of recovery. These regulatory assets and liabilities are mostly classified in the Consolidated Balance Sheets as Regulatory Assets and Deferred Debits, and Deferred Credits and Other Liabilities—Regulatory and Other. We evaluate our regulated assets, and consider factors such as regulatory changes and the effect of competition. If cost-based regulation ends or competition increases, we may have to reduce our asset balances to reflect a market basis less than cost and write-off the associated regulatory assets and liabilities. See Note 5 for further discussion. Foreign Currency Translation. The Canadian dollar has been determined to be the functional currency of our Canadian operations based on an assessment of the economic circumstances of those operations. Assets and liabilities of our Canadian operations are translated into U.S. dollars at current exchange rates. Translation adjustments resulting from fluctuations in exchange rates are included as a separate component of Other Comprehensive Income on the Consolidated Statements of Comprehensive Income. Revenue and expense accounts of these operations are translated at average monthly exchange rates prevailing during the periods. Gains and losses arising from transactions denominated in currencies other than the functional currency are included in the results of operations of the period in which they occur. Foreign currency transaction losses totaled $1 million in 2016 and $6 million in 2015 and gains totaled $3 million in 2014 , and are included in Other Income and Expenses, Net on the Consolidated Statements of Operations. Deferred U.S. taxes related to translation gains and losses have not been provided on those Canadian operations where we expect the earnings to be indefinitely reinvested. Revenue Recognition. Revenues from the transmission, storage, processing, distribution and sales of natural gas, from the sales of NGLs and from the transportation and storage of crude oil are generally recognized when either the service is provided or the product is delivered. Revenues related to these services provided or products delivered but not yet billed are estimated each month. These estimates are generally based on contract data, regulatory information, estimated distribution usage based on historical data adjusted for heating degree days, commodity prices and preliminary throughput and allocation measurements. Final bills for the current month are billed and collected in the following month. Differences between actual and estimated revenues are immaterial. There were no customers accounting for 10% or more of consolidated revenues during 2016 , 2015 or 2014 . We also have certain customer contracts with billed amounts that decline annually over the terms of the contracts. Differences between the amounts billed and recognized are deferred on the Consolidated Balance Sheets. Stock-Based Compensation. For employee awards, equity-classified and liability-classified stock-based compensation cost is measured at the grant date based on the fair value of the award. Liability-classified stock-based compensation cost is remeasured at each reporting period until settlement. Related compensation expense is recognized over the requisite service period, which generally begins on the date the award is granted through the earlier of the date the award vests, the date the employee becomes retirement-eligible or the date the market or performance condition of the award is met. Awards, including stock options, granted to employees that are retirement-eligible are deemed to have vested immediately upon issuance, and therefore, compensation cost for those awards is recognized on the date such awards are granted. See Note 25 for further discussion. Pension and Other Post-Retirement Benefits. We fully recognize the overfunded or underfunded status of our consolidating subsidiaries’ pension and other post-retirement benefit plans as Investments and Other Assets—Other, Current Liabilities—Other or Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets, as appropriate. A plan’s funded status is the difference between the fair value of plan assets and the plan’s projected benefit obligation. We record deferred plan costs and income (unrecognized losses and gains, and unrecognized prior service costs and credits) in Accumulated Other Comprehensive Income (AOCI) on the Consolidated Statements of Equity, until they are amortized and recognized as a component of benefit expense within Operating, Maintenance and Other in the Consolidated Statements of Operations. See Note 26 for further discussion. Allowance for Funds Used During Construction (AFUDC). AFUDC, which represents the estimated debt and equity costs of capital funds necessary to finance the construction of certain new regulated facilities, consists of two components, an equity component and an interest expense component. After construction is completed, we are permitted to recover these costs through inclusion in the rate base and in the depreciation provision. AFUDC is capitalized as a component of Property, Plant and Equipment—Cost in the Consolidated Balance Sheets, with offsetting credits to the Consolidated Statements of Operations through Other Income and Expenses, Net for the equity component and Interest Expense for the interest expense component. The total amount of AFUDC included in the Consolidated Statements of Operations was $232 million in 2016 (an equity component of $164 million and an interest expense component of $68 million ), $143 million in 2015 (an equity component of $111 million and an interest expense component of $32 million ) and $72 million in 2014 (an equity component of $53 million and an interest expense component of $19 million ). The equity component of AFUDC, a non-cash item, is included as a reconciling item to net income within Cash Flows from Operating Activities—Other, Assets in the Consolidated Statements of Cash Flows. Income Taxes. Deferred income taxes are recognized for differences between the financial reporting and tax bases of assets and liabilities at enacted statutory tax rates in effect for the years in which the differences are expected to reverse. The effect on deferred taxes of a change in tax rates is recognized in income in the period that includes the enactment date. Actual income taxes could vary from these estimates due to future changes in income tax law or results from the final review of tax returns by federal, state or foreign tax authorities. Financial statement effects on tax positions are recognized in the period in which it is more likely than not that the position will be sustained upon examination, the position is effectively settled or when the statute of limitations to challenge the position has expired. Interest and penalties related to unrecognized tax benefits are recorded as interest expense and other expense, respectively. Cash and Cash Equivalents. Highly liquid investments with original maturities of three months or less at the date of acquisition are considered cash equivalents, except for the investments that were pledged as collateral against long-term debt as discussed in Note 17 and any investments that are considered restricted funds. Inventory. Inventory consists of natural gas held in storage for transmission and processing, and also includes materials and supplies. The NGLs previously included in inventory were disposed of as part of the sale of the Empress NGL operations (Empress) on August 4, 2016. See Note 3 for further discussion related to the sale of Empress. Natural gas inventories primarily relate to the Distribution segment in Canada and are valued at costs approved by the regulator, the Ontario Energy Board (OEB). The difference between the approved price and the actual cost of gas purchased is recorded in either Fuel Tracker or Other Current Liabilities on the Consolidated Balance Sheets, as appropriate, for future disposition with customers, subject to approval by the OEB. The remaining inventory is recorded at the lower of cost or market, primarily using average cost. Natural Gas Imbalances. The Consolidated Balance Sheets include balances as a result of differences in gas volumes received and delivered for customers. Since settlement of certain imbalances is in-kind, changes in their balances do not have an effect on our Consolidated Statements of Cash Flows. Receivables include $407 million and $291 million as of December 31, 2016 and December 31, 2015, respectively, and Other Current Liabilities include $382 million and $287 million as of December 31, 2016 and December 31, 2015, respectively, related to gas imbalances. Most natural gas volumes owed to or by us are valued at natural gas market index prices as of the balance sheet dates. Risk Management and Hedging Activities and Financial Instruments. Currently, our use of derivative instruments is primarily limited to interest rate positions. Prior to the sale of Empress on August 4, 2016, we maintained a commodity hedging program at the Western Canada Transmission & Processing segment. All derivative instruments that do not qualify for the normal purchases and normal sales exception are recorded on the Consolidated Balance Sheets at fair value. Cash inflows and outflows related to derivative instruments are a component of Cash Flows From Operating Activities in the accompanying Consolidated Statements of Cash Flows. Fair Value Hedges. Derivatives may be designated as a hedge of a recognized asset, liability or firm commitment (fair value hedge). For all hedge contracts, we prepare documentation of the hedge in accordance with accounting standards and assess whether the hedge contract is highly effective using regression analysis, both at inception and on a quarterly basis, in offsetting changes in fair values of hedged items. We document hedging activity by instrument type and risk management strategy. For derivatives designated as fair value hedges, we recognize the gain or loss on the derivative instrument, as well as the offsetting gain or loss on the hedged item in earnings, to the extent effective, in the current period. In the event the hedge is not effective, there is no offsetting gain or loss recognized in earnings for the hedged item. All derivatives designated and accounted for as hedges are classified in the same category as the item being hedged in the Consolidated Statements of Cash Flows. All components of each derivative gain or loss are included in the assessment of hedge effectiveness. Investments. We may actively invest a portion of our available cash and restricted funds balances in various financial instruments, including taxable or tax-exempt debt securities. In addition, we invest in short-term money market securities, some of which are restricted due to debt collateral or insurance requirements. Investments in available-for-sale (AFS) securities are carried at fair value and investments in held-to-maturity (HTM) securities are carried at cost. Investments in money market securities are also accounted for at fair value. Realized gains and losses, and dividend and interest income related to these securities, including any amortization of discounts or premiums arising at acquisition, are included in earnings. The costs of securities sold are determined using the specific identification method. Purchases and sales of AFS and HTM securities are presented on a gross basis within Cash Flows From Investing Activities in the accompanying Consolidated Statements of Cash Flows. Goodwill. We perform our goodwill impairment test annually and evaluate goodwill when events or changes in circumstances indicate that its carrying value may not be recoverable. In 2015, we recorded goodwill impairment charges of $270 million for BC Field Services and $63 million for Empress associated with the Westcoast Energy Inc. (Westcoast) acquisition in 2002. No impairments of goodwill were recorded in 2016 or 2014. See Note 13 for further discussion. We perform our annual review for goodwill impairment at the reporting unit level, which is identified by assessing whether the components of our operating segments constitute businesses for which discrete financial information is available, whether segment management regularly reviews the operating results of those components and whether the economic and regulatory characteristics are similar. We determined that our reporting units are equivalent to our reportable segments, except for the reporting units of our Western Canada Transmission & Processing and Spectra Energy Partners reportable segments, which are one level below. As permitted under accounting guidance on testing goodwill for impairment, we perform either a qualitative assessment or a quantitative assessment of each of our reporting units based on management’s judgment. With respect to our qualitative assessments, we consider events and circumstances specific to us, such as macroeconomic conditions, industry and market considerations, cost factors and overall financial performance, when evaluating whether it is more likely than not that the fair values of our reporting units are less than their respective carrying amounts. In connection with our quantitative assessments, we primarily use a discounted cash flow analysis to determine the fair values of those reporting units. Key assumptions in the determination of fair value included the use of an appropriate discount rate and estimated future cash flows. In estimating cash flows, we incorporate expected long-term growth rates in key markets served by our operations, regulatory stability, the ability to renew contracts, commodity prices (where appropriate) and foreign currency exchange rates, as well as other factors that affect our reporting units’ revenue, expense and capital expenditure projections. If the carrying amount of the reporting unit exceeds its fair value, a comparison of the fair value and carrying value of the goodwill of that reporting unit needs to be performed. If the carrying value of the goodwill of a reporting unit exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to the excess. Additional impairment tests are performed between the annual reviews if events or changes in circumstances make it more likely than not that the fair value of a reporting unit is below its carrying amount. Property, Plant and Equipment. Property, plant and equipment is stated at historical cost less accumulated depreciation. We capitalize all construction-related direct labor and material costs, as well as indirect construction costs. Indirect costs include general engineering, taxes and the cost of funds used during construction. The costs of renewals and betterments that extend the useful life or increase the expected output of property, plant and equipment are also capitalized. The costs of repairs, replacements and major maintenance projects that do not extend the useful life or increase the expected output of property, plant and equipment are expensed as incurred. Depreciation is generally computed over the asset’s estimated useful life using the straight-line method. When we retire regulated property, plant and equipment, we charge the original cost plus the cost of retirement, less salvage value, to accumulated depreciation and amortization. When we sell entire regulated operating units or retire non-regulated properties, the cost is removed from the property account and the related accumulated depreciation and amortization accounts are reduced. Any gain or loss is recorded in earnings, unless otherwise required by the applicable regulatory body. Preliminary Project Costs. Project development costs, including expenditures for preliminary surveys, plans, investigations, environmental studies, regulatory applications and other costs incurred for the purpose of determining the feasibility of capital expansion projects, are capitalized for rate-regulated enterprises when it is determined that recovery of such costs through regulated revenues of the completed project is probable. Any inception-to-date costs of the project that were initially expensed are reversed and capitalized as Property, Plant and Equipment. Long-Lived Asset Impairments. We evaluate whether long-lived assets, excluding goodwill, have been impaired when circumstances indicate the carrying value of those assets may not be recoverable. For such long-lived assets, an impairment exists when its carrying value exceeds the sum of estimates of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. When alternative courses of action to recover the carrying amount of a long-lived asset are under consideration, a probability-weighted approach is used in developing estimates of future undiscounted cash flows. If the carrying value of the long-lived asset is not recoverable based on these estimated future undiscounted cash flows, an impairment loss is measured as the excess of the asset’s carrying value over its fair value, such that the asset’s carrying value is adjusted to its estimated fair value. We assess the fair value of long-lived assets using commonly accepted techniques and may use more than one source. Sources to determine fair value include, but are not limited to, recent third-party comparable sales, internally developed discounted cash flow analyses and analyses from outside advisors. Significant changes in market conditions resulting from events such as changes in natural gas available to our systems, the condition of an asset, a change in our intent to utilize the asset or a significant change in contracted revenues or regulatory recoveries would generally require us to reassess the cash flows related to the long-lived assets. Asset Retirement Obligations. We recognize asset retirement obligations (AROs) for legal commitments associated with the retirement of long-lived assets that result from the acquisition, construction, development and/or normal use of the asset and conditional AROs in which the timing or method of settlement are conditional on a future event that may or may not be within our control. The fair value of a liability for an ARO is recognized in the period in which it is incurred if a reasonable estimate of fair value can be made and is added to the carrying amount of the associated asset. This additional carrying amount is depreciated over the estimated useful life of the asset. Unamortized Debt Premium, Discount and Expense. Premiums, discounts and expenses incurred with the issuance of outstanding long-term debt are amortized over the terms of the debt issues. Any call premiums or unamortized expenses associated with refinancing higher-cost debt obligations to finance regulated assets and operations are amortized consistent with regulatory treatment of those items, where appropriate. Environmental Expenditures. We expense environmental expenditures related to conditions caused by past operations that do not generate current or future revenues. Environmental expenditures related to operations that generate current or future revenues are expensed or capitalized, as appropriate. Undiscounted liabilities are recorded when the necessity for environmental remediation becomes probable and the costs can be reasonably estimated, or when other potential environmental liabilities are reasonably estimable and probable. Captive Insurance Reserves. We have captive insurance subsidiaries which provide insurance coverage to our consolidated subsidiaries as well as certain equity affiliates, on a limited basis, for various business risks and losses, such as workers compensation, property, business interruption and general liability. Liabilities include provisions for estimated losses incurred but not yet reported, as well as provisions for known claims which have been estimated on a claims-incurred basis. Incurred but not yet reported reserve estimates involve the use of assumptions and are based upon historical loss experience, industry data and other actuarial assumptions. Reserve estimates are adjusted in future periods as actual losses differ from historical experience. Guarantees. Upon issuance or material modification of a guarantee made by us, we recognize a liability for the estimated fair value of the obligation we assume under that guarantee, if any. Fair value is estimated using a probability-weighted approach. We reduce the obligation over the term of the guarantee or related contract in a systematic and rational method as risk is reduced under the obligation. Accounting For Sales of Stock by a Subsidiary. Sales of stock by a consolidated subsidiary are accounted for as equity transactions in those instances where a change in control does not take place. Segment Reporting. Operating segments are components of an enterprise for which separate financial information is available and evaluated regularly by the chief operating decision maker (CODM) in deciding how to allocate resources and evaluate performance. Two or more operating segments may be aggregated into a single reportable segment provided certain criteria are met. There is no such aggregation within our defined business segments. A description of our reportable segments, consistent with how business results are reported internally to management, and the disclosure of segment information is presented in Note 4. Consolidated Statements of Cash Flows. Cash flows from discontinued operations are combined with cash flows from continuing operations within operating, investing and financing cash flows. Cash received from insurance proceeds are classified depending on the activity that resulted in the insurance proceeds. For example, business interruption insurance proceeds are included as a component of operating activities while insurance proceeds from damaged property are included as a component of investing activities. With respect to cash overdrafts, book overdrafts are included within operating cash flows while bank overdrafts, if any, are included within financing cash flows. Distributions from Equity Investments. We consider distributions received from equity investments which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and classify these amounts as Cash Flows From Operating Activities within the accompanying Consolidated Statements of Cash Flows. Cumulative distributions received in excess of cumulative equity in earnings subsequent to the date of investment are considered to be a return of investment and are classified as Cash Flows From Investing Activities. New Accounting Pronouncements. The following Accounting Standards Updates (ASUs) were adopted during 2016 and the effect of such adoption has been presented in the accompanying Consolidated Financial Statements: In June 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-10, “Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation , ” which amends the consolidation guidance around reporting entities that invest in development stage entities. We adopted the consolidation guidance of this amendment on January 1, 2016 and applied it retrospectively with no material effect on our consolidated results of operations, financial position or cash flows. This ASU resulted in certain of our entities being classified as Variable Interest Entities (VIEs). See Note 11 for discussion of our VIEs. In February 2015, the FASB issued ASU No. 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis,” which makes changes to both the variable interest model and the voting model. These changes required reevaluation of certain entities for consolidation and required us to revise our documentation regarding the consolidation or deconsolidation of such entities. We adopted this standard on January 1, 2016 with no material effect on our consolidated results of operations, financial position or cash flows. In September 2015, the FASB issued ASU No. 2015-16, “Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments , ” to simplify accounting for adjustments made to provisional amounts recognized in a business combination and to eliminate the retrospective accounting for those adjustments. We adopted this standard on January 1, 2016. The adoption of this standard did not have a material impact on our consolidated results of operations, financial position or cash flows. Pending. The following ASUs have been issued but not yet adopted: In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” in an effort to improve revenue recognition practices across entities and industries. The ASU introduces a single, principles-based revenue recognition model which centers on the core principle of an entity recognizing revenue in a manner that depicts the transfer of goods and services to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Since its release, the FASB has issued multiple amendments clarifying and/or amending ASU No. 2014-09. We have substantially completed a review of contracts with customers in relation to the requirements of ASU No. 2014-09. While we have not identified any material difference in the amount or timing of revenue recognition for the categories we have reviewed to date, our evaluation is not complete and we have not concluded on the overall impacts of adopting this standard. In addition, we are in the process of implementing appropriate changes to our business processes, systems and controls to support the recognition and disclosure requirements under the new standard. ASU No. 2014-09 is effective for us on January 1, 2018 and allows for either full retrospective or modified retrospective adoption. In July 2015, the FASB issued ASU No. 2015-11, “Inventory (Topic 330): Simplifying the Measurement of Inventory,” which simplifies the subsequent measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. This ASU is effective for us January 1, 2017 and is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments—Overall (Topic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities,” which amends the classification and measurement of financial instruments. Changes primarily affect the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. This ASU is effective for us on January 1, 2018. Early adoption is not permitted. We are currently evaluating this ASU and its potential impact on us. In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842),” to improve the financial reporting around leasing transactions. The new guidance requires companies to begin recording assets and liabilities arising from those leases classified as operating leases under previous guidance. Furthermore, the new guidance will require significant additional disclosures about the amount, timing and uncertainty of cash flows from leases. Topic 842 retains a distinction between finance leases and operating leases. The classification criteria for distinguishing between finance leases and operating leases are substantially similar to the classification criteria for distinguishing between capital leases and operating leases in previous guidance. The result of retaining a distinction between finance leases and operating leases is that under the

Spectra Energy Partners, LP

Spectra Energy Partners, LP	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Spectra Energy Partners, LP	Spectra Energy Partners, LP SEP is our natural gas infrastructure and crude oil pipeline master limited partnership. As of December 31, 2016 , Spectra Energy owned 75% of SEP, including a 2% general partner interest. Sand Hills and Southern Hills. In October 2015, Spectra Energy acquired SEP’s 33.3% ownership interests in DCP Sand Hills Pipeline, LLC (Sand Hills) and DCP Southern Hills Pipeline, LLC (Southern Hills). In consideration for this transaction, SEP retired 21,560,000 of our limited partner units and 440,000 of our general partner units in SEP. This resulted in the reduction of any associated distribution payable to us, effective in 2016. There will also be a reduction in the aggregate quarterly distributions, if any, to us (as holder of incentive distribution rights), by $4 million per quarter for a period of 12 consecutive quarters, which commenced with the quarter ending on December 31, 2015 and will end with the quarter ending on September 30, 2018. The total reduction of distributions to us from SEP was $16 million for the year ended December 31, 2016. U.S. Assets Dropdown. During 2013, Spectra Energy contributed substantially all of its interests in its subsidiaries that own U.S. transmission and storage and liquids assets and assigned them to SEP (collectively, the U.S. Assets Dropdown), excluding a 25.05% ownership interest in Southeast Supply Header, LLC (SESH) and a 1% ownership interest in Steckman Ridge, LP (Steckman Ridge). This was the first of three planned transactions. In 2014, we completed the second of the three planned transactions related to the U.S Assets Dropdown. This transaction consisted of contributing an additional 24.95% ownership interest in SESH and the remaining 1% interest in Steckman Ridge to SEP. Consideration to Spectra Energy was approximately 4.3 million newly issued SEP common units. Also, in connection with this transaction, SEP issued approximately 86,000 of newly issued general partner units to Spectra Energy in exchange for the same amount of common units in order to maintain Spectra Energy’s 2% general partner interest in SEP. The third, and final, transaction related to the U.S. Assets Dropdown occurred in November 2015. It consisted of Spectra Energy’s contribution of the remaining 0.1% interest in SESH to SEP. Total consideration for the third transaction to Spectra Energy was 17,114 newly issued SEP common units. Also, in connection with this third transaction, SEP issued 342 general partner units to Spectra Energy in exchange for the same amount of common units in order to maintain Spectra Energy’s 2% general partner interest in SEP. Sales of SEP Common Units. SEP has entered into equity distribution agreements for its at-the-market offering program, pursuant to which SEP may offer and sell, through sales agents, common units representing limited partner interests at prices it deems appropriate having aggregate offering prices ranging from $400 million to up to $1 billion . Sales of common units, if any, will be made by means of ordinary brokers’ transactions on the New York Stock Exchange (NYSE), in block transactions, or as otherwise agreed to between SEP and the sales agent. SEP intends to use the net proceeds from sales under the program for general partnership purposes, which may include debt repayment, future acquisitions and capital expenditures. Under this program SEP issued 12.8 million , 12.0 million and 6.4 million common units to the public in 2016 , 2015 and 2014 , respectively, for total net proceeds of $579 million , $546 million and $327 million , respectively. In 2016 , 2015 and 2014 , SEP also issued 262,000 , 245,000 and 132,000 general partner units, respectively, to Spectra Energy. In April 2016, SEP issued 10.4 million common units and 0.2 million general partner units to Spectra Energy in a private placement transaction. See Note 23 for further discussion.

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions Acquisitions. We consolidate assets and liabilities from acquisitions as of the purchase date and include earnings from acquisitions in consolidated earnings after the purchase date. Assets acquired and liabilities assumed are recorded at estimated fair values on the date of acquisition. The purchase price less the estimated fair value of the acquired assets and liabilities meeting the definition of a “business” is recorded as goodwill. The allocation of the purchase price may be adjusted if additional information is received during the allocation period, which generally does not exceed one year from the consummation date. Sand Hills and Southern Hills. In October 2015, Spectra Energy acquired SEP’s 33.3% ownership interests in Sand Hills and Southern Hills. In consideration for this transaction, SEP retired 21,560,000 of our limited partner units and 440,000 of our general partner units in SEP. See Note 2 for further discussion. This transfer of assets between entities under common control resulted in an increase to Additional Paid-in Capital of $166 million and a decrease to Equity-Noncontrolling Interests of $166 million on the Consolidated Balance Sheet in 2015. The change in Equity-Noncontrolling Interests primarily represents the public unitholders’ share of the decrease in SEP’s equity as a result of the retirement of units previously held by us, less the effects of the resulting increase in the public unitholders’ ownership percentage of SEP. Spectra Energy’s ownership in SEP decreased as a result of the transaction. Dispositions. On August 4, 2016, Westcoast completed the sale of its ownership interests in Empress to Plains Midstream Canada ULC. Consideration received by Westcoast in this transaction was approximately $204 million in cash, including approximately $51 million for inventory and working capital. The total consideration is subject to final working capital adjustments, which are expected to be finalized in the first half of 2017. The sale resulted in a pre-tax loss of less than $1 million and a tax benefit of $27 million , which are reflected in Gain (Loss) on Sales of Other Assets and Other, net and Income Tax Expense, respectively, on our Consolidated Statement of Operations for the year ended December 31, 2016. As discussed above, in October 2015, we acquired SEP’s 33.3% ownership interests in Sand Hills and Southern Hills. We immediately contributed our 33.3% interests in Sand Hills and Southern Hills to DCP Midstream. The contribution is reflected as a non-cash transaction in the statement of cash flows. After this contribution, DCP Midstream and DCP Partners, LP (DCP Partners) each hold a direct one-third ownership interest in the two pipelines. The remaining one-third direct ownership interest continues to be held by Phillips 66. In consideration for this transaction, we increased our basis in the net equity of DCP Midstream and retained our 50% ownership interest.

Business Segments

Business Segments	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Business Segments	Business Segments We manage our business in four reportable segments: Spectra Energy Partners, Distribution, Western Canada Transmission & Processing and Field Services. The remainder of our business operations is presented as “Other,” and consists of unallocated corporate costs and employee benefit plan assets and liabilities, 100%-owned captive insurance subsidiaries and other miscellaneous activities. Our CODM regularly reviews financial information about each of these segments in deciding how to allocate resources and evaluate performance. There is no aggregation within our reportable business segments. Spectra Energy’s presentation of its Spectra Energy Partners segment is reflective of the parent-level focus by our CODM, considering the resource allocation and governance provisions associated with SEP’s master limited partnership structure. SEP maintains a capital and cash management structure that is separate from Spectra Energy’s, is self-funding and maintains its own lines of bank credit and cash management accounts. From a Spectra Energy perspective, our CODM evaluates the Spectra Energy Partners segment as a whole, without regard to any of SEP’s individual businesses. Spectra Energy Partners provides transmission, storage and gathering of natural gas, as well as the transportation of crude oil through interstate pipeline systems for customers in various regions of the midwestern, northeastern and southern U.S. and Canada. The natural gas transmission and storage operations are primarily subject to the rules and regulations of the Federal Energy Regulatory Commission (FERC). The crude oil transportation operations are primarily subject to regulation by the FERC in the U.S. and the National Energy Board (NEB) in Canada. Our Spectra Energy Partners segment is composed of the operations of SEP, less governance costs, which are included in “Other.” Distribution provides retail natural gas distribution service in Ontario, Canada, as well as natural gas transmission and storage services to other utilities and energy market participants. These services are provided by Union Gas Limited (Union Gas), and are primarily subject to the rules and regulations of the OEB. Western Canada Transmission & Processing provides transmission of natural gas and natural gas gathering and processing services to customers in western Canada, the U.S. Pacific Northwest and the Maritime Provinces in Canada. This segment conducts business mostly through BC Pipeline, BC Field Services, Canadian Midstream and Maritimes & Northeast Pipeline Limited Partnership (M&N Canada). BC Pipeline, BC Field Services and M&N Canada operations are primarily subject to the rules and regulations of the NEB. See Note 3 for discussion related to the sale of Empress on August 4, 2016. Field Services gathers, compresses, treats, processes, transports, stores and sells natural gas, produces, fractionates, transports, stores and sells NGLs, recovers and sells condensate, and trades and markets natural gas and NGLs. It conducts operations through DCP Midstream, which is owned 50% by us and 50% by Phillips 66. DCP Midstream gathers raw natural gas through gathering systems connecting to several interstate and intrastate natural gas and NGL pipeline systems, one natural gas storage facility and one NGL storage facility. DCP Midstream operates in a diverse number of regions, including the Permian Basin, Eagle Ford, Niobrara/DJ Basin and the Midcontinent. DCP Partners is a publicly traded master limited partnership, of which DCP Midstream acts as general partner. As of December 31, 2016 , DCP Midstream had an approximate 21% ownership interest in DCP Partners, including DCP Midstream’s limited partner and general partner interests. Our reportable segments offer different products and services and are managed separately as business units. Management evaluates segment performance based on earnings before interest, taxes, depreciation and amortization (EBITDA). Cash, cash equivalents and short-term investments are managed at the parent-company levels, so the associated gains and losses from foreign currency transactions and interest and dividend income are excluded from the segments’ EBITDA. Our segment EBITDA may not be comparable to similarly titled measures of other companies because other companies may not calculate EBITDA in the same manner. Transactions between reportable segments are accounted for on the same basis as transactions with unaffiliated third parties. Business Segment Data Unaffiliated Revenues Intersegment Revenues Total Operating Revenues Depreciation and Amortization Segment EBITDA/ Consolidated Earnings before Income Taxes Capital and Investment Expenditures Assets (in millions) 2016 Spectra Energy Partners $ 2,533 $ — $ 2,533 $ 316 $ 1,909 $ 2,585 $ 21,813 Distribution 1,370 — 1,370 181 473 788 6,132 Western Canada Transmission & Processing 1,005 15 1,020 227 387 410 6,374 Field Services — — — — (40 ) — 1,621 Total reportable segments 4,908 15 4,923 724 2,729 3,783 35,940 Other 8 63 71 50 (126 ) 91 1,073 Eliminations — (78 ) (78 ) — — — (171 ) Depreciation and amortization — — — — 774 — — Interest expense — — — — 594 — — Interest income and other (a) — — — — 1 — — Total consolidated $ 4,916 $ — $ 4,916 $ 774 $ 1,236 $ 3,874 $ 36,842 2015 Spectra Energy Partners $ 2,455 $ — $ 2,455 $ 297 $ 1,905 $ 2,007 $ 18,983 Distribution 1,527 — 1,527 176 473 544 5,209 Western Canada Transmission & Processing 1,242 43 1,285 243 491 360 5,909 Field Services — — — — (461 ) — 1,660 Total reportable segments 5,224 43 5,267 716 2,408 2,911 31,761 Other 10 63 73 48 (384 ) 61 1,226 Eliminations — (106 ) (106 ) — — — (64 ) Depreciation and amortization — — — — 764 — — Interest expense — — — — 636 — — Interest income and other (a) — — — — (3 ) — — Total consolidated $ 5,234 $ — $ 5,234 $ 764 $ 621 $ 2,972 $ 32,923 2014 Spectra Energy Partners $ 2,269 $ — $ 2,269 $ 290 $ 1,669 $ 1,241 $ 17,850 Distribution 1,843 — 1,843 192 552 427 6,055 Western Canada Transmission & Processing 1,781 121 1,902 271 754 473 6,913 Field Services — — — — 217 — 1,345 Total reportable segments 5,893 121 6,014 753 3,192 2,141 32,163 Other 10 62 72 43 (58 ) 146 1,893 Eliminations — (183 ) (183 ) — — — (58 ) Depreciation and amortization — — — — 796 — — Interest expense — — — — 679 — — Interest income and other (a) — — — — 6 — — Total consolidated $ 5,903 $ — $ 5,903 $ 796 $ 1,665 $ 2,287 $ 33,998 __________ (a) Includes foreign currency transaction gains and losses related to segment EBITDA. Geographic Data U.S. Canada Consolidated (in millions) 2016 Consolidated revenues $ 2,461 $ 2,455 $ 4,916 Consolidated long-lived assets 20,156 11,997 32,153 2015 Consolidated revenues 2,389 2,845 5,234 Consolidated long-lived assets 17,549 10,979 28,528 2014 Consolidated revenues 2,212 3,691 5,903 Consolidated long-lived assets 15,834 12,715 28,549

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2016
Regulated Operations [Abstract]
Regulatory Matters	Regulatory Matters Regulatory Assets and Liabilities We record assets and liabilities that result from the regulated ratemaking process that would not be recorded under U.S. GAAP for non-regulated entities. See Note 1 for further discussion. The following items are reflected in the consolidated balance sheets. All regulatory assets and liabilities are excluded from rate base unless otherwise noted below. Recovery/Refund Period December 31, 2016 2015 (in millions) Regulatory Assets Under-recovery of fuel costs (c) — $ 6 $ 41 Other — 71 73 Total Regulatory Assets—Current (a) 77 114 Net regulatory asset related to income taxes (d,e) 2 years - remaining life of asset 1,397 1,215 Project development costs (d) Through 2036 9 9 Vacation accrual (d) Various 23 23 Deferred debt expense/premium (d) Various 18 23 Other Various 27 13 Total Regulatory Assets—Non Current (b) 1,474 1,283 Total Regulatory Assets $ 1,551 $ 1,397 Regulatory Liabilities Gas purchase costs (c) — $ 10 $ 48 Other (d) — 66 32 Total Regulatory Liabilities—Current (a) 76 80 Removal costs (d) Exceeds remaining life of asset 293 258 Pipeline rate credit Life of associated liability 23 24 Other (d) Various 42 23 Total Regulatory Liabilities—Non Current (b) 358 305 Total Regulatory Liabilities $ 434 $ 385 ________ (a) Included in Inventory, Fuel Tracker, Current Assets—Other, Taxes Accrued or Current Liabilities—Other. (b) Included in Regulatory Assets and Deferred Debits or Deferred Credits and Other Liabilities—Regulatory and Other. (c) Includes costs settled in cash annually through gas commodity and transportation rates in accordance with FERC and/or OEB gas tariffs. (d) All or a portion of the balance is included in rate base. (e) All amounts are expected to be included in future rate filings. Union Gas. Union Gas has regulatory assets of $344 million as of December 31, 2016 and $291 million as of December 31, 2015 related to deferred income tax liabilities. Under the current OEB-authorized rate structure, income tax costs are recovered in rates based on the current income tax payable and do not include accruals for deferred income tax. However, as income taxes become payable as a result of the reversal of timing differences that created the deferred income taxes, it is expected that rates will be adjusted to recover these taxes. Since substantially all of these timing differences are related to property, plant and equipment costs, recovery of these regulatory assets is expected to occur over the life of those assets. Union Gas has regulatory liabilities associated with plant removal costs of $293 million as of December 31, 2016 and $258 million as of December 31, 2015 . These regulatory liabilities represent collections from customers under approved rates for future asset removal activities that are expected to occur associated with its regulated facilities. In addition, Union Gas has regulatory liabilities of $10 million as of December 31, 2016 and $48 million as of December 31, 2015 representing gas cost collections from customers under approved rates that vary from actual cost of gas for the associated periods. Union Gas files an application quarterly with the OEB to ensure that customers’ rates are updated to reflect published forward-market prices. The difference between the approved and the actual cost of gas is deferred for future repayment to or refund from customers. BC Pipeline and BC Field Services. The BC Pipeline and BC Field Services businesses in western Canada have regulatory assets of $789 million as of December 31, 2016 and $727 million as of December 31, 2015 related to deferred income tax liabilities. Under the current NEB-authorized rate structure, income tax costs are recovered in tolls based on the current income tax payable and do not include accruals for deferred income tax. However, as income taxes become payable as a result of the reversal of timing differences that created the deferred income taxes, it is expected that transportation and field services tolls will be adjusted to recover these taxes. Since most of these timing differences are related to property, plant and equipment costs, this recovery is expected to occur over the life of those assets. When evaluating the recoverability of the BC Pipelines’ and BC Field Services’ regulatory assets, we take into consideration the NEB regulatory environment, natural gas reserve estimates for reserves located or expected to be located near these assets, the ability to remain competitive in the markets served and projected demand growth estimates for the areas served by the BC Pipeline and BC Field Services businesses. Based on current evaluation of these factors, we believe that recovery of these tax costs is probable over the periods described above. Rate Related Information Union Gas. In June 2016, a decision from the OEB was received approving recovery of the 2014 Demand Side Management (DSM) deferral and variance account balances from ratepayers. Union Gas began recovery of approximately $9 million from customers on October 1, 2016. In March 2016, Union Gas filed a Draft Rate Order with the OEB for rates effective January 1, 2016 based on the OEB’s February 24, 2016 updated Decision and Order on the 2015-2020 DSM Plan. In May 2016, a decision from the OEB was received approving recovery from ratepayers of approximately $19 million effective January 1, 2016 with an implementation date of July 1, 2016. As part of Union Gas’ 2017 rates application, Union Gas has included an approved DSM budget of approximately $43 million in 2017 rates. The 2017 budget was approved as part of the OEB Revised Decision in the 2015-2020 DSM Plan proceeding. In April 2016, Union Gas filed an application with the OEB for the annual disposition of the 2015 deferral account balances. As a result, Union Gas had a net receivable from customers of approximately $18 million . In August 2016, a decision from the OEB was received approving recovery from ratepayers which began October 1, 2016.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income Tax Expense Components 2016 2015 2014 (in millions) Current income taxes Federal $ (1 ) $ — $ 1 State (8 ) 13 3 Foreign 27 60 (10 ) Total current income taxes 18 73 (6 ) Deferred income taxes Federal 258 145 335 State (20 ) (18 ) (17 ) Foreign (40 ) (39 ) 70 Total deferred income taxes 198 88 388 Total income tax expense $ 216 $ 161 $ 382 Earnings before Income Taxes 2016 2015 2014 (in millions) Domestic $ 1,010 $ 636 $ 1,108 Foreign 226 (15 ) 557 Total earnings before income taxes $ 1,236 $ 621 $ 1,665 Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to Actual Income Tax Expense 2016 2015 2014 (in millions) Income tax expense, computed at the statutory rate of 35% $ 433 $ 217 $ 583 State income tax, net of federal income tax effect 17 12 25 Tax differential on foreign earnings (71 ) (44 ) (125 ) Noncontrolling interests (114 ) (92 ) (70 ) Valuation allowance (11 ) 1 2 Goodwill impairment — 91 — Revaluation of accumulated deferred state taxes (18 ) (12 ) (25 ) Other items, net (20 ) (12 ) (8 ) Total income tax expense $ 216 $ 161 $ 382 Effective tax rate 17.5 % 25.9 % 22.9 % Net Deferred Income Tax Liability Components December 31, 2016 2015 (in millions) Deferred credits and other liabilities $ 279 $ 275 Net operating loss carryforward 256 295 Other 45 36 Total deferred income tax assets 580 606 Valuation allowance (16 ) (27 ) Net deferred income tax assets 564 579 Investments and other assets (1,516 ) (1,605 ) Accelerated depreciation rates (4,428 ) (4,035 ) Regulatory assets and deferred debits (389 ) (384 ) Total deferred income tax liabilities (6,333 ) (6,024 ) Total net deferred income tax liabilities (a) $ (5,769 ) $ (5,445 ) ________ (a) These amounts are classified as Deferred Credits and Other Liabilities—Deferred Income Taxes in the Consolidated Balance Sheets. At December 31, 2016 , we had a federal net operating loss carryforward, net of unrecognized tax benefits, of $572 million that expires at various times beginning in 2021 . The deferred tax asset attributable to the federal net operating loss, net of unrecognized tax benefits, is $200 million . We had valuation allowances of $9 million at both December 31, 2016 and 2015 against the deferred tax asset related to the federal net operating loss carryforward. At December 31, 2016 , we had a state net operating loss carryforward, net of unrecognized tax benefits, of approximately $399 million that expires at various times beginning in 2020 . The deferred tax asset attributable to the state net operating loss carryforward, net of federal impacts and unrecognized tax benefits, is $20 million . We had a valuation allowance of $1 million at December 31, 2015 against the deferred tax asset related to the state net operating loss carryforward and other state tax credits. At December 31, 2016 , we had a federal and state capital loss carryforward of $77 million that expires in 2021 . The federal deferred tax asset attributable to the capital loss carryforward is $27 million and the state deferred tax asset attributable to the capital loss carryforward is $1 million , net of federal impacts. At December 31, 2016 , we had foreign net operating loss carryforwards of $135 million that expires at various times beginning in 2026 . The deferred tax asset attributable to the foreign net operating losses is $36 million . We had valuation allowances of $1 million at both December 31, 2016 and 2015 against the deferred tax asset related to the foreign net operating loss carryforwards. At December 31, 2016 , we also had a foreign capital loss carryforward of $48 million with an indefinite expiration period. The deferred tax asset attributable to the foreign capital loss carryforward is $6 million . We had valuation allowances of $6 million and $16 million at December 31, 2016 and 2015 , respectively, against the deferred tax asset related to the foreign capital loss carryforward. Reconciliation of Gross Unrecognized Income Tax Benefits 2016 2015 2014 (in millions) Balance at beginning of period $ 82 $ 50 $ 76 Increases related to prior year tax positions 15 10 10 Decreases related to prior year tax positions (2 ) (1 ) (6 ) Increases related to current year tax positions 1 30 1 Lapse of statute of limitations (22 ) (4 ) (30 ) Foreign currency translation 1 (3 ) (1 ) Balance at end of period $ 75 $ 82 $ 50 Unrecognized tax benefits totaled $75 million at December 31, 2016 . Of this, $45 million would reduce the annual effective tax rate if recognized on or after January 1, 2017. We recorded a net decrease of $7 million in gross unrecognized tax benefits during 2016 . This was a result of $6 million attributable to deferred tax liabilities, foreign currency exchange rate fluctuations and a $1 million decrease in income tax expense. We recognize potential accrued interest and penalties related to unrecognized tax benefits as interest expense and as other expense, respectively. We recognized interest income of $17 million in 2016 and interest expense of $2 million in 2015 related to unrecognized tax benefits. Accrued interest and penalties totaled $4 million at December 31, 2016 and $21 million at December 31, 2015 . Although uncertain, we believe it is reasonably possible that the total amount of unrecognized tax benefits could decrease by $20 million to $30 million prior to December 31, 2017 due to audit settlements and statute of limitations expirations. We remain subject to examination for Canada income tax return filings for years 2009 through 2015 and U.S. federal income tax return filings for years 2013 through 2015 . A limited number of state tax return filings remain subject to examination for years 2007 through 2015 . We have foreign subsidiaries’ undistributed earnings of approximately $1.8 billion at December 31, 2016 that are indefinitely invested outside the U.S. and, accordingly, no U.S. federal or state income taxes have been provided on those earnings. Upon distribution of those earnings, we may be subject to both foreign withholding taxes and U.S. income taxes, net of allowable foreign tax credits. The amount of such additional taxes would be dependent on several factors, including the size and timing of the distribution and the availability of foreign tax credits. As a result, the determination of the potential amount of unrecognized withholding and deferred income taxes is not practicable.

Earnings per Common Share

Earnings per Common Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common Share Basic earnings per common share (EPS) is computed by dividing net income from controlling interests by the weighted-average number of common shares outstanding during the period. Diluted EPS is computed by dividing net income from controlling interests by the diluted weighted-average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if securities or other agreements to issue common stock, such as stock options, stock-based performance unit awards and phantom stock awards, were exercised, settled or converted into common stock. Weighted-average shares used to calculate diluted EPS includes the effect of certain options and restricted stock awards. In 2016, 2015 and 2014, there were no options or stock awards that were not included in the calculation of diluted EPS. The following table presents our basic and diluted EPS calculations: 2016 2015 2014 (in millions, except per-share amounts) Net income—controlling interests $ 693 $ 196 $ 1,082 Weighted-average common shares outstanding Basic 694 671 671 Diluted 696 672 672 Basic and diluted earnings per common share $ 1.00 $ 0.29 $ 1.61

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income	12 Months Ended
	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following table presents the net of tax changes in AOCI by component, excluding amounts attributable to noncontrolling interests: Foreign Currency Translation Adjustments Pension and Post-retirement Benefit Plan Obligations Gas Purchase Contract Hedges Other Total Accumulated Other Comprehensive Income (Loss) (in millions) December 31, 2014 $ 1,016 $ (351 ) $ (3 ) $ — $ 662 Other AOCI activity (937 ) 5 — 1 (931 ) December 31, 2015 79 (346 ) (3 ) 1 (269 ) Other AOCI activity 147 (24 ) 3 (3 ) 123 December 31, 2016 $ 226 $ (370 ) $ — $ (2 ) $ (146 )

Inventory

Inventory	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventory	Inventory The components of inventory are as follows: December 31, 2016 2015 (in millions) Natural gas $ 183 $ 217 NGLs — 23 Materials and supplies 70 67 Total inventory $ 253 $ 307 NGL inventory previously held at our Empress operations at Western Canada Transmission & Processing was subject to lower of cost or market. As such, we recorded non-cash charges totaling $14 million in 2015 ( $10 million after tax) to Natural Gas and Petroleum Products Purchased on the Consolidated Statement of Operations to reduce propane inventory to estimated net realizable value. Empress was sold on August 4, 2016. See Note 3 for further discussion related to the sale of Empress.

Investments in and Loans to Unc

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions	12 Months Ended
	Dec. 31, 2016
Investments in and Advances to Affiliates, Schedule of Investments [Abstract]
Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions	Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions Investments in affiliates for which we are not the primary beneficiary, but over which we have significant influence, are accounted for using the equity method. As of December 31, 2016 and 2015 , the carrying amounts of investments in affiliates approximated the amounts of underlying equity in net assets, with the exception of DCP Midstream, which relates to a contribution of assets recorded at carrying value in 2015. We received distributions from our equity investments of $161 million in 2016 , $612 million in 2015 and $646 million in 2014 . Cumulative undistributed earnings of unconsolidated affiliates totaled $33 million at December 31, 2016 and $28 million at December 31, 2015 . Spectra Energy Partners. As of December 31, 2016 , our Spectra Energy Partners segment investments were mostly comprised of a 39% effective interest in Gulfstream Natural Gas System, LLC (Gulfstream), a 39% effective interest in SESH and a 39% effective interest in Steckman Ridge. In November 2015, we contributed our remaining 0.1% interest in SESH to SEP. Total consideration to Spectra Energy was 17,114 newly issued SEP common units. This was the last of three planned transactions related to the U.S. Assets Dropdown. Also, in connection with this transaction, SEP issued 342 general partner units to Spectra Energy in exchange for the same amount of common units in order to maintain Spectra Energy’s 2% general partner interest in SEP. We have a loan outstanding to Steckman Ridge in connection with the construction of its storage facilities. The loan carries market-based interest rates and is due the earlier of October 1, 2023 or coincident with the closing of any long-term financings by Steckman Ridge. The loan receivable from Steckman Ridge, including accrued interest, totaled $71 million at December 31, 2016 and 2015 . We recorded interest income on the Steckman Ridge loan of $1 million in 2016 , 2015 and 2014 . In October 2015, Spectra Energy acquired SEP’s 33.3% ownership interests in Sand Hills and Southern Hills. In consideration for this transaction, SEP retired 21,560,000 of our limited partner units and 440,000 of our general partner units in SEP. This resulted in the reduction of any associated distribution payable to us, effective in 2016. There will also be a reduction in the aggregate quarterly distributions, if any, to us (as holder of incentive distribution rights), by $4 million per quarter for a period of 12 consecutive quarters, which commenced with the quarter ending on December 31, 2015 and will end with the quarter ending on September 30, 2018. The total reduction of distributions to us from SEP was $16 million for the year ended December 31, 2016. Field Services. Our most significant investment in unconsolidated affiliates is our 50% investment in DCP Midstream, which is accounted for under the equity method of accounting. DCP Midstream is a limited liability company which is a pass-through entity for U.S. income tax purposes. We recognize the tax effects of our share of DCP Midstream’s pass-through earnings in Income Tax Expense in the Consolidated Statements of Operations. DCP Partners issues, from time to time, limited partner units to the public, which are recorded by DCP Midstream directly to its equity. Our proportionate 50% share of gains from those issuances, totaling $2 million in 2015 and $73 million in 2014 , are reflected in Earnings (Loss) from Equity Investments in the Consolidated Statements of Operations. There were no material gains from issuances in 2016 . DCP Midstream performed a goodwill impairment test and other asset impairment tests in 2015. The impairment tests resulted in DCP Midstream’s recognition of a $460 million goodwill impairment and $342 million in other asset impairments, net of tax, which reduced our equity earnings from DCP Midstream by $231 million after-tax for 2015. As previously discussed, in October 2015, we contributed our 33.3% interests in Sand Hills and Southern Hills acquired from SEP to DCP Midstream. In consideration for this transaction, we increased our basis in the net equity of DCP Midstream and retained our 50% ownership interest. Investments in and Loans to Unconsolidated Affiliates December 31, 2016 December 31, 2015 Domestic International Total Domestic International Total (in millions) Spectra Energy Partners $ 1,127 $ — $ 1,127 $ 904 $ — $ 904 Distribution — 11 11 — 11 11 Western Canada Transmission & Processing — 21 21 — 17 17 Field Services 1,621 — 1,621 1,660 — 1,660 Total $ 2,748 $ 32 $ 2,780 $ 2,564 $ 28 $ 2,592 Equity in Earnings of Unconsolidated Affiliates 2016 2015 2014 Domestic International Total Domestic International Total Domestic International Total (in millions) Spectra Energy Partners $ 134 $ — $ 134 $ 167 $ — $ 167 $ 133 $ — $ 133 Distribution — 1 1 — 1 1 — 1 1 Western Canada Transmission & Processing — 3 3 — 2 2 — 1 1 Field Services (41 ) — (41 ) (461 ) — (461 ) 217 — 217 Other — — — 1 — 1 9 — 9 Total $ 93 $ 4 $ 97 $ (293 ) $ 3 $ (290 ) $ 359 $ 2 $ 361 Summarized Combined Financial Information of Unconsolidated Affiliates (Presented at 100%) Statements of Operations 2016 2015 2014 DCP Midstream Other Total DCP Midstream Other Total DCP Midstream Other Total (in millions) Operating revenues $ 6,937 $ 494 $ 7,431 $ 7,420 $ 767 $ 8,187 $ 14,013 $ 744 $ 14,757 Operating expenses 6,771 176 6,947 8,227 288 8,515 13,262 319 13,581 Operating income (loss) 166 318 484 (807 ) 479 (328 ) 751 425 1,176 Net income (loss) 81 260 341 (843 ) 393 (450 ) 536 332 868 Net income (loss) attributable to members’ interests (75 ) 260 185 (929 ) 393 (536 ) 288 332 620 Balance Sheets December 31, 2016 December 31, 2015 DCP Midstream Other Total DCP Midstream Other Total (in millions) Current assets $ 1,484 $ 191 $ 1,675 $ 800 $ 498 $ 1,298 Non-current assets 12,610 3,824 16,434 13,094 3,265 16,359 Current liabilities (1,646 ) (126 ) (1,772 ) (896 ) (387 ) (1,283 ) Non-current liabilities (5,554 ) (1,680 ) (7,234 ) (5,894 ) (1,679 ) (7,573 ) Equity—total 6,894 2,209 9,103 7,104 1,697 8,801 Equity—noncontrolling interests (2,270 ) — (2,270 ) (2,404 ) — (2,404 ) Equity—controlling interests $ 4,624 $ 2,209 $ 6,833 $ 4,700 $ 1,697 $ 6,397 Related Party Transactions DCP Midstream . DCP Midstream processes certain of our pipeline customers’ gas to meet gas quality specifications in order to be transported on our Texas Eastern Transmission, LP (Texas Eastern) system. DCP Midstream processes the gas and sells the NGLs that are extracted from the gas. A portion of the proceeds from those sales are retained by DCP Midstream and the balance is remitted to us. We received proceeds of $31 million in 2016, $46 million in 2015 and $79 million in 2014 from DCP Midstream related to those sales, classified as Operating Revenues—Other in our Consolidated Statements of Operations. In addition to the above, we recorded other revenues from DCP Midstream and its affiliates totaling $2 million in 2016, $3 million in 2015 and $2 million in 2014, classified as Operating Revenues—Other in our Consolidated Statements of Operations. We also recorded other revenues totaling $1 million in 2016, $4 million in 2015 and $7 million in 2014, primarily within Transportation, Storage and Processing of Natural Gas, and $4 million in 2015 and $7 million in 2014 within Sales of Natural Gas Liquids in our Consolidated Statements of Operations. There were no related party sales of natural gas liquids in 2016. We had accounts receivable from DCP Midstream and its affiliates of $3 million at December 31, 2016 and $1 million at December 31, 2015. We received no distributions from DCP Midstream during 2016 or 2015. We received distributions from DCP Midstream of $237 million in 2014, classified as Cash Flows from Operating Activities—Distributions from Equity Investments. Gulfstream . During the third quarter of 2015, Gulfstream issued unsecured debt of $800 million to fund the repayment of its current debt. Gulfstream distributed $396 million , our proportionate share of proceeds, to us, classified as Cash Flows from Investing Activities—Distributions from Equity Investments, of which we contributed $248 million back to Gulfstream in the fourth quarter of 2015 and the remaining $148 million , classified as Cash Flows from Investing Activities—Distribution to Equity Investments, in the second quarter of 2016. SESH. In 2014, SESH issued unsecured debt of $400 million to fund the repayment of its current debt. SESH distributed $200 million , our proportionate share of proceeds, to us, classified as Cash Flows from Investing Activities—Distributions from Equity Investments, of which we contributed $200 million back to SESH during 2014, classified as Cash Flows from Investing Activities—Investments in and Loans to Unconsolidated Affiliates, as the current debt matured. Other. We provide certain administrative and other services to certain other operating entities. We recorded recoveries of costs from these affiliates of $68 million in 2016 , $28 million in 2015 and $38 million in 2014 . We also recorded recoveries of costs associated with a project of $116 million in 2016 and $139 million in 2015. Outstanding receivables from these affiliates totaled $21 million at December 31, 2016 and $11 million at December 31, 2015 . See also Notes 3, 18 and 20 for additional related party information.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2016
Variable Interest Entities [Abstract]
Variable Interest Entities	Variable Interest Entities Sabal Trail. On April 1, 2016, NextEra Energy, Inc. (NextEra) purchased a 9.5% interest in Sabal Trail Transmission, LLC (Sabal Trail) from SEP. Consideration for this transaction consisted of approximately $110 million cash, $102 million of which is classified as Cash Flows from Financing Activities—Contributions from Noncontrolling Interests. See Note 12 for additional information related to this transaction. As of December 31, 2016 , we have an effective 37.6% ownership interest in Sabal Trail through our ownership of SEP. Sabal Trail is a joint venture that is constructing a natural gas pipeline to transport natural gas to Florida. Sabal Trail is a VIE due to insufficient equity at risk to finance its activities. We determined that we are the primary beneficiary because we direct the activities of Sabal Trail that most significantly impact its economic performance and we consolidate Sabal Trail in our financial statements. The current estimate of the total remaining construction cost is approximately $1.2 billion . Valley Crossing. Valley Crossing Pipeline, LLC (Valley Crossing), our wholly-owned subsidiary, is constructing a natural gas pipeline to transport natural gas within Texas. We are the primary beneficiary because we direct the activities of Valley Crossing that most significantly impact its economic performance. Accordingly, we consolidate Valley Crossing in our financial statements. The current estimate of the total remaining construction cost is $1.4 billion . The following table summarizes the assets and liabilities of Sabal Trail and Valley Crossing: Consolidated Balance Sheets Caption December 31, December 31, (in millions) Assets Current assets $ 165 $ 118 Net property, plant and equipment 2,084 773 Regulatory assets and deferred debits 79 25 Total Assets $ 2,328 $ 916 Liabilities and Equity Current liabilities $ 382 $ 84 Equity 1,946 832 Total Liabilities and Equity $ 2,328 $ 916 Nexus. We have an effective 37.6% ownership interest in Nexus Gas Transmission, LLC (Nexus) through our ownership of SEP. Nexus is a joint venture that is constructing a natural gas pipeline from Ohio to Michigan and continuing on to Ontario, Canada. Nexus is a VIE due to insufficient equity at risk to finance its activities. We determined that we are not the primary beneficiary because the power to direct the activities of Nexus that most significantly impact its economic performance is shared. Nexus is accounted for under the equity method of accounting. Our maximum exposure to loss is $1 billion . We have an investment in Nexus of $356 million and $90 million as of December 31, 2016 and December 31, 2015 , respectively, classified as Investments in and Loans to Unconsolidated Affiliates on our Consolidated Balance Sheets. On December 29, 2016, SEP issued performance guarantees to a third party and an affiliate on behalf of Nexus. See Note 22 for further discussion of the guarantee agreement.

Intangible Asset

Intangible Asset	12 Months Ended
	Dec. 31, 2016
Intangible Assets Disclosure [Abstract]
Intangible Assets Disclosure [Text Block]	Intangible Assets During the first quarter of 2016, SEP entered into a project coordination agreement (PCA) with NextEra, Duke Energy Corporation (Duke Energy) and Williams Partners L.P. In accordance with the agreement, payments will be made, based on SEP’s proportional ownership interest in Sabal Trail, as certain milestones of the project are met. During the first quarter of 2016, the first milestone was achieved and paid, consisting of $48 million . On April 1, 2016, NextEra purchased an additional 9.5% interest in Sabal Trail from SEP, reducing SEP’s ownership interest in Sabal Trail to 50% . Upon purchase of the additional ownership interest, NextEra reimbursed SEP $8 million for NextEra’s proportional share of the first milestone payment. During the third quarter of 2016, the second milestone was achieved and paid, consisting of $40 million . The milestone payments are classified as Cash Flows from Investing Activities—Purchase of Intangible, Net. This PCA, in the amount of $80 million as of December 31, 2016 , is an intangible asset and is classified as Investments and Other Assets—Other on our Consolidated Balance Sheet. The intangible asset will be amortized over a period of 25 years beginning at the time of in-service of Sabal Trail, which is expected to occur during the first half of 2017.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The following table presents activity within goodwill on a segment basis: Spectra Energy Partners Distribution Western Canada Transmission & Processing Total (in millions) December 31, 2014 $ 3,244 $ 759 $ 711 $ 4,714 Impairment of goodwill — — (333 ) (333 ) Foreign currency translation (12 ) (110 ) (105 ) (227 ) December 31, 2015 3,232 649 273 4,154 Foreign currency translation 2 17 8 27 December 31, 2016 $ 3,234 $ 666 $ 281 $ 4,181 The following remaining goodwill amounts originating from the acquisition of Westcoast in 2002 are included as segment assets within “Other” in the segment data presented in Note 4: December 31, 2016 2015 (in millions) Distribution $ 664 $ 646 Western Canada Transmission & Processing 252 246 In 2015, we performed additional goodwill impairment testing for BC Field Services and Empress due to the sustained downturn in commodity prices. The impairment test was based on a combination of an income approach and a market approach for which the inputs are classified as Level 3. The impairment test resulted in the recognition of a $270 million goodwill impairment for BC Field Services and a $63 million goodwill impairment for Empress for a total goodwill impairment of $333 million . See Note 10 for discussion related to the 2015 impairment of goodwill recognized by DCP Midstream. No triggering events have occurred with our reporting units since April 1, 2016 (our annual testing date) that would warrant re-testing for goodwill impairment.

Marketable Securities and Restr

Marketable Securities and Restricted Funds	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Marketable Securities and Restricted Funds	Marketable Securities and Restricted Funds We routinely invest excess cash and various restricted balances in securities such as commercial paper, bankers acceptances, corporate debt securities, Canadian equity securities, treasury bills and money market securities in the U.S. and Canada. We do not purchase marketable securities for speculative purposes; therefore we do not have any securities classified as trading securities. While we do not routinely sell marketable securities prior to their scheduled maturity dates, some of our investments may be held and restricted for insurance purposes, capital expenditures and NEB regulatory requirements, so these investments are classified as AFS marketable securities as they may occasionally be sold prior to their scheduled maturity dates due to the unexpected timing of cash needs. Initial investments in securities are classified as purchases of the respective type of securities (AFS marketable securities or HTM marketable securities). Maturities of securities are classified within proceeds from sales and maturities of securities in the Consolidated Statements of Cash Flows. AFS Securities. AFS securities are as follows: Estimated Fair Value December 31, 2016 2015 (in millions) Corporate debt securities (a) $ 8 $ 31 Canadian equity securities (b) 27 — Total available-for-sale securities $ 35 $ 31 ___________________________________ (a) Amounts related to certain construction projects. (b) Amounts related to restricted funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements. Our AFS securities are classified on the Consolidated Balance Sheets as follows: Estimated Fair Value December 31, 2016 2015 (in millions) Restricted funds Investments and other assets—other $ 35 $ 11 Non-restricted funds Current assets—other — 20 Total available-for-sale securities $ 35 $ 31 At December 31, 2016 , the weighted-average contractual maturity of outstanding AFS securities was less than one year . There were no material gross unrealized holding gains or losses associated with investments in AFS securities at December 31, 2016 or 2015 . HTM Securities. HTM securities are as follows: Estimated Fair Value December 31, Description Consolidated Balance Sheets Caption 2016 2015 (in millions) Bankers acceptances Current assets—other $ 20 $ 30 Canadian government securities Current assets—other 23 24 Money market securities Current assets—other 3 3 Canadian government securities Investments and other assets—other 39 50 Bankers acceptances Investments and other assets—other — 12 Total held-to-maturity securities $ 85 $ 119 All of our HTM securities are restricted funds pursuant to certain M&N Canada and Express-Platte (our crude oil pipeline system) debt agreements. The funds restricted for M&N Canada, plus future cash from operations that would otherwise be available for distribution to the partners of M&N Canada, are required to be placed in escrow until the balance in escrow is sufficient to fund all future debt service on the M&N Canada 6.90% senior secured notes. There are sufficient funds held in escrow to fund all future debt service on these M&N Canada notes as of December 31, 2016 . At December 31, 2016 , the weighted-average contractual maturity of outstanding HTM securities was less than one year . There were no material gross unrecognized holding gains or losses associated with investments in HTM securities at December 31, 2016 or 2015 . Other Restricted Funds . In addition to the portions of the AFS and HTM securities that were restricted as described above, we had other restricted funds totaling $27 million at December 31, 2016 and $11 million at December 31, 2015 classified as Current Assets—Other on the Consolidated Balance Sheets. Included in these restricted funds are $11 million at December 31, 2016 of funds received from the province of Ontario related to the Green Investment Fund that is to be distributed to eligible homeowners, based on specific energy conservation initiatives at Union Gas, $12 million and $11 million at December 31, 2016 and December 31, 2015 , respectively, related to additional amounts for insurance and $4 million at December 31, 2016 at M&N Canada pursuant to certain debt agreements. We also had other restricted funds totaling $42 million at December 31, 2016 and $38 million at December 31, 2015 classified as Investments and Other Assets—Other on the Consolidated Balance Sheets. At December 31, 2016 these restricted funds consisted of $17 million related to funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements, $5 million related to certain construction projects, $17 million of funds received from the province of Ontario related to the Green Investment Fund and $3 million at M&N Canada pursuant to certain debt agreements. At December 31, 2015 these restricted funds consisted of $24 million related to funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements and $14 million related to certain construction projects. Changes in restricted balances are presented within Cash Flows from Investing Activities on our Consolidated Statements of Cash Flows. Interest income. Interest income totaled $3 million in 2016 and 2015 and $4 million in 2014 , and is included in Other Income and Expenses, Net on the Consolidated Statements of Operations.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment Estimated Useful Life December 31, 2016 2015 (years) (in millions) Plant Natural gas transmission 13–100 $ 17,421 $ 15,690 Natural gas distribution 25–60 2,880 2,651 Gathering and processing facilities 10–40 4,106 4,178 Natural gas storage 10–122 2,193 2,137 Crude oil transportation and storage 5–75 1,321 1,206 Land rights and rights of way 10–122 642 591 Other buildings and improvements 2–75 142 149 Equipment 3–75 305 301 Vehicles 3–15 103 102 Land — 153 138 Construction in process — 3,499 1,919 Software 3–15 438 439 Other 3–82 352 342 Total property, plant and equipment 33,555 29,843 Total accumulated depreciation (6,925 ) (6,527 ) Total accumulated amortization (422 ) (398 ) Total net property, plant and equipment $ 26,208 $ 22,918 We had no material capital leases at December 31, 2016 or 2015 . Almost 86% of our property, plant and equipment is regulated with estimated useful lives based on rates approved by the applicable regulatory authorities in the U.S. and Canada: the FERC, the NEB and the OEB. Composite weighted-average depreciation rates were 2.66% for 2016 , 2.72% for 2015 and 2.82% for 2014 . Amortization expense of intangible assets totaled $74 million in 2016 , $79 million in 2015 and $74 million in 2014 . Estimated amortization expense for the next five years follows: Estimated Amortization Expense (in millions) 2017 $ 82 2018 80 2019 58 2020 36 2021 27

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Our AROs relate mostly to the legal obligations to disconnect, purge and cap abandoned pipelines, capping of abandoned storage wells, the retirement of certain gathering pipelines and processing facilities, obligations related to right-of-way agreements and contractual leases for land use and in some buildings, special handling and disposition of asbestos if it is disturbed. However, we have determined that a significant portion of our assets have an indeterminate life, and as such, the fair values of those associated retirement obligations are not reasonably estimable. These assets include onshore and some offshore pipelines, and certain processing plants and distribution facilities, whose retirement dates will depend mostly on the various natural gas supply sources that connect to our systems and the ongoing demand for natural gas usage in the markets we serve. We expect these supply sources and market demands to continue for the foreseeable future, therefore we are unable to estimate retirement dates that would result in asset retirement obligations. AROs are adjusted each period for liabilities incurred or settled during the period, accretion expense, any revisions made to the estimated cash flows and dispositions of businesses. In 2015, SEP revised the estimated future cash flow assumptions for its ARO liabilities due to a reduction in the remaining estimated life of certain Texas Eastern offshore facilities which resulted in an increase to ARO liabilities of $32 million . Reconciliation of Changes in Asset Retirement Obligation Liabilities 2016 2015 (in millions) Balance at beginning of year $ 418 $ 400 Accretion expense 20 17 Revisions in estimated cash flows (32 ) 72 Asset dispositions (6 ) — Foreign currency exchange impact 11 (62 ) Liabilities settled (6 ) (9 ) Balance at end of year (a) $ 405 $ 418 ________ (a) Amounts included in Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets.

Debt and Credit Facilities

Debt and Credit Facilities	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Debt and Credit Facilities	Debt and Credit Facilities Summary of Debt and Related Terms December 31, 2016 2015 Spectra Energy Capital, LLC (in millions) 6.20% senior unsecured notes due April 2018 $ 500 $ 500 6.75% senior unsecured notes due July 2018 150 150 Variable-rate senior unsecured term loan due November 2018 300 300 8.00% senior unsecured notes due October 2019 500 500 5.65% senior unsecured notes due March 2020 300 300 3.30% senior unsecured notes due March 2023 650 650 6.75% senior unsecured notes due February 2032 240 240 7.50% senior unsecured notes due September 2038 250 250 Total Spectra Energy Capital, LLC Debt 2,890 2,890 SEP SEP 2.95% senior unsecured notes due June 2016 — 250 SEP 2.95% senior unsecured notes due September 2018 500 500 SEP variable-rate senior unsecured term loan due November 2018 400 400 SEP 4.60% senior unsecured notes due June 2021 250 250 SEP 4.75% senior unsecured notes due March 2024 1,000 1,000 SEP 3.50% senior unsecured notes due March 2025 500 500 SEP 3.375% senior unsecured notes due October 2026 600 — SEP 5.95% senior unsecured notes due September 2043 400 400 SEP 4.50% senior unsecured notes due March 2045 700 500 Texas Eastern 6.00% senior unsecured notes due September 2017 400 400 Texas Eastern 4.125% senior unsecured notes due December 2020 300 300 Texas Eastern 2.80% senior unsecured notes due October 2022 500 500 Texas Eastern 7.00% senior unsecured notes due July 2032 450 450 Algonquin 3.51% senior notes due July 2024 350 350 East Tennessee Natural Gas, LLC 3.10% senior notes due December 2024 200 200 Express-Platte 6.09% senior secured notes due January 2020 110 110 Express-Platte 7.39% subordinated secured notes due 2017 to 2019 12 42 Total SEP Debt 6,672 6,152 Westcoast 3.28% medium-term notes due January 2016 — 181 8.50% debentures due September 2018 112 108 5.60% medium-term notes due January 2019 223 217 9.90% debentures due January 2020 74 72 4.57% medium-term notes due July 2020 186 181 3.883% medium-term notes due October 2021 112 108 3.12% medium-term notes due December 2022 186 181 3.43% medium-term notes due September 2024 260 253 8.85% debentures due July 2025 112 108 8.80% medium-term notes due November 2025 18 18 3.77% medium-term notes due December 2025 223 217 7.30% debentures due December 2026 93 90 6.75% medium-term notes due December 2027 112 108 7.15% medium-term notes due March 2031 149 145 4.791% medium-term notes due October 2041 149 145 M&N Canada 6.90% senior secured notes due 2017 to 2019 58 75 M&N Canada 4.34% senior secured notes due 2017 to 2019 28 47 Other 2 2 Total Westcoast Debt $ 2,097 $ 2,256 December 31, 2016 2015 Union Gas (in millions) 4.64% medium-term notes due June 2016 $ — $ 145 9.70% debentures due November 2017 93 90 5.35% medium-term notes due April 2018 149 145 8.75% debentures due August 2018 93 90 8.65% senior debentures due October 2018 56 54 2.76% medium-term notes due June 2021 149 145 4.85% medium-term notes due April 2022 93 90 3.79% medium-term notes due July 2023 186 181 3.19% medium-term notes due September 2025 149 145 8.65% debentures due November 2025 93 90 2.81% medium-term note debentures due June 2026 186 — 5.46% medium-term notes due September 2036 123 119 6.05% medium-term notes due September 2038 223 216 5.20% medium-term notes due July 2040 186 181 4.88% medium-term notes due June 2041 223 217 4.20% medium-term notes due June 2044 371 361 3.80% medium-term note debentures due June 2046 186 — Total Union Gas Debt 2,559 2,269 Total Long-term debt principal (including current maturities) 14,218 13,567 Change in fair value of debt hedged 10 22 Unamortized debt discount, net (20 ) (22 ) Unamortized capitalized debt issuance costs (50 ) (46 ) Other unamortized items 3 4 Total other non-principal amounts (57 ) (42 ) Commercial paper (a,c) 1,453 1,112 Capital Leases 14 19 Total debt (including capital lease obligations) (b) 15,628 14,656 Current maturities of long-term debt (551 ) (652 ) Commercial paper (a,c) (1,453 ) (1,112 ) Total long-term debt (including capital lease obligations) $ 13,624 $ 12,892 ______ (a) The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015 . (b) As of December 31, 2016 and 2015 , respectively, $4,904 million and $4,681 million of debt was denominated in Canadian dollars. (c) Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015 . Secured Debt. Secured debt, totaling $208 million as of December 31, 2016 , includes project financings for M&N Canada and Express-Platte. Ownership interests in M&N Canada and certain of its accounts, revenues, business contracts and other assets are pledged as collateral. Express-Platte notes payable are secured by the assignment of the Express-Platte transportation receivables and by the Canadian portion of the Express-Platte pipeline system assets. Floating Rate Debt. Debt included approximately $2,153 million of floating-rate debt as of December 31, 2016 and $1,812 million as of December 31, 2015 . The weighted average interest rate of borrowings outstanding that contained floating rates was 1.35% at December 31, 2016 and 1.15% at December 31, 2015 . Annual Maturities December 31, 2016 (in millions) 2017 $ 548 2018 2,290 2019 751 2020 970 2021 510 Thereafter 9,163 Total long-term debt, including current maturities (a) $ 14,232 __________ (a) Excludes commercial paper of $1,453 million . Includes capital leases of $14 million . We have the ability under certain debt facilities to call and repay the obligations prior to scheduled maturities. Therefore, the actual timing of future cash repayments could be materially different than presented above. Available Credit Facilities and Restrictive Debt Covenants Expiration Total Commercial Paper Outstanding at December 31, 2016 Available (in millions) Spectra Energy Capital, LLC Multi-year syndicated (a) 2021 $ 1,000 $ 631 $ 369 364-day syndicated (a) 2017 2,000 — 2,000 SEP (b) 2021 2,500 574 1,926 Westcoast (c) 2021 298 — 298 Union Gas (d) 2021 521 248 273 Total $ 6,319 $ 1,453 $ 4,866 __________________ (a) Revolving credit facilities contain a covenant requiring the Spectra Energy consolidated debt-to-total capitalization ratio, as defined in the agreements, to not exceed 65% . Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 56.3% at December 31, 2016 . (b) Revolving credit facility contains a covenant that requires SEP to maintain a ratio of total Consolidated Indebtedness-to-Consolidated EBITDA, as defined in the agreement, of 5.0 to 1 or less. As of December 31, 2016 , this ratio was 3.8 to 1. (c) U.S. dollar equivalent at December 31, 2016 . The revolving credit facility is 400 million Canadian dollars and contains a covenant that requires the Westcoast non-consolidated debt-to-total capitalization ratio to not exceed 75% . The ratio was 33.2% at December 31, 2016 . (d) U.S. dollar equivalent at December 31, 2016 . The revolving credit facility is 700 million Canadian dollars and contains a covenant that requires the Union Gas debt-to-total capitalization ratio to not exceed 75% and a provision which requires Union Gas to repay all borrowings under the facility for a period of two days during the second quarter of each year. The ratio was 69.0% at December 31, 2016 . On September 29, 2016, we entered into a new one-year, $2 billion credit facility at Spectra Energy Capital, LLC (Spectra Capital), which expires in 2017 . Proceeds from borrowings under the credit facility will be used for general corporate purposes. Amounts borrowed under the credit facility must be repaid following any change in control, including any that results from the proposed merger with Enbridge. On April 29, 2016, we amended the Union Gas and SEP revolving credit agreements. The Union Gas revolving credit facility was increased to 700 million Canadian dollars and the SEP revolving facility was increased to $2.5 billion . The expiration of both facilities was extended, with both facilities expiring in 2021 . On April 29, 2016, we amended the Westcoast and Spectra Capital revolving credit agreements. The expiration of both credit facilities was extended, with both facilities expiring in 2021 . The issuances of commercial paper, letters of credit and revolving borrowings reduce the amounts available under the credit facilities. As of December 31, 2016 , there were no letters of credit issued or revolving borrowings outstanding under the credit facilities. Our credit agreements contain various covenants, including the maintenance of certain financial ratios. Failure to meet those covenants beyond applicable grace periods could result in accelerated due dates and/or termination of the agreements. As of December 31, 2016, we were in compliance with those covenants. In addition, our credit agreements allow for acceleration of payments or termination of the agreements due to nonpayment, or in some cases, due to the acceleration of other significant indebtedness of the borrower or some of its subsidiaries. Our debt and credit agreements do not contain provisions that trigger an acceleration of indebtedness based solely on the occurrence of a material adverse change in our financial condition or results of operations. As noted above, the terms of our Spectra Capital credit agreements require our consolidated debt-to-total capitalization ratio, as defined in the agreement, to be 65% or lower. Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 56.3% at December 31, 2016 . Approximately $8.4 billion of our equity (net assets) was considered restricted at December 31, 2016 , representing the minimum amount of equity required to maintain the 65% consolidated debt-to-total capitalization ratio.

Preferred Stock of Subsidiaries

Preferred Stock of Subsidiaries	12 Months Ended
	Dec. 31, 2016
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock of Subsidiaries	Preferred Stock of Subsidiaries Westcoast and Union Gas have outstanding preferred shares owned by third parties that are generally not redeemable prior to specified redemption dates. On or after those dates, the shares may be redeemed, in whole or in part, for cash at the option of Westcoast and Union Gas, as applicable. The shares are not subject to any sinking fund or mandatory redemption and are not convertible into common shares. As redemption of the shares is not solely within our control, we have classified the preferred stock of subsidiaries as temporary equity on our Consolidated Balance Sheets. Dividends are cumulative and payable quarterly, and are included in Net Income—Noncontrolling Interests in the Consolidated Statements of Operations. Approximately 49.7% of the outstanding preferred shares are redeemable at the option of Westcoast and Union Gas, as applicable. On August 30, 2016, Westcoast issued 12 million Cumulative 5-Year Minimum Rate Reset Redeemable First Preferred Shares, Series 12 for an aggregate principal amount of 300 million Canadian dollars (approximately $229 million as of the issuance date). Net proceeds from the issuance were used to fund capital expenditures and for general corporate purposes. In December 2015, Westcoast issued 4.6 million Cumulative 5-Year Minimum Rate Reset Redeemable First Preferred Shares, Series 10 for an aggregate principle amount of 115 million Canadian dollars (approximately $84 million as of the issuance date). Net proceeds from the issuance were used to fund capital expenditures, to refinance maturing debt obligations and for other corporate purposes.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following presents, for each of the fair value hierarchy levels, assets and liabilities that are measured and recorded at fair value on a recurring basis: Description Consolidated Balance Sheet Caption December 31, 2016 Total Level 1 Level 2 Level 3 (in millions) Corporate debt securities Cash and cash equivalents $ 191 $ — $ 191 $ — Interest rate swaps Current assets—other 1 — 1 — Corporate debt securities Investments and other assets—other 8 — 8 — Interest rate swaps Investments and other assets—other 23 — 23 — Canadian equity securities Investments and other assets—other 27 27 — — Total Assets $ 250 $ 27 $ 223 $ — Description Consolidated Balance Sheet Caption December 31, 2015 Total Level 1 Level 2 Level 3 (in millions) Corporate debt securities Cash and cash equivalents $ 137 $ — $ 137 $ — Corporate debt securities Current assets—other 20 — 20 — Commodity derivatives Current assets—other 36 — — 36 Commodity derivatives Investments and other assets—other 5 — — 5 Corporate debt securities Investments and other assets—other 11 — 11 — Interest rate swaps Investments and other assets—other 37 — 37 — Total Assets $ 246 $ — $ 205 $ 41 The following presents changes in Level 3 assets and liabilities that are measured at fair value on a recurring basis using significant unobservable inputs: 2016 2015 (in millions) Derivative assets Fair value, beginning of period $ 41 $ 78 Total gains (losses): Included in earnings (7 ) 43 Included in other comprehensive income 1 (10 ) Purchases (1 ) (3 ) Settlements (34 ) (67 ) Fair value, end of period $ — $ 41 Unrealized gains (losses) relating to instruments held at the end of the period $ — $ (19 ) Level 1 Level 1 valuations represent quoted unadjusted prices for identical instruments in active markets. Level 2 Valuation Techniques Fair values of our financial instruments that are actively traded in the secondary market, including our long-term debt, are determined based on market-based prices. These valuations may include inputs such as quoted market prices of the exact or similar instruments, broker or dealer quotations, or alternative pricing sources that may include models or matrix pricing tools, with reasonable levels of price transparency. For interest rate swaps, we utilize data obtained from a third-party source for the determination of fair value. Both the future cash flows for the fixed-leg and floating-leg of our swaps are discounted to present value. In addition, credit default swap rates are used to develop the adjustment for credit risk embedded in our positions. We believe that since some of the inputs and assumptions for the calculations of fair value are derived from observable market data, a Level 2 classification is appropriate. Level 3 Valuation Techniques Level 3 valuation techniques include the use of pricing models, discounted cash flow methodologies or similar techniques where at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value required significant management judgment or estimation. As of December 31, 2016 , there are no derivative financial instruments classified as Level 3. Those reported in Level 3 at December 31, 2015 consisted of NGL revenue swap contracts related to the Empress assets in Western Canada Transmission & Processing, which were disposed of on August 4, 2016. See Note 3 for further discussion related to the sale of Empress. As of December 31, 2015 , we reported certain of our NGL basis swaps at fair value using Level 3 inputs due to such derivatives not having observable market prices for substantially the full term of the derivative asset or liability. For valuations that included both observable and unobservable inputs, if the unobservable input was determined to be significant to the overall inputs, the entire valuation was categorized in Level 3. This included derivatives valued using indicative price quotations whose contract length extended into unobservable periods. The fair value of these NGL basis swaps was determined using a discounted cash flow valuation technique based on a forward commodity basis curve. For those derivatives, the primary input to the valuation model was the forward commodity basis curve, which was based on observable or public data sources and extrapolated when observable prices were not available. Financial Instruments The fair values of financial instruments that are recorded and carried at book value are summarized in the following table. Judgment is required in interpreting market data to develop the estimates of fair value. These estimates are not necessarily indicative of the amounts we could have realized in current markets. December 31, 2016 2015 Book Value Approximate Fair Value Book Value Approximate Fair Value (in millions) Note receivable, noncurrent (a) $ 71 $ 71 $ 71 $ 71 Long-term debt, including current maturities (b) 14,218 15,168 13,567 13,891 __________ (a) Included within Investments in and Loans to Unconsolidated Affiliates. (b) Excludes commercial paper, capital leases, unamortized items and fair value hedge carrying value adjustments. The fair value of our long-term debt is determined based on market-based prices as described in the Level 2 valuation technique described above and is classified as Level 2. The fair values of cash and cash equivalents, restricted cash, short-term investments, accounts receivable, notes receivable—noncurrent, accounts payable, commercial paper and short-term money market securities are not materially different from their carrying amounts because of the short-term nature of these instruments or because the stated rates approximate market rates. There were no material adjustments to assets and liabilities measured at fair value on a nonrecurring basis in 2016 . In 2015 , we recorded goodwill impairment charges on BC Field Services and Empress reporting units of $270 million and $63 million , respectively. See Note 13 for further discussion.

Risk Management and Hedging Act

Risk Management and Hedging Activities	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management and Hedging Activities	Risk Management and Hedging Activities We are exposed to the impact of market fluctuations in the prices of NGLs and natural gas purchased as a result of our investment in DCP Midstream and processing operations associated with our U.S. pipeline assets. Exposure to interest rate risk exists as a result of the issuance of variable and fixed-rate debt and commercial paper. We are exposed to foreign currency risk from our Canadian operations. We employ established policies and procedures to manage our risks associated with these market fluctuations, which may include the use of derivatives, mostly around interest rate and commodity exposures. As of April 2016, we ceased entering into new contracts under our Empress risk management program. See Note 3 for further discussion related to the sale of Empress. DCP Midstream manages their direct exposure to market prices separate from Spectra Energy, and utilizes various risk management strategies, including the use of commodity derivatives. Other than the commodity derivatives and interest rate swaps as described below, we did not have any significant derivatives outstanding during the year ended December 31, 2016 . Derivative Portfolio Carrying Value as of December 31, 2016 Maturities in 2017 Maturities in 2018 Maturities in 2019 Maturities in 2020 and Thereafter Total Carrying Value (in millions) Derivatives designated as hedging instruments Interest rate swaps $ 1 $ 8 $ — $ 15 $ 24 Total derivatives designated as hedging instruments 1 8 — 15 24 Total derivative instruments $ 1 $ 8 $ — $ 15 $ 24 These amounts represent the combination of amounts presented as assets for non-cash gains on mark-to-market and hedging transactions on our Consolidated Balance Sheet and do not include any derivative positions of DCP Midstream. See Note 19 for information regarding the presentation of these derivative positions on our Consolidated Balance Sheets. Commodity Derivatives. Prior to the sale of Empress on August 4, 2016, our NGL marketing operations were exposed to market fluctuations in the prices of natural gas and NGLs related to natural gas processing and marketing activities. At December 31, 2016 , we had no commodity mark-to-market derivatives outstanding. At December 31, 2015 , we had commodity mark-to-market derivatives outstanding that had netting or rights of offset arrangements as follows: December 31, 2015 Gross Amounts Gross Amounts Offset Net Amount Presented in the Consolidated Balance Sheets Description (in millions) Assets $ 104 $ 63 $ 41 Liabilities 63 63 — Substantially all of our commodity derivative agreements outstanding at December 31, 2015 had provisions that required collateral to be posted in the amount of the net liability position if one of our credit ratings fell below investment grade. Information regarding the impacts of commodity derivatives on our Consolidated Statements of Operations is as follows: Derivatives Consolidated Statements of Operations Caption 2016 2015 2014 (in millions) Commodity derivatives Sales of natural gas liquids $ 8 $ 40 $ 93 Interest Rate Swaps. Changes in interest rates expose us to risk as a result of our issuance of variable and fixed-rate debt and commercial paper. We manage our interest rate exposure by limiting our variable-rate exposures to percentages of total debt and by monitoring the effects of market changes in interest rates. We also enter into financial derivative instruments, including, but not limited to, interest rate swaps and rate lock agreements to manage and mitigate interest rate risk exposure. For interest rate derivative instruments that are designated and qualify as fair value hedges, the gain or loss on the derivative as well as the offsetting loss or gain on the hedged item attributable to the hedged risk is included in Interest Expense on the Consolidated Statements of Operations. There were no significant amounts of gains or losses, either effective or ineffective, recognized in net income or other comprehensive income in 2016 , 2015 or 2014 . At December 31, 2016 , we had “pay floating—receive fixed” interest rate swaps outstanding with a total notional amount of $2 billion to hedge against changes in the fair value of our fixed-rate debt that arise as a result of changes in market interest rates. These swaps also allow us to transform a portion of the underlying interest payments related to our long-term fixed-rate debt securities into variable-rate interest payments in order to achieve our desired mix of fixed and variable-rate debt. Information about our interest rate swaps that had netting or rights of offset arrangements is as follows: December 31, 2016 December 31, 2015 Gross Amounts Presented in the Consolidated Balance Sheets Amounts Not Offset in the Consolidated Balance Sheets Net Amount Gross Amounts Presented in the Consolidated Balance Sheets Amounts Not Offset in the Consolidated Balance Sheets Net Amount Description (in millions) Assets $ 24 $ — $ 24 $ 37 $ — $ 37 Foreign Currency Risk. We are exposed to foreign currency risk from investments and operations in Canada. To mitigate risks associated with foreign currency fluctuations, contracts may be denominated in or indexed to the U.S. dollar and/or local inflation rates, or investments may be naturally hedged through debt denominated or issued in the foreign currency. To monitor our currency exchange rate risks, we use sensitivity analysis, which measures the effect of devaluation of the Canadian dollar. Credit Risk. Our principal customers for natural gas transmission and crude oil transportation, storage and gathering and processing services are industrial end-users, marketers, exploration and production companies, local distribution companies and utilities located throughout the U.S. and Canada. We have concentrations of receivables from natural gas utilities and their affiliates, industrial customers and marketers throughout these regions, as well as retail distribution customers in Canada. These concentrations of customers may affect our overall credit risk in that risk factors can negatively affect the credit quality of the entire sector. Where exposed to credit risk, we analyze the customers’ financial condition prior to entering into an agreement, establish credit limits and monitor the appropriateness of those limits on an ongoing basis. We also obtain parental guarantees, cash deposits or letters of credit from customers to provide credit support, where appropriate, based on our financial analysis of the customer and the regulatory or contractual terms and conditions applicable to each contract.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies General Insurance We carry, either directly or through our captive insurance companies, insurance coverages consistent with companies engaged in similar commercial operations with similar type properties. Our insurance program includes (1) commercial general and excess liability insurance for liabilities to third parties for bodily injury and property damage resulting from our operations; (2) workers’ compensation liability coverage to required statutory limits; (3) automobile liability insurance for all owned, non-owned and hired vehicles covering liabilities to third parties for bodily injury and property damage; (4) insurance policies in support of the indemnification provisions of our by-laws; and (5) property insurance, including machinery breakdown, on an all-risk-replacement valued basis, onshore business interruption and extra expense. All coverages are subject to certain deductibles, terms and conditions common for companies with similar types of operations. Environmental We are subject to various U.S. federal, state and local laws and regulations, as well as Canadian federal and provincial laws, regarding air and water quality, climate change, hazardous and solid waste disposal and other environmental matters. These laws and regulations can change from time to time, imposing new obligations on us. Like others in the energy industry, we and our affiliates are responsible for environmental remediation at various contaminated sites. These include some properties that are part of our ongoing operations, sites formerly owned or used by us, and sites owned by third parties. Remediation typically involves management of contaminated soils and may involve groundwater remediation. Managed in conjunction with relevant federal, state/provincial and local agencies, activities vary with site conditions and locations, remedial requirements, complexity and sharing of responsibility. If remediation activities involve statutory joint and several liability provisions, strict liability, or cost recovery or contribution actions, we or our affiliates could potentially be held responsible for contamination caused by other parties. In some instances, we may share liability associated with contamination with other potentially responsible parties, and may also benefit from contractual indemnities that cover some or all cleanup costs. All of these sites generally are managed in the normal course of business or affiliated operations. Included in Deferred Credits and Other Liabilities—Regulatory and Other on the Consolidated Balance Sheets are undiscounted liabilities related to extended environmental-related activities totaling approximately $6 million as of December 31, 2016 and $8 million as of December 31, 2015 . These liabilities represent provisions for costs associated with remediation activities at some of our current and former sites, as well as other environmental contingent liabilities. Litigation Litigation and Legal Proceedings. We are involved in legal, tax and regulatory proceedings in various forums arising in the ordinary course of business, including matters regarding contract and payment claims, some of which involve substantial monetary amounts. We have insurance coverage for certain of these losses should they be incurred. We believe that the final disposition of these proceedings will not have a material effect on our consolidated results of operations, financial position or cash flows. Legal costs related to the defense of loss contingencies are expensed as incurred. We had no material reserves for legal matters related to litigation recorded as of December 31, 2016 or 2015 . Other Commitments and Contingencies See Note 22 for a discussion of guarantees and indemnifications. Operating Lease Commitments We lease assets in various areas of our operations. Consolidated rental expense for operating leases classified in Operating Income was $39 million in 2016 , $47 million for 2015 and $38 million for 2014 , which is included in Operating, Maintenance and Other on the Consolidated Statements of Operations. The following is a summary of future minimum lease payments under operating leases which at inception had noncancellable terms of more than one year. We had no material capital lease commitments as of December 31, 2016 or 2015 . Long-term Operating Leases (in millions) 2017 $ 39 2018 38 2019 38 2020 34 2021 31 Thereafter 151 Total future minimum lease payments $ 331

Guarantees and Indemnifications

Guarantees and Indemnifications	12 Months Ended
	Dec. 31, 2016
Guarantees [Abstract]
Guarantees and Indemnifications	Guarantees and Indemnifications We have various financial guarantees and indemnifications which are issued in the normal course of business. As discussed below, these contracts include financial guarantees, stand-by letters of credit, debt guarantees, surety bonds and indemnifications. We enter into these arrangements to facilitate a commercial transaction with a third party by enhancing the value of the transaction to the third party. To varying degrees, these guarantees involve elements of performance and credit risk, which are not included on our Consolidated Balance Sheets. The possibility of having to perform under these guarantees and indemnifications is largely dependent upon future operations of various subsidiaries, investees and other third parties, or the occurrence of certain future events. We have issued performance guarantees to customers and other third parties that guarantee the payment and performance of other parties, including certain non-100%-owned entities. In connection with our spin-off from Duke Energy in 2007, certain guarantees that were previously issued by us were assigned to, or replaced by, Duke Energy as guarantor in 2006. For any remaining guarantees of other Duke Energy obligations, Duke Energy has indemnified us against any losses incurred under these guarantee arrangements. The maximum potential amount of future payments we could have been required to make under these performance guarantees as of December 31, 2016 was approximately $406 million , which has been indemnified by Duke Energy as discussed above. One of these outstanding performance guarantees, which has a maximum potential amount of future payment of $201 million , expires in 2028 . The remaining guarantees have no contractual expirations. On December 29, 2016, SEP issued performance guarantees to a third party and an affiliate on behalf of an equity method investee. These guarantees were issued to enable the equity method investee to enter into long-term transportation contracts with the third party. While the likelihood is remote, the maximum potential amount of future payment SEP could have been required to make as of December 31, 2016 was $50 million . These performance guarantees expire in 2032 . We have also issued joint and several guarantees to some of the Duke/Fluor Daniel (D/FD) project owners, guaranteeing the performance of D/FD under its engineering, procurement and construction contracts and other contractual commitments in place at the time of our spin-off from Duke Energy. D/FD is one of the entities transferred to Duke Energy in connection with our spin-off. Substantially all of these guarantees have no contractual expiration and no stated maximum amount of future payments that we could be required to make. Fluor Enterprises Inc., as 50% owner in D/FD, issued similar joint and several guarantees to the same D/FD project owners. Westcoast, a 100% -owned subsidiary, has issued performance guarantees to third parties guaranteeing the performance of unconsolidated entities, such as equity method investees, and of entities previously sold by Westcoast to third parties. Those guarantees require Westcoast to make payment to the guaranteed third party upon the failure of such unconsolidated or sold entity to make payment under some of its contractual obligations, such as debt agreements, purchase contracts and leases. On December 30, 2016, in connection with our 50% ownership in DCP Midstream, we agreed to guarantee our portion of the obligations of the joint venture under a $424 million term loan agreement. If DCP Midstream fails to meet its obligations under the credit agreement, our maximum potential total future payments to lenders under the guarantee would be $225 million . The guarantee will terminate upon the payment of all obligations under the credit agreement, which expires in December 2019 . We have entered into various indemnification agreements related to purchase and sale agreements and other types of contractual agreements with vendors and other third parties. These agreements typically cover environmental, litigation and other matters, as well as breaches of representations, warranties and covenants. Typically, claims may be made by third parties for various periods of time, depending on the nature of the claim. Our potential exposure under these indemnification agreements can range from a specified amount, such as the purchase price, to an unlimited dollar amount, depending on the nature of the claim and the particular transaction. We are unable to estimate the total potential amount of future payments under these indemnification agreements due to several factors, such as the unlimited exposure under certain guarantees. As of December 31, 2016 , the amounts recorded for the guarantees and indemnifications described above are not material, both individually and in the aggregate.

Issuances of Common Stock

Issuances of Common Stock	12 Months Ended
	Dec. 31, 2016
Issuances of Common Stock [Abstract]
Issuances of Common Stock	Issuances of Common Stock On March 1, 2016, we entered into an equity distribution agreement under which we may sell and issue common stock up to an aggregate offering price of $500 million . The equity distribution agreement allows us to offer and sell common stock at prices deemed appropriate through sales agents. Sales of common stock under the equity distribution agreement will be made by means of ordinary brokers’ transactions through the facilities of the NYSE, in block transactions, or as otherwise agreed upon by one or more of the sales agents and us. We intend to use the net proceeds from sales under this at-the-market program for general corporate purposes, including investments in subsidiaries to fund capital expenditures. We issued approximately 12.9 million of common shares to the public under this program, for total net proceeds of $383 million through December 31, 2016 . In April 2016, we issued 16.1 million common shares to the public for net proceeds of approximately $479 million . Net proceeds from the offering were used to purchase approximately 10.4 million common units in SEP. SEP used the proceeds from our unit purchase for general corporate purposes, including the funding of its current expansion capital plan.

Effects of Changes in Noncontro

Effects of Changes in Noncontrolling Interests Ownership	12 Months Ended
	Dec. 31, 2016
Noncontrolling Interest [Abstract]
Effect of Changes In Noncontrolling Interests Ownership	Effects of Changes in Noncontrolling Interests Ownership The following table presents the effects of changes in our ownership interests in non-100%-owned consolidated subsidiaries: 2016 2015 2014 (in millions) Net income—controlling interests $ 693 $ 196 $ 1,082 Increase (decrease) in additional paid-in capital resulting from issuances/retirements of SEP units (a) 31 (105 ) 49 Total net income—controlling interests and changes in equity—controlling interests $ 724 $ 91 $ 1,131 ________________ (a) See Note 2 for further discussion.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Spectra Energy Corp 2007 Long-Term Incentive Plan (the 2007 LTIP), as amended and restated, provides for the granting of stock options, restricted and unrestricted stock awards and units, and other equity-based awards, to employees and other key individuals who perform services for us. A maximum of 53 million shares of common stock may be awarded under the 2007 LTIP. Restricted, performance and phantom awards granted under the 2007 LTIP typically become 100% vested on the three -year anniversary of the grant date. Equity-classified and liability-classified stock-based compensation cost is measured at the grant date based on the fair value of the award. Liability-classified stock-based compensation cost is re-measured at each reporting period until settlement. Related compensation expense is recognized over the requisite service period, which generally begins on the date the award is granted through the earlier of the date the award becomes vested, the date the employee becomes retirement-eligible, or the date the market or performance condition is met. Options granted under the 2007 LTIP are issued with exercise prices equal to the fair market value of our common stock on the grant date, have ten -year terms and vest ratably over a three -year term. Compensation expense related to stock options is recognized over the requisite service period. The requisite service period for stock options is the same as the vesting period, with the exception of retirement eligible employees, who have shorter requisite service periods ending when the employees become retirement eligible. We issue new shares upon exercising or vesting of share-based awards. The Black-Scholes option-pricing model is used to estimate the fair value of options at grant date. We recorded pre-tax stock-based compensation expense as follows, the components of which are described further below: 2016 2015 2014 (in millions) Phantom awards $ 25 $ 11 $ 14 Performance awards 27 18 13 Stock Options 1 — — Total $ 53 $ 29 $ 27 The tax benefit in Net Income associated with the recorded stock-based compensation expense was $10 million in 2016 and $7 million in both 2015 and 2014 . We recognized tax benefits from stock-based compensation cost of approximately $11 million in 2016 , $1 million in 2015 and $3 million in 2014 in Additional Paid-in Capital. Awards Activity Performance Awards Phantom Awards Units Weighted Average Grant Date Fair Value Units Weighted Average Grant Date Fair Value (thousands) (thousands) Outstanding at December 31, 2015 1,702 $ 39 1,212 $ 28 Granted 594 53 543 29 Vested (687 ) 38 (504 ) 32 Forfeited (259 ) 37 (51 ) 27 Outstanding at December 31, 2016 1,350 49 1,200 39 Awards expected to vest 1,302 49 1,168 39 Performance Awards Under the 2007 LTIP, we can also grant stock-based performance awards. The performance awards generally vest over three years at the earliest, if performance metrics are met. There were no liability-classified awards outstanding in 2016. The 2015 and 2014 liability-classified awards were settled in cash at vesting. We granted 593,600 equity-classified awards during 2016 , 564,300 during 2015 and 557,100 during 2014 , with fair values of $31 million , $27 million , and $26 million , respectively. We did not grant liability-classified awards during 2016 , 2015 or 2014 . Of the unvested and outstanding performance awards granted, 1,350,249 awards contain market conditions based on the total shareholder return of Spectra Energy common stock relative to a pre-defined peer group. The equity-classified and liability-classified awards with market conditions are valued using the Monte Carlo valuation method. The liability-classified awards are remeasured at each reporting period until settlement. Weighted-Average Assumptions for Stock-Based Performance Awards 2016 2015 2014 Risk-free rate of return 0.9% 1.1% 0.7% Expected life 3 years 3 years 3 years Expected volatility—Spectra Energy 24% 18% 20% Expected volatility—peer group 19%-69% 13%-27% 14%–32% The risk-free rate of return was determined based on a yield of three-year U.S. Treasury bonds on the grant date. The expected volatility was established based on historical volatility over three years using daily stock price observations. Because the award payout includes dividend equivalents, no dividend yield assumption is required. The total fair value of the shares vested was $26 million in 2016 , less than $1 million in 2015 and $20 million in 2014 . As of December 31, 2016 , we expect to recognize $27 million of future compensation cost related to outstanding performance awards over a weighted-average period of less than 2 years. Phantom Awards Under the 2007 LTIP, we can also grant stock-based phantom awards. The phantom awards generally vest over three years. The liability-classified awards will be settled in cash at vesting. We awarded 240,610 equity-classified awards to our employees in 2016 , 39,200 in 2015 and 101,500 in 2014 , with fair values of $7 million , $1 million and $4 million , respectively. We awarded 302,150 liability-classified awards to our employees in 2016 and 356,100 in 2015 and 353,000 in 2014, with fair values of $9 million in 2016 and $13 million in both 2015 and 2014. The liability-classified awards are remeasured at each reporting period until settlement. The total fair value of the shares vested was $16 million in 2016 , $13 million in 2015 and $11 million in 2014 . As of December 31, 2016 , we expect to recognize $17 million of future compensation cost related to phantom awards over a weighted-average period of less than two years. Stock Option Activity Options Weighted- Average Exercise Price Weighted- Average Remaining Life Aggregate Intrinsic Value (in thousands) (in years) (in millions) Outstanding at December 31, 2015 958 $ 26 1.2 $ — Granted 925 28 Exercised (875 ) 26 Forfeited or expired (33 ) 28 Outstanding at December 31, 2016 975 28 8.4 13 Exercisable at December 31, 2016 86 26 0.5 1 We awarded 925,300 non-qualified stock options to employees during 2016 , with a fair value of $2 million . We did not award any non-qualified stock options to employees during 2015 or 2014 . Weighted-Average Assumptions for Option Pricing 2016 Risk-free rate of return 1.4% Expected life 6 years Expected volatility 22.7% Expected dividend yield 5.7% The risk-free rate of return was determined based on a yield curve of U.S. Treasury rates ranging from six months to ten years and a period commensurate with the expected life of the options granted. The expected volatility was established based on historical volatility over six years using daily stock price observations. The expected dividend yield was determined based on the most recent annual dividend and the stock price at the time of grant. The total intrinsic value of options exercised was $11 million in 2016 , $1 million in 2015 and $6 million in 2014 . Cash received by us from options exercised was $22 million in 2016 , $3 million in 2015 and $11 million in 2014 . As of December 31, 2016, we expect to recognize $1 million of future compensation costs related to these stock options over a weighted average period of less than two years.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	Employee Benefit Plans Retirement Plans. We have a qualified non-contributory defined benefit (DB) retirement plan for U.S. employees (U.S. Qualified Pension Plan). This plan covers U.S. employees using a cash balance formula. Under a cash balance formula, a plan participant accumulates a retirement benefit consisting of pay credits that are based upon a percentage (which may vary with age and years of service) of current eligible earnings and current interest credits. We also maintain non-qualified, non-contributory, unfunded defined benefit plans (U.S. Non-Qualified Pension Plans) which cover certain current and former U.S. executives. The U.S. Non-Qualified Pension Plans have no plan assets. There are other non-qualified plans such as savings and deferred compensation plans which cover certain current and former U.S. executives. Pursuant to trust agreements, Spectra Energy has set aside funds for certain of the above non-qualified plans in several trusts. Although these funds are restrictive in nature, they remain a component of our general assets and are subject to the claims of creditors. These trust funds totaling $64 million as of December 31, 2016 and $18 million as of December 31, 2015 , invested in money market funds and valued using a Level 1 hierarchy level, are considered AFS securities and are classified as Investments and Other Assets—Other on the Consolidated Balance Sheets. In addition, our Westcoast subsidiary maintains qualified and non-qualified, contributory and non-contributory DB (Canadian Qualified Pension Plan and Canadian Non-Qualified Pension Plan, respectively) and defined contribution (Canadian DC) retirement plans covering substantially all employees of our Canadian operations. The DB plans provide retirement benefits based on each plan participant’s years of service and final average earnings. Under the Canadian DC plan, company contributions are determined according to the terms of the plan and based on each plan participant’s age, years of service and current eligible earnings. We also provide non-qualified DB supplemental pensions to all employees who retire under a DB qualified pension plan and whose pension is limited by the maximum pension limits under the Income Tax Act (Canada). We report our Canadian benefit plans separate from the U.S. plans due to differences in actuarial assumptions. Our policy is to fund our retirement plans, where applicable, on an actuarial basis to provide assets sufficient to meet benefits to be paid to plan participants or as required by legislation or plan terms. We made contributions to our U.S. Qualified and Non-Qualified Pension Plans of $22 million in both 2016 and 2015 and $21 million in 2014 . We made total contributions to our Canadian Qualified and Non-Qualified Pension Plans of $17 million in 2016 , $22 million in 2015 and $36 million in 2014 . Contributions of $8 million in both 2016 and 2015 and $9 million in 2014 were made to our Canadian DC plan. We anticipate that in 2017 we will make total contributions of approximately $2 million to the U.S. Qualified and Non-Qualified Pension Plans, approximately $24 million to the Canadian Qualified and Non-Qualified Pension Plans and approximately $8 million to the Canadian DC Plan. Actuarial gains and losses are amortized over the average remaining service period of active employees. The average remaining service period of active employees covered by the U.S. Qualified and Non-Qualified Pension Plans is 11 years. The average remaining service periods of active employees covered by the Canadian Qualified and Non-Qualified Pension Plans is 13 years. We determine the market-related value of plan assets using a calculated value that recognizes changes in fair value of the plan assets over five years for the U.S. plans and over three years for the Canadian plans. Qualified and Non-Qualified Pension Plans Change in Projected Benefit Obligation and Change in Fair Value of Plan Assets U.S. Canada 2016 2015 2016 2015 (in millions) Change in Projected Benefit Obligation Projected benefit obligation, beginning of period $ 571 $ 586 $ 1,034 $ 1,202 Service cost 19 19 28 28 Interest cost 25 24 43 43 Actuarial loss (gain) 21 (18 ) 30 (3 ) Participant contributions — — 5 5 Benefits paid (41 ) (40 ) (48 ) (47 ) Settlement effect — — (13 ) — Foreign currency translation effect — — 31 (194 ) Projected benefit obligation, end of period 595 571 1,110 1,034 Change in Fair Value of Plan Assets Plan assets, beginning of period 532 551 908 1,050 Actual return on plan assets 41 (1 ) 55 52 Benefits paid (41 ) (40 ) (48 ) (47 ) Employer contributions 22 22 17 22 Plan participants’ contributions — — 5 5 Expected non-investment expenses — — (3 ) (3 ) Settlement effect — — (11 ) — Foreign currency translation effect — — 26 (171 ) Plan assets, end of period 554 532 949 908 Net amount recognized $ (41 ) $ (39 ) $ (161 ) $ (126 ) Accumulated Benefit Obligation $ 569 $ 549 $ 1,041 $ 967 U.S. Canada 2016 2015 2016 2015 (in millions) Net amount recognized Current Liabilities—Other $ (2 ) $ (2 ) $ (6 ) $ (5 ) Deferred Credits and Other Liabilities—Regulatory and Other (39 ) (37 ) (175 ) (142 ) Investments and Other Assets—Other — — 20 21 Total net amount recognized $ (41 ) $ (39 ) $ (161 ) $ (126 ) The tables above include certain nonqualified pension plans that are unfunded. Those U.S. plans had projected benefit obligations of $24 million at December 31, 2016 and $23 million at December 31, 2015 . Those Canadian plans had projected benefit obligations of $112 million at December 31, 2016 and $103 million at December 31, 2015 . At December 31, 2016 , U.S. plans with accumulated benefit obligations in excess of plan assets had projected benefit obligations of $24 million , accumulated benefit obligations of $21 million and no plan assets. Canadian plans with accumulated benefit obligations in excess of plan assets had projected benefit obligations of $811 million , accumulated benefit obligations of $748 million and plan assets with a fair value of $631 million . Amounts Recognized in Accumulated Other Comprehensive Income U.S. Canada December 31, December 31, 2016 2015 2016 2015 (in millions) Net actuarial loss $ 167 $ 156 $ 348 $ 330 Prior service cost — — 3 5 Total amount recognized in AOCI $ 167 $ 156 $ 351 $ 335 Components of Net Periodic Pension Costs U.S. Canada 2016 2015 2014 2016 2015 2014 (in millions) Net Periodic Pension Cost Service cost benefit earned $ 19 $ 19 $ 19 $ 31 $ 31 $ 29 Interest cost on projected benefit obligation 25 24 24 43 43 52 Expected return on plan assets (39 ) (42 ) (39 ) (64 ) (65 ) (69 ) Amortization of prior service cost — — — 1 1 2 Amortization of loss 7 10 13 18 25 22 Curtailment effect — — — 1 — — Settlement effect — — — 1 — — Net periodic pension cost 12 11 17 31 35 36 Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Current year actuarial loss 18 25 8 39 10 93 Amortization of actuarial loss (7 ) (10 ) (13 ) (18 ) (25 ) (22 ) Amortization of prior service credit — — — (1 ) (1 ) (2 ) Curtailment effect — — — (1 ) — — Settlement effect — — — (3 ) — — Total recognized in other comprehensive income 11 15 (5 ) 16 (16 ) 69 Total Recognized in Net Periodic Pension Cost and Other Comprehensive Income $ 23 $ 26 $ 12 $ 47 $ 19 $ 105 In 2017, approximately $8 million of actuarial losses for the U.S. plans and $16 million for the Canadian plans will be amortized from AOCI on the Consolidated Balance Sheets into net periodic pension cost, and approximately $1 million of prior service credits will be amortized from AOCI into net periodic pension costs for the Canadian plans. Assumptions Used for Pension Benefits Accounting U.S. Canada 2016 2015 2014 2016 2015 2014 Benefit Obligations Discount rate 4.11 % 4.58 % 4.10 % 3.81 % 4.03 % 4.00 % Salary increase 4.00 4.00 4.00 3.00 3.00 3.25 Net Periodic Benefit Cost Discount rate 4.58 4.10 4.31 4.03 4.00 4.81 Salary increase 4.00 4.00 4.61 3.00 3.25 3.25 Expected long-term rate of return on plan assets 7.50 8.00 8.00 7.15 7.40 7.40 The discount rates used to determine the benefit obligations are the rates at which the benefit obligations could be effectively settled. The discount rates for our U.S. and Canadian plans are developed from yields on available high-quality bonds in each country and reflect each plan’s expected cash flows. The long-term rates of return for the U.S. and Canadian plan assets as of December 31, 2016 were developed using weighted-average calculations of expected returns based primarily on future expected returns across classes considering the use of active asset managers applied against the U.S. and Canadian plans’ respective targeted asset mix. Qualified Pension Plan Assets U.S. Canada Asset Category Target Allocation December 31, Target Allocation December 31, 2016 2015 2016 2015 U.S. equity securities 23 % 22 % 22 % 15 % 16 % 18 % Canadian equity securities — — — 23 28 24 Other equity securities 10 9 10 15 15 13 Fixed income securities 57 58 57 39 41 45 Other investments 10 11 11 8 — — Total 100 % 100 % 100 % 100 % 100 % 100 % Pension plan assets are maintained in master trusts in both the U.S. and Canada. The investment objective of the master trusts is to achieve reasonable returns on trust assets, subject to a prudent level of portfolio risk, for the purpose of enhancing the security of benefits for plan participants. The asset allocation targets were set after considering the investment objective and the risk profile with respect to the trusts. Equities are held for their high expected return. Other equity and fixed income securities are held for diversification. Investments within asset classes are diversified to achieve broad market participation and reduce the effects of individual managers or investments. We regularly review our actual asset allocation and periodically rebalance our investments to the targeted allocation when considered appropriate. The following table summarizes the fair values of pension plan assets recorded at each fair value hierarchy level, as determined in accordance with the valuation techniques described in Note 19: U.S. Canada Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 (in millions) December 31, 2016 Cash and cash equivalents $ 3 $ 3 $ — $ — $ 3 $ 3 $ — $ — Equity securities 171 171 — — 561 266 295 — Fixed income securities 317 317 — — 385 385 — — Other 63 — — 63 — — — — Total $ 554 $ 491 $ — $ 63 $ 949 $ 654 $ 295 $ — December 31, 2015 Cash and cash equivalents $ 2 $ 2 $ — $ — $ 3 $ 3 $ — $ — Equity securities 171 171 — — 501 221 280 — Fixed income securities 304 304 — — 404 404 — — Other 55 — — 55 — — — — Total $ 532 $ 477 $ — $ 55 $ 908 $ 628 $ 280 $ — The following presents changes in Level 3 assets that are measured at fair value on a recurring basis using significant unobservable inputs: U.S. 2016 2015 (in millions) Fair value, beginning of period $ 55 $ 53 Gain included in other comprehensive income 8 2 Fair value, end of period $ 63 $ 55 Expected Benefit Payments U.S. Canada (in millions) 2017 $ 104 $ 49 2018 46 51 2019 48 53 2020 47 55 2021 49 57 Thereafter 231 313 Other Post-Retirement Benefit Plans U.S. Other Post-Retirement Benefits. We provide certain health care and life insurance benefits for retired employees on a contributory and non-contributory basis. Employees are eligible for these benefits if they have met age and service requirements at retirement, as defined in the plans. These benefit costs are accrued over an employee’s active service period to the date of full benefits eligibility. Actuarial gains and losses are amortized over the average remaining service period of the active employees of 14 years. We determine the market-related value of the plan assets using a calculated value that recognizes changes in fair value of the plan assets over five years for the U.S. plans. Canadian Other Post-Retirement Benefits. We provide health care and life insurance benefits for retired employees on a non-contributory basis for our Canadian operations predominantly under defined contribution plans. Employees are eligible for these benefits if they have met age and service requirements at retirement, as defined in the plans. The Canadian plans are not funded. Other Post-Retirement Benefit Plans—Change in Projected Benefit Obligation and Fair Value of Plan Assets U.S. Canada 2016 2015 2016 2015 (in millions) Change in Benefit Obligation Accumulated post-retirement benefit obligation, beginning of period $ 166 $ 172 $ 107 $ 133 Service cost 1 1 3 4 Interest cost 8 7 4 5 Plan participants’ contributions 3 3 — — Actuarial loss (gain) 4 1 (5 ) (11 ) Medicare subsidy receivable 1 2 — — Benefits paid (18 ) (20 ) (4 ) (4 ) Plan change 10 — — — Curtailment effect — — (1 ) — Foreign currency translation effect — — 4 (20 ) Accumulated post-retirement benefit obligation, end of period 175 166 108 107 Change in Fair Value of Plan Assets Plan assets, beginning of period 88 92 — — Actual return on plan assets 5 1 — — Benefits paid (18 ) (20 ) (4 ) (4 ) Employer contributions 1 12 4 4 Plan participants’ contributions 3 3 — — Plan assets, end of period 79 88 — — Net amount recognized (a) $ (96 ) $ (78 ) $ (108 ) $ (107 ) _______ (a) Recognized primarily in Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets. Other Post-Retirement Benefit Plans—Amounts Recognized in Accumulated Other Comprehensive Income U.S. Canada December 31, December 31, 2016 2015 2016 2015 (in millions) Prior service cost (credit) $ 9 $ — $ (2 ) $ (3 ) Net actuarial loss (gain) 7 3 (4 ) 1 Total amount recognized in AOCI $ 16 $ 3 $ (6 ) $ (2 ) In 2017 , $1 million of prior service costs will be amortized from AOCI into net periodic pension costs for the U.S. plans and approximately $1 million for the Canadian plans. U.S. Canada 2016 2015 2014 2016 2015 2014 (in millions) Other Post-Retirement Benefit Plans—Components of Net Periodic Benefit Cost Service cost benefit earned $ 1 $ 1 $ 1 $ 3 $ 4 $ 4 Interest cost on accumulated post-retirement benefit obligation 8 7 8 4 5 6 Expected return on plan assets (5 ) (6 ) (5 ) — — — Amortization of prior service cost (credit) 1 — — (1 ) (1 ) (1 ) Amortization of loss — — 1 — — — Curtailment effect — — — (1 ) — — Net periodic other post-retirement benefit cost 5 2 5 5 8 9 Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net prior service cost 10 — — — — — Current year actuarial loss (gain) 4 7 (9 ) (5 ) (11 ) 6 Amortization of actuarial loss — — (1 ) — — — Amortization of prior service cost (credit) (1 ) — — 1 1 1 Total recognized in other comprehensive income 13 7 (10 ) (4 ) (10 ) 7 Total recognized in net periodic benefit cost and other comprehensive income $ 18 $ 9 $ (5 ) $ 1 $ (2 ) $ 16 Other Post-Retirement Benefits Plans—Assumptions Used for Benefits Accounting U.S. Canada 2016 2015 2014 2016 2015 2014 Benefit Obligations Discount rate 4.05 % 4.53 % 4.08 % 3.81 % 4.03 % 4.00 % Salary increase 4.00 4.00 4.00 3.00 3.00 3.25 Net Periodic Benefit Cost Discount rate 4.53 4.08 4.46 4.03 4.00 4.83 Salary increase 4.00 4.00 4.61 3.00 3.25 3.25 Expected return on plan assets 6.33 6.83 6.98 N/A N/A N/A The discount rates used to determine the post-retirement obligations are the rates at which the benefit obligations could be effectively settled. The discount rates for our U.S. and Canadian plans are developed from yields on available high-quality bonds in each country and reflect each plan’s expected cash flows. Assumed Health Care Cost Trend Rates U.S. Canada 2016 2015 2016 2015 Health care cost trend rate assumed for next year 7.00% 7.00% 5.00% 5.50% Rate to which the cost trend is assumed to decline 5.00% 5.00% 5.00% 5.00% Year that the rate reaches the ultimate trend rate 2021 2020 2017 2017 Sensitivity to Changes in Assumed Health Care Cost Trend Rates U.S. Canada 1% Point Increase 1% Point Decrease 1% Point Increase 1% Point Decrease (in millions) Effect on total service and interest costs $ — $ — $ 1 $ — Effect on post-retirement benefit obligations 8 (7 ) 5 (4 ) Other Post-Retirement Plan Assets U.S. Asset Category December 31, 2016 2015 Cash and cash equivalents 5 % 3 % Equity securities 39 45 Fixed income securities 48 46 Other assets 8 6 Total 100 % 100 % A portion of our other post-retirement plan assets is maintained within the U.S. master trust discussed under the pension plans above. We invest other post-retirement plan assets in the Spectra Energy Corp Employee Benefits Trust (VEBA I) and the Spectra Energy Corp Post-Retirement Medical Benefits Trust (VEBA II). The investment objective of the VEBAs is to achieve sufficient returns on trust assets, subject to a prudent level of portfolio risk, for the purpose of promoting the security of plan benefits for participants. The VEBA trusts are passively managed. The asset allocation table above includes the other post-retirement benefit assets held in the master trusts, VEBA I and VEBA II. The following table summarizes the fair values of the other post-retirement plan assets recorded at each fair value hierarchy level as determined in accordance with the valuation techniques described in Note 19: U.S. VEBA I and VEBA II Trusts Master Trust Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 (in millions) December 31, 2016 Cash and cash equivalents $ 4 $ 4 $ — $ — $ — $ — $ — $ — Equity securities 16 — 16 — 15 15 — — Fixed income securities 10 — 10 — 28 28 — — Other investments — — — — 6 — — 6 Total $ 30 $ 4 $ 26 $ — $ 49 $ 43 $ — $ 6 December 31, 2015 Cash and cash equivalents $ 3 $ 3 $ — $ — $ — $ — $ — $ — Equity securities 24 — 24 — 15 15 — — Fixed income securities 14 — 14 — 26 26 — — Other investments — — — — 5 — — 5 Total $ 41 $ 3 $ 38 $ — $ 46 $ 41 $ — $ 5 The following presents changes in Level 3 assets that are measured at fair value on a recurring basis using significant unobservable inputs: U.S. 2016 2015 (in millions) Fair value, beginning of period $ 5 $ 4 Unrealized gain included in other comprehensive income 1 1 Fair value, end of period $ 6 $ 5 Other Post-Retirement Benefit Plans—Payments and Receipts We expect to make future benefit payments, which reflect expected future service, as appropriate. As our plans provide benefits that are actuarially equivalent to the benefits received by Medicare recipients, we expect to receive future subsidies under Medicare Part D. The following benefit payments and subsidies are expected to be paid (or received) over each of the next five years and thereafter. Benefit Payments Medicare Part D Subsidy Receipts U.S. Canada U.S. (in millions) 2017 $ 16 $ 4 $ (2 ) 2018 16 4 (2 ) 2019 16 4 (2 ) 2020 15 4 (2 ) 2021 15 5 (2 ) Thereafter 63 26 (8 ) We anticipate making contributions of $3 million to the U.S. plans and $4 million to the Canadian plans in 2017 . Retirement/Savings Plan In addition to the retirement plans discussed above, we also have defined contribution employee savings plans available to both U.S. and Canadian employees. Employees may participate in a matching contribution where we match a certain percentage of before-tax employee contributions of up to 6% of eligible pay per pay period for U.S. employees and up to 5% of eligible pay per pay period for Canadian employees. We expensed pre-tax employer matching contributions of $15 million in 2016 , 2015 and 2014 for U.S employees. We expensed $12 million in 2016 and $13 million in 2015 and 2014 for Canadian employees.

Consolidating Financial Informa

Consolidating Financial Information	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Consolidating Financial Information	Condensed Consolidating Financial Information Spectra Energy Corp has agreed to fully and unconditionally guarantee the payment of principal and interest under all series of notes outstanding under the Senior Indenture of Spectra Capital, a 100%-owned, consolidated subsidiary. In accordance with the Securities and Exchange Commission (SEC) rules, the following condensed consolidating financial information is presented. The information shown for Spectra Energy Corp and Spectra Capital is presented utilizing the equity method of accounting for investments in subsidiaries, as required. The non-guarantor subsidiaries column represents all consolidated subsidiaries of Spectra Capital. This information should be read in conjunction with our accompanying Consolidated Financial Statements and notes thereto. Spectra Energy Corp Condensed Consolidating Statement of Operations Year Ended December 31, 2016 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Total operating revenues $ — $ — $ 4,919 $ (3 ) $ 4,916 Total operating expenses 7 4 3,323 (3 ) 3,331 Loss on sales of other assets and other, net — — (26 ) — (26 ) Operating income (loss) (7 ) (4 ) 1,570 — 1,559 Earnings from equity investments — — 97 — 97 Equity in earnings of consolidated subsidiaries 671 1,166 — (1,837 ) — Other income and expenses, net 1 — 173 — 174 Interest expense — 236 358 — 594 Earnings before income taxes 665 926 1,482 (1,837 ) 1,236 Income tax expense (benefit) (28 ) 255 (11 ) — 216 Net income 693 671 1,493 (1,837 ) 1,020 Net income—noncontrolling interests — — 327 — 327 Net income—controlling interests $ 693 $ 671 $ 1,166 $ (1,837 ) $ 693 Spectra Energy Corp Condensed Consolidating Statement of Operations Year Ended December 31, 2015 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Total operating revenues $ — $ — $ 5,237 $ (3 ) $ 5,234 Total operating expenses 6 (4 ) 3,806 (3 ) 3,805 Gain on sales of other assets and other, net — — 4 — 4 Operating income (loss) (6 ) 4 1,435 — 1,433 Loss from equity investments — — (290 ) — (290 ) Equity in earnings of consolidated subsidiaries 161 573 — (734 ) — Other income and expenses, net — 1 113 — 114 Interest expense — 244 392 — 636 Earnings before income taxes 155 334 866 (734 ) 621 Income tax expense (benefit) (41 ) 173 29 — 161 Net income 196 161 837 (734 ) 460 Net income—noncontrolling interests — — 264 — 264 Net income—controlling interests $ 196 $ 161 $ 573 $ (734 ) $ 196 Spectra Energy Corp Condensed Consolidating Statement of Operations Year Ended December 31, 2014 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Total operating revenues $ — $ — $ 5,906 $ (3 ) $ 5,903 Total operating expenses 6 1 3,974 (3 ) 3,978 Loss on sales of other assets and other, net — — (1 ) — (1 ) Operating income (loss) (6 ) (1 ) 1,931 — 1,924 Earnings from equity investments — — 361 — 361 Equity in earnings of consolidated subsidiaries 1,054 1,651 — (2,705 ) — Other income and expenses, net (2 ) 9 52 — 59 Interest expense — 253 426 — 679 Earnings before income taxes 1,046 1,406 1,918 (2,705 ) 1,665 Income tax expense (benefit) (36 ) 352 66 — 382 Net income 1,082 1,054 1,852 (2,705 ) 1,283 Net income—noncontrolling interests — — 201 — 201 Net income—controlling interests $ 1,082 $ 1,054 $ 1,651 $ (2,705 ) $ 1,082 Spectra Energy Corp Condensed Consolidating Statements of Comprehensive Income (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Year Ended December 31, 2016 Net income $ 693 $ 671 $ 1,493 $ (1,837 ) $ 1,020 Other comprehensive income (loss) (15 ) — 141 — 126 Total comprehensive income, net of tax 678 671 1,634 (1,837 ) 1,146 Less: comprehensive income—noncontrolling interests — — 330 — 330 Comprehensive income—controlling interests $ 678 $ 671 $ 1,304 $ (1,837 ) $ 816 Year Ended December 31, 2015 Net income $ 196 $ 161 $ 837 $ (734 ) $ 460 Other comprehensive income (loss) (14 ) 1 (931 ) — (944 ) Total comprehensive income (loss), net of tax 182 162 (94 ) (734 ) (484 ) Less: comprehensive income—noncontrolling interests — — 251 — 251 Comprehensive income (loss)—controlling interests $ 182 $ 162 $ (345 ) $ (734 ) $ (735 ) Year Ended December 31, 2014 Net income $ 1,082 $ 1,054 $ 1,852 $ (2,705 ) $ 1,283 Other comprehensive income (loss) 9 1 (596 ) — (586 ) Total comprehensive income, net of tax 1,091 1,055 1,256 (2,705 ) 697 Less: comprehensive income—noncontrolling interests — — 194 — 194 Comprehensive income—controlling interests $ 1,091 $ 1,055 $ 1,062 $ (2,705 ) $ 503 Spectra Energy Corp Condensed Consolidating Balance Sheet December 31, 2016 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Cash and cash equivalents $ — $ 10 $ 295 $ — $ 305 Receivables—consolidated subsidiaries 2 — 2 (4 ) — Notes receivable—current—consolidated subsidiaries — — 388 (388 ) — Receivables—other 1 1 1,001 — 1,003 Other current assets 16 2 446 — 464 Total current assets 19 13 2,132 (392 ) 1,772 Investments in and loans to unconsolidated affiliates — — 2,780 — 2,780 Investments in consolidated subsidiaries 8,403 18,579 — (26,982 ) — Advances receivable—consolidated subsidiaries — 720 — (720 ) — Notes receivable—consolidated subsidiaries — — 2,800 (2,800 ) — Goodwill — — 4,181 — 4,181 Other assets 86 18 289 — 393 Net property, plant and equipment — — 26,208 — 26,208 Regulatory assets and deferred debits 3 10 1,495 — 1,508 Total Assets $ 8,511 $ 19,340 $ 39,885 $ (30,894 ) $ 36,842 Accounts payable $ 3 $ 2 $ 823 $ — $ 828 Accounts payable—consolidated subsidiaries — 4 — (4 ) — Commercial paper — 631 822 — 1,453 Short-term borrowings—consolidated subsidiaries — 388 — (388 ) — Taxes accrued 2 — 84 — 86 Current maturities of long-term debt — — 551 — 551 Other current liabilities 92 51 844 — 987 Total current liabilities 97 1,076 3,124 (392 ) 3,905 Long-term debt — 2,886 10,738 — 13,624 Advances payable—consolidated subsidiaries 499 — 221 (720 ) — Notes payable—consolidated subsidiaries — 2,800 — (2,800 ) — Deferred credits and other liabilities 758 4,175 2,279 — 7,212 Preferred stock of subsidiaries — — 562 — 562 Equity Controlling interests 7,157 8,403 18,579 (26,982 ) 7,157 Noncontrolling interests — — 4,382 — 4,382 Total equity 7,157 8,403 22,961 (26,982 ) 11,539 Total Liabilities and Equity $ 8,511 $ 19,340 $ 39,885 $ (30,894 ) $ 36,842 Spectra Energy Corp Condensed Consolidating Balance Sheet December 31, 2015 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Cash and cash equivalents $ — $ 1 $ 212 $ — $ 213 Receivables—consolidated subsidiaries 15 6 13 (34 ) — Notes receivable—current—consolidated subsidiaries — — 387 (387 ) — Receivables—other 2 — 804 — 806 Other current assets 25 — 604 — 629 Total current assets 42 7 2,020 (421 ) 1,648 Investments in and loans to unconsolidated affiliates — — 2,592 — 2,592 Investments in consolidated subsidiaries 13,919 19,161 — (33,080 ) — Advances receivable—consolidated subsidiaries — 5,273 1,326 (6,599 ) — Notes receivable—consolidated subsidiaries — — 2,800 (2,800 ) — Goodwill — — 4,154 — 4,154 Other assets 41 27 242 — 310 Net property, plant and equipment — — 22,918 — 22,918 Regulatory assets and deferred debits 3 3 1,295 — 1,301 Total Assets $ 14,005 $ 24,471 $ 37,347 $ (42,900 ) $ 32,923 Accounts payable $ 2 $ 3 $ 506 $ — $ 511 Accounts payable—consolidated subsidiaries 4 28 2 (34 ) — Commercial paper — 481 631 — 1,112 Short-term borrowings—consolidated subsidiaries — 387 — (387 ) — Taxes accrued 5 — 73 — 78 Current maturities of long-term debt — — 652 — 652 Other current liabilities 102 48 889 — 1,039 Total current liabilities 113 947 2,753 (421 ) 3,392 Long-term debt — 2,891 10,001 — 12,892 Advances payable—consolidated subsidiaries 6,599 — — (6,599 ) — Notes payable—consolidated subsidiaries — 2,800 — (2,800 ) — Deferred credits and other liabilities 767 3,914 2,087 — 6,768 Preferred stock of subsidiaries — — 339 — 339 Equity Controlling interests 6,526 13,919 19,161 (33,080 ) 6,526 Noncontrolling interests — — 3,006 — 3,006 Total equity 6,526 13,919 22,167 (33,080 ) 9,532 Total Liabilities and Equity $ 14,005 $ 24,471 $ 37,347 $ (42,900 ) $ 32,923 Spectra Energy Corp Condensed Consolidating Statement of Cash Flows Year Ended December 31, 2016 (In millions) Spectra Energy Corp (a) Spectra Capital (a) Non-Guarantor Subsidiaries (a) Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 693 $ 671 $ 1,493 $ (1,837 ) $ 1,020 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Depreciation and amortization — — 799 — 799 Loss on sales of other assets and other, net — — 26 — 26 Earnings from equity investments — — (97 ) — (97 ) Equity in earnings of consolidated subsidiaries (671 ) (1,166 ) — 1,837 — Distributions from equity investments — — 111 — 111 Other (51 ) 268 (50 ) — 167 Net cash provided by (used in) operating activities (29 ) (227 ) 2,282 — 2,026 CASH FLOWS FROM INVESTING ACTIVITIES Capital expenditures — — (3,623 ) — (3,623 ) Investments in and loans to unconsolidated affiliates — — (251 ) — (251 ) Purchase of intangible, net — — (80 ) — (80 ) Dispositions — — 207 — 207 Purchases of held-to-maturity securities — — (633 ) — (633 ) Proceeds from sales and maturities of held-to-maturity securities — — 670 — 670 Purchases of available-for-sale securities — — (738 ) — (738 ) Proceeds from sales and maturities of available-for-sale securities — — 735 — 735 Distributions from equity investments — — 50 — 50 Advances from (to) affiliates (50 ) 118 — (68 ) — Distribution to equity investment — — (148 ) — (148 ) Other changes in restricted funds — — (20 ) — (20 ) Other — — 1 — 1 Net cash provided by (used in) investing activities (50 ) 118 (3,830 ) (68 ) (3,830 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from the issuance of long-term debt — — 1,183 — 1,183 Payments for the redemption of long-term debt — — (652 ) — (652 ) Net increase in commercial paper — 150 169 — 319 Distributions to noncontrolling interests — — (246 ) — (246 ) Contributions from noncontrolling interests — — 743 — 743 Proceeds from the issuances of Spectra Energy common stock 879 — — — 879 Proceeds from the issuance of SEP common units — — 579 — 579 Proceeds from the issuance of Westcoast preferred stock — — 229 — 229 Dividends paid on common stock (1,127 ) — — — (1,127 ) Distributions and advances from (to) affiliates 316 (23 ) (361 ) 68 — Other 11 (9 ) (19 ) — (17 ) Net cash provided by financing activities 79 118 1,625 68 1,890 Effect of exchange rate changes on cash — — 6 — 6 Net increase in cash and cash equivalents — 9 83 — 92 Cash and cash equivalents at beginning of period — 1 212 — 213 Cash and cash equivalents at end of period $ — $ 10 $ 295 $ — $ 305 ________ (a) Excludes the effects of $6,416 million of non-cash equitizations of advances receivable owed to Spectra Capital and Spectra Energy Corp. Spectra Energy Corp Condensed Consolidating Statement of Cash Flows Year Ended December 31, 2015 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 196 $ 161 $ 837 $ (734 ) $ 460 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Depreciation and amortization — — 778 — 778 Impairment charges — — 349 — 349 Gain on sales of other assets and other, net — — (4 ) — (4 ) Earnings from equity investments — — 290 — 290 Equity in earnings of consolidated subsidiaries (161 ) (573 ) — 734 — Distributions from equity investments — — 161 — 161 Other 187 33 (7 ) — 213 Net cash provided by (used in) operating activities 222 (379 ) 2,404 — 2,247 CASH FLOWS FROM INVESTING ACTIVITIES Capital expenditures — — (2,848 ) — (2,848 ) Investments in and loans to unconsolidated affiliates — — (124 ) — (124 ) Purchases of held-to-maturity securities — — (668 ) — (668 ) Proceeds from sales and maturities of held-to-maturity securities — — 695 — 695 Purchases of available-for-sale securities — — (95 ) — (95 ) Proceeds from sales and maturities of available-for-sale securities — — 87 — 87 Distributions from equity investments — — 451 — 451 Distribution to equity investment — — (248 ) — (248 ) Advances from (to) affiliates (240 ) 296 — (56 ) — Other changes in restricted funds — — (33 ) — (33 ) Other — — 1 — 1 Net cash provided by (used in) investing activities (240 ) 296 (2,782 ) (56 ) (2,782 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from the issuance of long-term debt — — 1,585 — 1,585 Payments for the redemption of long-term debt — — (285 ) — (285 ) Net increase (decrease) in commercial paper — 83 (522 ) — (439 ) Distributions to noncontrolling interests — — (198 ) — (198 ) Contributions from noncontrolling interests — — 248 — 248 Proceeds from the issuance of SEP common units — — 546 — 546 Proceeds from the issuance of Westcoast preferred stock — — 84 — 84 Dividends paid on common stock (996 ) — — — (996 ) Distributions and advances from (to) affiliates 1,018 — (1,074 ) 56 — Other (4 ) — (1 ) — (5 ) Net cash provided by financing activities 18 83 383 56 540 Effect of exchange rate changes on cash — — (7 ) — (7 ) Net decrease in cash and cash equivalents — — (2 ) — (2 ) Cash and cash equivalents at beginning of period — 1 214 — 215 Cash and cash equivalents at end of period $ — $ 1 $ 212 $ — $ 213 Spectra Energy Corp Condensed Consolidating Statement of Cash Flows Year Ended December 31, 2014 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 1,082 $ 1,054 $ 1,852 $ (2,705 ) $ 1,283 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Depreciation and amortization — — 809 — 809 Loss on sales of other assets and other, net — — 1 — 1 Earnings from equity investments — — (361 ) — (361 ) Equity in earnings of consolidated subsidiaries (1,054 ) (1,651 ) — 2,705 — Distributions from equity investments — — 380 — 380 Other 14 304 (209 ) — 109 Net cash provided by (used in) operating activities 42 (293 ) 2,472 — 2,221 CASH FLOWS FROM INVESTING ACTIVITIES Capital expenditures — — (2,028 ) — (2,028 ) Investments in and loans to unconsolidated affiliates — — (259 ) — (259 ) Purchases of held-to-maturity securities — — (790 ) — (790 ) Proceeds from sales and maturities of held-to-maturity securities — — 815 — 815 Purchases of available-for-sale securities — — (13 ) — (13 ) Proceeds from sales and maturities of available-for-sale securities — — 7 — 7 Distributions from equity investments — — 266 — 266 Advances from affiliates 92 495 — (587 ) — Other changes in restricted funds — — (1 ) — (1 ) Net cash provided by (used in) investing activities 92 495 (2,003 ) (587 ) (2,003 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from the issuance of long-term debt — 300 728 — 1,028 Payments for the redemption of long-term debt — (557 ) (627 ) — (1,184 ) Net increase in commercial paper — 54 520 — 574 Distributions to noncontrolling interests — — (175 ) — (175 ) Contributions from noncontrolling interests — — 145 — 145 Proceeds from the issuance of SEP common units — — 327 — 327 Dividends paid on common stock (925 ) — — — (925 ) Distributions and advances from (to) affiliates 777 (10 ) (1,354 ) 587 — Other 14 — (3 ) — 11 Net cash used in financing activities (134 ) (213 ) (439 ) 587 (199 ) Effect of exchange rate changes on cash — — (5 ) — (5 ) Net increase (decrease) in cash and cash equivalents — (11 ) 25 — 14 Cash and cash equivalents at beginning of period — 12 189 — 201 Cash and cash equivalents at end of period $ — $ 1 $ 214 $ — $ 215

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) First Quarter Second Quarter Third Quarter Fourth Quarter Total (in millions, except per share amounts) 2016 Operating revenues $ 1,384 $ 1,159 $ 1,075 $ 1,298 $ 4,916 Operating income 494 371 321 373 1,559 Net income 310 221 281 208 1,020 Net income—controlling interests 234 149 195 115 693 Earnings per share (a) Basic and diluted 0.35 0.21 0.28 0.16 1.00 2015 Operating revenues $ 1,623 $ 1,192 $ 1,103 $ 1,316 $ 5,234 Operating income 541 406 389 97 1,433 Net income (loss) 325 80 243 (188 ) 460 Net income (loss)—controlling interests 267 18 174 (263 ) 196 Earnings (loss) per share (a) Basic and diluted 0.40 0.03 0.26 (0.39 ) 0.29 ___________ (a) Quarterly earnings-per-share amounts are stand-alone calculations and may not be additive to full-year amounts due to rounding. Unusual or Infrequent Items Due to the significant downturn in commodity prices, DCP Midstream performed a goodwill impairment test and other asset impairment tests in 2015. The impairment tests resulted in DCP Midstream’s recognition of a $460 million goodwill impairment and $342 million in other asset impairments, net of tax, which reduced our equity earnings from DCP Midstream by $231 million after-tax for 2015. During the fourth quarter of 2015, we recorded goodwill impairments associated with the acquisition of Westcoast in 2002 for BC Field Services and Empress, which impacted net income by $270 million and $63 million , respectively. The impairments are included in Impairment of Goodwill and Other on the Consolidated Statement of Operations. See Note 13 for further discussion.

SCHEDULE II-VALUATION AND QUALI

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	12 Months Ended
	Dec. 31, 2016
Valuation and Qualifying Accounts [Abstract]
SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	SPECTRA ENERGY CORP SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS AND RESERVES Balance at Beginning of Period Additions: Deductions (a) Balance at End of Period Charged to Expense Charged to Other Accounts (in millions) December 31, 2016 Allowance for doubtful accounts $ 11 $ 9 $ — $ 10 $ 10 Other (b) 134 42 8 71 113 $ 145 $ 51 $ 8 $ 81 $ 123 December 31, 2015 Allowance for doubtful accounts $ 11 $ 7 $ — $ 7 $ 11 Other (b) 113 36 24 39 134 $ 124 $ 43 $ 24 $ 46 $ 145 December 31, 2014 Allowance for doubtful accounts $ 10 $ 6 $ — $ 5 $ 11 Other (b) 164 29 — 80 113 $ 174 $ 35 $ — $ 85 $ 124 _________ (a) Principally cash payments and reserve reversals. (b) Principally income tax, insurance-related, litigation and other reserves, included primarily in Deferred Credits and Other Liabilities—Regulatory and Other on the Consolidated Balance Sheets.

Summary of Operations and Sig38

Summary of Operations and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Variable Interest Entity [Line Items]
Use of Estimates	Use of Estimates. To conform with generally accepted accounting principles (GAAP) in the U.S., we make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and Notes to Consolidated Financial Statements. Although these estimates are based on our best available knowledge at the time, actual results could differ.
Fair Value Measurements	Fair Value Measurements. We measure the fair value of financial assets and liabilities by maximizing the use of observable inputs and minimizing the use of unobservable inputs. Fair value is the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.
Cost-Based Regulation	Cost-Based Regulation. The economic effects of regulation can result in a regulated company recording assets for costs that have been or are expected to be approved for recovery from customers or recording liabilities for amounts that are expected to be returned to customers or for instances where the regulator provides current rates that are intended to recover costs that are expected to be incurred in the future. Accordingly, we record assets and liabilities that result from the regulated ratemaking process that may not be recorded under GAAP for non-regulated entities. We continually assess whether regulatory assets are probable of future recovery by considering factors such as applicable regulatory changes and recent rate orders to other regulated entities. Based on this assessment, we believe our existing regulatory assets are probable of recovery. These regulatory assets and liabilities are mostly classified in the Consolidated Balance Sheets as Regulatory Assets and Deferred Debits, and Deferred Credits and Other Liabilities—Regulatory and Other. We evaluate our regulated assets, and consider factors such as regulatory changes and the effect of competition. If cost-based regulation ends or competition increases, we may have to reduce our asset balances to reflect a market basis less than cost and write-off the associated regulatory assets and liabilities. See Note 5 for further discussion.
Foreign Currency Translation	Foreign Currency Translation. The Canadian dollar has been determined to be the functional currency of our Canadian operations based on an assessment of the economic circumstances of those operations. Assets and liabilities of our Canadian operations are translated into U.S. dollars at current exchange rates. Translation adjustments resulting from fluctuations in exchange rates are included as a separate component of Other Comprehensive Income on the Consolidated Statements of Comprehensive Income. Revenue and expense accounts of these operations are translated at average monthly exchange rates prevailing during the periods. Gains and losses arising from transactions denominated in currencies other than the functional currency are included in the results of operations of the period in which they occur. Foreign currency transaction losses totaled $1 million in 2016 and $6 million in 2015 and gains totaled $3 million in 2014 , and are included in Other Income and Expenses, Net on the Consolidated Statements of Operations. Deferred U.S. taxes related to translation gains and losses have not been provided on those Canadian operations where we expect the earnings to be indefinitely reinvested.
Revenue Recognition	Revenue Recognition. Revenues from the transmission, storage, processing, distribution and sales of natural gas, from the sales of NGLs and from the transportation and storage of crude oil are generally recognized when either the service is provided or the product is delivered. Revenues related to these services provided or products delivered but not yet billed are estimated each month. These estimates are generally based on contract data, regulatory information, estimated distribution usage based on historical data adjusted for heating degree days, commodity prices and preliminary throughput and allocation measurements. Final bills for the current month are billed and collected in the following month. Differences between actual and estimated revenues are immaterial. There were no customers accounting for 10% or more of consolidated revenues during 2016 , 2015 or 2014 . We also have certain customer contracts with billed amounts that decline annually over the terms of the contracts. Differences between the amounts billed and recognized are deferred on the Consolidated Balance Sheets.
Stock-Based Compensation	Stock-Based Compensation. For employee awards, equity-classified and liability-classified stock-based compensation cost is measured at the grant date based on the fair value of the award. Liability-classified stock-based compensation cost is remeasured at each reporting period until settlement. Related compensation expense is recognized over the requisite service period, which generally begins on the date the award is granted through the earlier of the date the award vests, the date the employee becomes retirement-eligible or the date the market or performance condition of the award is met. Awards, including stock options, granted to employees that are retirement-eligible are deemed to have vested immediately upon issuance, and therefore, compensation cost for those awards is recognized on the date such awards are granted. See Note 25 for further discussion.
Pension and Other Post-Retirement Benefits	Pension and Other Post-Retirement Benefits. We fully recognize the overfunded or underfunded status of our consolidating subsidiaries’ pension and other post-retirement benefit plans as Investments and Other Assets—Other, Current Liabilities—Other or Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets, as appropriate. A plan’s funded status is the difference between the fair value of plan assets and the plan’s projected benefit obligation. We record deferred plan costs and income (unrecognized losses and gains, and unrecognized prior service costs and credits) in Accumulated Other Comprehensive Income (AOCI) on the Consolidated Statements of Equity, until they are amortized and recognized as a component of benefit expense within Operating, Maintenance and Other in the Consolidated Statements of Operations. See Note 26 for further discussion.
Allowance for Funds Used During Construction (AFUDC)	Allowance for Funds Used During Construction (AFUDC). AFUDC, which represents the estimated debt and equity costs of capital funds necessary to finance the construction of certain new regulated facilities, consists of two components, an equity component and an interest expense component. After construction is completed, we are permitted to recover these costs through inclusion in the rate base and in the depreciation provision. AFUDC is capitalized as a component of Property, Plant and Equipment—Cost in the Consolidated Balance Sheets, with offsetting credits to the Consolidated Statements of Operations through Other Income and Expenses, Net for the equity component and Interest Expense for the interest expense component. The total amount of AFUDC included in the Consolidated Statements of Operations was $232 million in 2016 (an equity component of $164 million and an interest expense component of $68 million ), $143 million in 2015 (an equity component of $111 million and an interest expense component of $32 million ) and $72 million in 2014 (an equity component of $53 million and an interest expense component of $19 million ).
Income Taxes	Income Taxes. Deferred income taxes are recognized for differences between the financial reporting and tax bases of assets and liabilities at enacted statutory tax rates in effect for the years in which the differences are expected to reverse. The effect on deferred taxes of a change in tax rates is recognized in income in the period that includes the enactment date. Actual income taxes could vary from these estimates due to future changes in income tax law or results from the final review of tax returns by federal, state or foreign tax authorities. Financial statement effects on tax positions are recognized in the period in which it is more likely than not that the position will be sustained upon examination, the position is effectively settled or when the statute of limitations to challenge the position has expired. Interest and penalties related to unrecognized tax benefits are recorded as interest expense and other expense, respectively.
Cash and Cash Equivalents	Cash and Cash Equivalents. Highly liquid investments with original maturities of three months or less at the date of acquisition are considered cash equivalents, except for the investments that were pledged as collateral against long-term debt as discussed in Note 17 and any investments that are considered restricted funds
Inventory	Inventory. Inventory consists of natural gas held in storage for transmission and processing, and also includes materials and supplies. The NGLs previously included in inventory were disposed of as part of the sale of the Empress NGL operations (Empress) on August 4, 2016. See Note 3 for further discussion related to the sale of Empress. Natural gas inventories primarily relate to the Distribution segment in Canada and are valued at costs approved by the regulator, the Ontario Energy Board (OEB). The difference between the approved price and the actual cost of gas purchased is recorded in either Fuel Tracker or Other Current Liabilities on the Consolidated Balance Sheets, as appropriate, for future disposition with customers, subject to approval by the OEB. The remaining inventory is recorded at the lower of cost or market, primarily using average cost.
Natural Gas Imbalances	Natural Gas Imbalances. The Consolidated Balance Sheets include balances as a result of differences in gas volumes received and delivered for customers. Since settlement of certain imbalances is in-kind, changes in their balances do not have an effect on our Consolidated Statements of Cash Flows. Receivables include $407 million and $291 million as of December 31, 2016 and December 31, 2015, respectively, and Other Current Liabilities include $382 million and $287 million as of December 31, 2016 and December 31, 2015, respectively, related to gas imbalances. Most natural gas volumes owed to or by us are valued at natural gas market index prices as of the balance sheet dates.
Fair Value Measurement, Policy	Level 1 Level 1 valuations represent quoted unadjusted prices for identical instruments in active markets. Level 2 Valuation Techniques Fair values of our financial instruments that are actively traded in the secondary market, including our long-term debt, are determined based on market-based prices. These valuations may include inputs such as quoted market prices of the exact or similar instruments, broker or dealer quotations, or alternative pricing sources that may include models or matrix pricing tools, with reasonable levels of price transparency. For interest rate swaps, we utilize data obtained from a third-party source for the determination of fair value. Both the future cash flows for the fixed-leg and floating-leg of our swaps are discounted to present value. In addition, credit default swap rates are used to develop the adjustment for credit risk embedded in our positions. We believe that since some of the inputs and assumptions for the calculations of fair value are derived from observable market data, a Level 2 classification is appropriate. Level 3 Valuation Techniques Level 3 valuation techniques include the use of pricing models, discounted cash flow methodologies or similar techniques where at least one significant model assumption or input is unobservable. Level 3 financial instruments also include those for which the determination of fair value required significant management judgment or estimation. As of December 31, 2016 , there are no derivative financial instruments classified as Level 3. Those reported in Level 3 at December 31, 2015 consisted of NGL revenue swap contracts related to the Empress assets in Western Canada Transmission & Processing, which were disposed of on August 4, 2016. See Note 3 for further discussion related to the sale of Empress. As of December 31, 2015 , we reported certain of our NGL basis swaps at fair value using Level 3 inputs due to such derivatives not having observable market prices for substantially the full term of the derivative asset or liability. For valuations that included both observable and unobservable inputs, if the unobservable input was determined to be significant to the overall inputs, the entire valuation was categorized in Level 3. This included derivatives valued using indicative price quotations whose contract length extended into unobservable periods. The fair value of these NGL basis swaps was determined using a discounted cash flow valuation technique based on a forward commodity basis curve. For those derivatives, the primary input to the valuation model was the forward commodity basis curve, which was based on observable or public data sources and extrapolated when observable prices were not available.
Risk Management and Hedging Activities and Financial Instruments	Risk Management and Hedging Activities and Financial Instruments. Currently, our use of derivative instruments is primarily limited to interest rate positions. Prior to the sale of Empress on August 4, 2016, we maintained a commodity hedging program at the Western Canada Transmission & Processing segment. All derivative instruments that do not qualify for the normal purchases and normal sales exception are recorded on the Consolidated Balance Sheets at fair value. Cash inflows and outflows related to derivative instruments are a component of Cash Flows From Operating Activities in the accompanying Consolidated Statements of Cash Flows. Fair Value Hedges. Derivatives may be designated as a hedge of a recognized asset, liability or firm commitment (fair value hedge). For all hedge contracts, we prepare documentation of the hedge in accordance with accounting standards and assess whether the hedge contract is highly effective using regression analysis, both at inception and on a quarterly basis, in offsetting changes in fair values of hedged items. We document hedging activity by instrument type and risk management strategy. For derivatives designated as fair value hedges, we recognize the gain or loss on the derivative instrument, as well as the offsetting gain or loss on the hedged item in earnings, to the extent effective, in the current period. In the event the hedge is not effective, there is no offsetting gain or loss recognized in earnings for the hedged item. All derivatives designated and accounted for as hedges are classified in the same category as the item being hedged in the Consolidated Statements of Cash Flows. All components of each derivative gain or loss are included in the assessment of hedge effectiveness.
Investments	Investments. We may actively invest a portion of our available cash and restricted funds balances in various financial instruments, including taxable or tax-exempt debt securities. In addition, we invest in short-term money market securities, some of which are restricted due to debt collateral or insurance requirements. Investments in available-for-sale (AFS) securities are carried at fair value and investments in held-to-maturity (HTM) securities are carried at cost. Investments in money market securities are also accounted for at fair value. Realized gains and losses, and dividend and interest income related to these securities, including any amortization of discounts or premiums arising at acquisition, are included in earnings. The costs of securities sold are determined using the specific identification method. Purchases and sales of AFS and HTM securities are presented on a gross basis within Cash Flows From Investing Activities in the accompanying Consolidated Statements of Cash Flows.
Goodwill	Goodwill. We perform our goodwill impairment test annually and evaluate goodwill when events or changes in circumstances indicate that its carrying value may not be recoverable. In 2015, we recorded goodwill impairment charges of $270 million for BC Field Services and $63 million for Empress associated with the Westcoast Energy Inc. (Westcoast) acquisition in 2002. No impairments of goodwill were recorded in 2016 or 2014. See Note 13 for further discussion. We perform our annual review for goodwill impairment at the reporting unit level, which is identified by assessing whether the components of our operating segments constitute businesses for which discrete financial information is available, whether segment management regularly reviews the operating results of those components and whether the economic and regulatory characteristics are similar. We determined that our reporting units are equivalent to our reportable segments, except for the reporting units of our Western Canada Transmission & Processing and Spectra Energy Partners reportable segments, which are one level below. As permitted under accounting guidance on testing goodwill for impairment, we perform either a qualitative assessment or a quantitative assessment of each of our reporting units based on management’s judgment. With respect to our qualitative assessments, we consider events and circumstances specific to us, such as macroeconomic conditions, industry and market considerations, cost factors and overall financial performance, when evaluating whether it is more likely than not that the fair values of our reporting units are less than their respective carrying amounts. In connection with our quantitative assessments, we primarily use a discounted cash flow analysis to determine the fair values of those reporting units. Key assumptions in the determination of fair value included the use of an appropriate discount rate and estimated future cash flows. In estimating cash flows, we incorporate expected long-term growth rates in key markets served by our operations, regulatory stability, the ability to renew contracts, commodity prices (where appropriate) and foreign currency exchange rates, as well as other factors that affect our reporting units’ revenue, expense and capital expenditure projections. If the carrying amount of the reporting unit exceeds its fair value, a comparison of the fair value and carrying value of the goodwill of that reporting unit needs to be performed. If the carrying value of the goodwill of a reporting unit exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to the excess. Additional impairment tests are performed between the annual reviews if events or changes in circumstances make it more likely than not that the fair value of a reporting unit is below its carrying amount.
Property, Plant and Equipment	Property, Plant and Equipment. Property, plant and equipment is stated at historical cost less accumulated depreciation. We capitalize all construction-related direct labor and material costs, as well as indirect construction costs. Indirect costs include general engineering, taxes and the cost of funds used during construction. The costs of renewals and betterments that extend the useful life or increase the expected output of property, plant and equipment are also capitalized. The costs of repairs, replacements and major maintenance projects that do not extend the useful life or increase the expected output of property, plant and equipment are expensed as incurred. Depreciation is generally computed over the asset’s estimated useful life using the straight-line method. When we retire regulated property, plant and equipment, we charge the original cost plus the cost of retirement, less salvage value, to accumulated depreciation and amortization. When we sell entire regulated operating units or retire non-regulated properties, the cost is removed from the property account and the related accumulated depreciation and amortization accounts are reduced. Any gain or loss is recorded in earnings, unless otherwise required by the applicable regulatory body.
Preliminary Project Costs	Preliminary Project Costs. Project development costs, including expenditures for preliminary surveys, plans, investigations, environmental studies, regulatory applications and other costs incurred for the purpose of determining the feasibility of capital expansion projects, are capitalized for rate-regulated enterprises when it is determined that recovery of such costs through regulated revenues of the completed project is probable. Any inception-to-date costs of the project that were initially expensed are reversed and capitalized as Property, Plant and Equipment.
Long-Lived Asset Impairments	Long-Lived Asset Impairments. We evaluate whether long-lived assets, excluding goodwill, have been impaired when circumstances indicate the carrying value of those assets may not be recoverable. For such long-lived assets, an impairment exists when its carrying value exceeds the sum of estimates of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. When alternative courses of action to recover the carrying amount of a long-lived asset are under consideration, a probability-weighted approach is used in developing estimates of future undiscounted cash flows. If the carrying value of the long-lived asset is not recoverable based on these estimated future undiscounted cash flows, an impairment loss is measured as the excess of the asset’s carrying value over its fair value, such that the asset’s carrying value is adjusted to its estimated fair value. We assess the fair value of long-lived assets using commonly accepted techniques and may use more than one source. Sources to determine fair value include, but are not limited to, recent third-party comparable sales, internally developed discounted cash flow analyses and analyses from outside advisors. Significant changes in market conditions resulting from events such as changes in natural gas available to our systems, the condition of an asset, a change in our intent to utilize the asset or a significant change in contracted revenues or regulatory recoveries would generally require us to reassess the cash flows related to the long-lived assets.
Asset Retirement Obligations	Asset Retirement Obligations. We recognize asset retirement obligations (AROs) for legal commitments associated with the retirement of long-lived assets that result from the acquisition, construction, development and/or normal use of the asset and conditional AROs in which the timing or method of settlement are conditional on a future event that may or may not be within our control. The fair value of a liability for an ARO is recognized in the period in which it is incurred if a reasonable estimate of fair value can be made and is added to the carrying amount of the associated asset. This additional carrying amount is depreciated over the estimated useful life of the asset.
Unamortized Debt Premium, Discount and Expense	Unamortized Debt Premium, Discount and Expense. Premiums, discounts and expenses incurred with the issuance of outstanding long-term debt are amortized over the terms of the debt issues. Any call premiums or unamortized expenses associated with refinancing higher-cost debt obligations to finance regulated assets and operations are amortized consistent with regulatory treatment of those items, where appropriate.
Environmental Expenditures	Environmental Expenditures. We expense environmental expenditures related to conditions caused by past operations that do not generate current or future revenues. Environmental expenditures related to operations that generate current or future revenues are expensed or capitalized, as appropriate. Undiscounted liabilities are recorded when the necessity for environmental remediation becomes probable and the costs can be reasonably estimated, or when other potential environmental liabilities are reasonably estimable and probable.
Captive Insurance Reserves	Captive Insurance Reserves. We have captive insurance subsidiaries which provide insurance coverage to our consolidated subsidiaries as well as certain equity affiliates, on a limited basis, for various business risks and losses, such as workers compensation, property, business interruption and general liability. Liabilities include provisions for estimated losses incurred but not yet reported, as well as provisions for known claims which have been estimated on a claims-incurred basis. Incurred but not yet reported reserve estimates involve the use of assumptions and are based upon historical loss experience, industry data and other actuarial assumptions. Reserve estimates are adjusted in future periods as actual losses differ from historical experience.
Guarantees	Guarantees. Upon issuance or material modification of a guarantee made by us, we recognize a liability for the estimated fair value of the obligation we assume under that guarantee, if any. Fair value is estimated using a probability-weighted approach. We reduce the obligation over the term of the guarantee or related contract in a systematic and rational method as risk is reduced under the obligation.
Accounting For Sales of Stock by a Subsidiary	Accounting For Sales of Stock by a Subsidiary. Sales of stock by a consolidated subsidiary are accounted for as equity transactions in those instances where a change in control does not take place.
Segment Reporting	Segment Reporting. Operating segments are components of an enterprise for which separate financial information is available and evaluated regularly by the chief operating decision maker (CODM) in deciding how to allocate resources and evaluate performance. Two or more operating segments may be aggregated into a single reportable segment provided certain criteria are met. There is no such aggregation within our defined business segments. A description of our reportable segments, consistent with how business results are reported internally to management, and the disclosure of segment information is presented in Note 4.
Consolidated Statements of Cash Flows	Consolidated Statements of Cash Flows. Cash flows from discontinued operations are combined with cash flows from continuing operations within operating, investing and financing cash flows. Cash received from insurance proceeds are classified depending on the activity that resulted in the insurance proceeds. For example, business interruption insurance proceeds are included as a component of operating activities while insurance proceeds from damaged property are included as a component of investing activities. With respect to cash overdrafts, book overdrafts are included within operating cash flows while bank overdrafts, if any, are included within financing cash flows.
Distributions from Unconsolidated Affiliates	Distributions from Equity Investments. We consider distributions received from equity investments which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and classify these amounts as Cash Flows From Operating Activities within the accompanying Consolidated Statements of Cash Flows. Cumulative distributions received in excess of cumulative equity in earnings subsequent to the date of investment are considered to be a return of investment and are classified as Cash Flows From Investing Activities.
New Accounting Pronouncements	New Accounting Pronouncements. The following Accounting Standards Updates (ASUs) were adopted during 2016 and the effect of such adoption has been presented in the accompanying Consolidated Financial Statements: In June 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-10, “Development Stage Entities (Topic 915): Elimination of Certain Financial Reporting Requirements, Including an Amendment to Variable Interest Entities Guidance in Topic 810, Consolidation , ” which amends the consolidation guidance around reporting entities that invest in development stage entities. We adopted the consolidation guidance of this amendment on January 1, 2016 and applied it retrospectively with no material effect on our consolidated results of operations, financial position or cash flows. This ASU resulted in certain of our entities being classified as Variable Interest Entities (VIEs). See Note 11 for discussion of our VIEs. In February 2015, the FASB issued ASU No. 2015-02, “Consolidation (Topic 810): Amendments to the Consolidation Analysis,” which makes changes to both the variable interest model and the voting model. These changes required reevaluation of certain entities for consolidation and required us to revise our documentation regarding the consolidation or deconsolidation of such entities. We adopted this standard on January 1, 2016 with no material effect on our consolidated results of operations, financial position or cash flows. In September 2015, the FASB issued ASU No. 2015-16, “Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments , ” to simplify accounting for adjustments made to provisional amounts recognized in a business combination and to eliminate the retrospective accounting for those adjustments. We adopted this standard on January 1, 2016. The adoption of this standard did not have a material impact on our consolidated results of operations, financial position or cash flows. Pending. The following ASUs have been issued but not yet adopted: In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” in an effort to improve revenue recognition practices across entities and industries. The ASU introduces a single, principles-based revenue recognition model which centers on the core principle of an entity recognizing revenue in a manner that depicts the transfer of goods and services to customers at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. Since its release, the FASB has issued multiple amendments clarifying and/or amending ASU No. 2014-09. We have substantially completed a review of contracts with customers in relation to the requirements of ASU No. 2014-09. While we have not identified any material difference in the amount or timing of revenue recognition for the categories we have reviewed to date, our evaluation is not complete and we have not concluded on the overall impacts of adopting this standard. In addition, we are in the process of implementing appropriate changes to our business processes, systems and controls to support the recognition and disclosure requirements under the new standard. ASU No. 2014-09 is effective for us on January 1, 2018 and allows for either full retrospective or modified retrospective adoption. In July 2015, the FASB issued ASU No. 2015-11, “Inventory (Topic 330): Simplifying the Measurement of Inventory,” which simplifies the subsequent measurement of inventory by requiring inventory to be measured at the lower of cost and net realizable value. This ASU is effective for us January 1, 2017 and is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In January 2016, the FASB issued ASU No. 2016-01, “Financial Instruments—Overall (Topic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities,” which amends the classification and measurement of financial instruments. Changes primarily affect the accounting for equity investments, financial liabilities under the fair value option, and the presentation and disclosure requirements for financial instruments. This ASU is effective for us on January 1, 2018. Early adoption is not permitted. We are currently evaluating this ASU and its potential impact on us. In February 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842),” to improve the financial reporting around leasing transactions. The new guidance requires companies to begin recording assets and liabilities arising from those leases classified as operating leases under previous guidance. Furthermore, the new guidance will require significant additional disclosures about the amount, timing and uncertainty of cash flows from leases. Topic 842 retains a distinction between finance leases and operating leases. The classification criteria for distinguishing between finance leases and operating leases are substantially similar to the classification criteria for distinguishing between capital leases and operating leases in previous guidance. The result of retaining a distinction between finance leases and operating leases is that under the lessee accounting model in Topic 842, the effect of leases in the statement of comprehensive income and the statement of cash flows is largely unchanged from previous guidance. This ASU is effective for us January 1, 2019. We are currently evaluating this ASU and its potential impact on us. In March 2016, the FASB issued ASU No. 2016-05, “Derivatives and Hedging (Topic 815): Effect of Derivative Contract Novations on Existing Hedge Accounting Relationships,” which clarifies the hedge accounting impact when there is a change in one of the counterparties to the derivative contract (i.e. novation). This ASU is effective for us January 1, 2017. This ASU is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In March 2016, the FASB issued ASU No. 2016-06, “Derivatives and Hedging (Topic 815): Contingent Put and Call Options in Debt Instruments,” which simplifies the embedded derivative analysis for debt instruments containing contingent call or put options. This ASU is effective for us January 1, 2017. This ASU is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In March 2016, the FASB issued ASU No. 2016-07, “Investments—Equity Method and Joint Ventures (Topic 323): Simplifying the Transition to the Equity Method of Accounting,” which eliminates the requirement to apply the equity method of accounting retrospectively when a reporting entity obtains significant influence over a previously held investment. This ASU is effective for us January 1, 2017. This ASU is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In March 2016, the FASB issued ASU No. 2016-09, “Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting,” which simplifies several aspects of the accounting for share-based payment award transactions. This update requires classification changes for certain tax cash flows within the statement of cash flows and requires all excess tax benefits and tax deficiencies to be recorded through the income statement. In addition, the update provides an accounting policy election around forfeitures and raises the threshold for liability classification of share-based awards withheld for tax withholding requirements. This ASU is effective for us on January 1, 2017. This ASU is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” to replace the incurred loss impairment methodology with a methodology that reflects expected credit losses and requires the consideration of a broader range of reasonable and supportable information to inform credit loss estimates. This ASU is effective for us on January 1, 2020. We are currently evaluating this ASU and its potential impact on us. In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments,” to provide guidance on specific cash flow issues with the objective of reducing the existing diversity in practice. This ASU is effective for us on January 1, 2018. We are currently evaluating this ASU and its potential impact on us. In October 2016, the FASB issued ASU No. 2016-16, “Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory,” to improve the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. This ASU is effective for us on January 1, 2018. We are currently evaluating this ASU and its potential impact on us. In October 2016, the FASB issued ASU No. 2016-17, “Consolidation (Topic 810): Interests Held through Related Parties That Are under Common Control,” to amend the consolidation guidance on how a reporting entity that is the single decision maker of a VIE should treat indirect interests in the entity held through related parties that are under common control with the reporting entity when determining whether it is the primary beneficiary of that VIE. This ASU is effective for us on January 1, 2017. This ASU is not expected to have a material impact on our consolidated results of operations, financial position or cash flows. In November 2016, the FASB issued ASU No. 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash,” to address the diversity in the classification and presentation of changes in restricted cash and restricted cash equivalents on the statement of cash flows. The update requires that restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. This ASU is effective for us on January 1, 2018. We are currently evaluating this ASU and its potential impact on us. In January 2017, the FASB issued ASU No. 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business,” which revises the definition of a business. This ASU is effective for us on January 1, 2018. We are currently evaluating this ASU and its potential impact on us. In January 2017, the FASB issued No. ASU 2017-04, “Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” to simplify the subsequent measurement of goodwill. The guidance eliminates Step 2 from the goodwill impairment test which required computing an implied fair value to measure the amount of the goodwill impairment. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. This ASU is effective for us on January 1, 2020. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are currently evaluating this ASU and its potential impact on us. 2015 . The following ASUs were adopted during 2015 and the effect of such adoption has been presented in the accompanying Consolidated Financial Statements: In April 2014, the FASB issued ASU No. 2014-08, “Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity.” This ASU revises the definition of discontinued operations by limiting discontinued operations reporting to disposals of components of an entity that represent strategic shifts that have or will have a major effect on an entity’s operations and financial results, removing the lack of continuing involvement criteria and requiring discontinued operations reporting for the disposal of an equity method investment that meets the definition of discontinued operations. The update also requires expanded disclosures for discontinued operations, and disclosure of pretax profit or loss of certain individually significant components of an entity that do not qualify for discontinued operations reporting. This ASU was effective for us on January 1, 2015 and did not have a material impact on our consolidated results of operations, financial position or cash flows. In April 2015, the FASB issued ASU No. 2015-03, “Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of the related debt liability, rather than as a deferred charge asset. We adopted this standard on December 31, 2015. The adoption of this ASU resulted in the presentation of $46 million of debt issuance costs as a reduction of Long-term Debt on our December 31, 2015 Consolidated Balance Sheet. In November 2015, the FASB issued ASU No. 2015-17, “Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes . ” This ASU simplifies the balance sheet presentation of deferred income taxes by requiring deferred tax liabilities and assets to be classified as noncurrent in a classified balance sheet. We adopted this standard on December 31, 2015 and applied it prospectively. The adoption of this ASU did not have a material impact on our consolidated results of operations, financial position, or cash flows. 2014 . There were no significant accounting pronouncements issued during 2014 that had a material impact on our consolidated results of operations, financial position or cash flows.
Earnings Per Share, Policy	Basic earnings per common share (EPS) is computed by dividing net income from controlling interests by the weighted-average number of common shares outstanding during the period. Diluted EPS is computed by dividing net income from controlling interests by the diluted weighted-average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if securities or other agreements to issue common stock, such as stock options, stock-based performance unit awards and phantom stock awards, were exercised, settled or converted into common stock. Weighted-average shares used to calculate diluted EPS includes the effect of certain options and restricted stock awards.
Sabal Trail Transmission, LLC
Variable Interest Entity [Line Items]
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	Sabal Trail is a VIE due to insufficient equity at risk to finance its activities. We determined that we are the primary beneficiary because we direct the activities of Sabal Trail that most significantly impact its economic performance and we consolidate Sabal Trail in our financial statements.
Valley Crossing Pipeline, LLC
Variable Interest Entity [Line Items]
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	We are the primary beneficiary because we direct the activities of Valley Crossing that most significantly impact its economic performance. Accordingly, we consolidate Valley Crossing in our financial statements.
Nexus Transmission, LLC
Variable Interest Entity [Line Items]
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	Nexus is a VIE due to insufficient equity at risk to finance its activities. We determined that we are not the primary beneficiary because the power to direct the activities of Nexus that most significantly impact its economic performance is shared. Nexus is accounted for under the equity method of accounting.

Business Segments (Tables)

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Business Segment Data	Business Segment Data Unaffiliated Revenues Intersegment Revenues Total Operating Revenues Depreciation and Amortization Segment EBITDA/ Consolidated Earnings before Income Taxes Capital and Investment Expenditures Assets (in millions) 2016 Spectra Energy Partners $ 2,533 $ — $ 2,533 $ 316 $ 1,909 $ 2,585 $ 21,813 Distribution 1,370 — 1,370 181 473 788 6,132 Western Canada Transmission & Processing 1,005 15 1,020 227 387 410 6,374 Field Services — — — — (40 ) — 1,621 Total reportable segments 4,908 15 4,923 724 2,729 3,783 35,940 Other 8 63 71 50 (126 ) 91 1,073 Eliminations — (78 ) (78 ) — — — (171 ) Depreciation and amortization — — — — 774 — — Interest expense — — — — 594 — — Interest income and other (a) — — — — 1 — — Total consolidated $ 4,916 $ — $ 4,916 $ 774 $ 1,236 $ 3,874 $ 36,842 2015 Spectra Energy Partners $ 2,455 $ — $ 2,455 $ 297 $ 1,905 $ 2,007 $ 18,983 Distribution 1,527 — 1,527 176 473 544 5,209 Western Canada Transmission & Processing 1,242 43 1,285 243 491 360 5,909 Field Services — — — — (461 ) — 1,660 Total reportable segments 5,224 43 5,267 716 2,408 2,911 31,761 Other 10 63 73 48 (384 ) 61 1,226 Eliminations — (106 ) (106 ) — — — (64 ) Depreciation and amortization — — — — 764 — — Interest expense — — — — 636 — — Interest income and other (a) — — — — (3 ) — — Total consolidated $ 5,234 $ — $ 5,234 $ 764 $ 621 $ 2,972 $ 32,923 2014 Spectra Energy Partners $ 2,269 $ — $ 2,269 $ 290 $ 1,669 $ 1,241 $ 17,850 Distribution 1,843 — 1,843 192 552 427 6,055 Western Canada Transmission & Processing 1,781 121 1,902 271 754 473 6,913 Field Services — — — — 217 — 1,345 Total reportable segments 5,893 121 6,014 753 3,192 2,141 32,163 Other 10 62 72 43 (58 ) 146 1,893 Eliminations — (183 ) (183 ) — — — (58 ) Depreciation and amortization — — — — 796 — — Interest expense — — — — 679 — — Interest income and other (a) — — — — 6 — — Total consolidated $ 5,903 $ — $ 5,903 $ 796 $ 1,665 $ 2,287 $ 33,998
Geographic Data	Geographic Data U.S. Canada Consolidated (in millions) 2016 Consolidated revenues $ 2,461 $ 2,455 $ 4,916 Consolidated long-lived assets 20,156 11,997 32,153 2015 Consolidated revenues 2,389 2,845 5,234 Consolidated long-lived assets 17,549 10,979 28,528 2014 Consolidated revenues 2,212 3,691 5,903 Consolidated long-lived assets 15,834 12,715 28,549

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2016
Regulated Operations [Abstract]
Regulatory Assets and Liabilities	The following items are reflected in the consolidated balance sheets. All regulatory assets and liabilities are excluded from rate base unless otherwise noted below. Recovery/Refund Period December 31, 2016 2015 (in millions) Regulatory Assets Under-recovery of fuel costs (c) — $ 6 $ 41 Other — 71 73 Total Regulatory Assets—Current (a) 77 114 Net regulatory asset related to income taxes (d,e) 2 years - remaining life of asset 1,397 1,215 Project development costs (d) Through 2036 9 9 Vacation accrual (d) Various 23 23 Deferred debt expense/premium (d) Various 18 23 Other Various 27 13 Total Regulatory Assets—Non Current (b) 1,474 1,283 Total Regulatory Assets $ 1,551 $ 1,397 Regulatory Liabilities Gas purchase costs (c) — $ 10 $ 48 Other (d) — 66 32 Total Regulatory Liabilities—Current (a) 76 80 Removal costs (d) Exceeds remaining life of asset 293 258 Pipeline rate credit Life of associated liability 23 24 Other (d) Various 42 23 Total Regulatory Liabilities—Non Current (b) 358 305 Total Regulatory Liabilities $ 434 $ 385 ________ (a) Included in Inventory, Fuel Tracker, Current Assets—Other, Taxes Accrued or Current Liabilities—Other. (b) Included in Regulatory Assets and Deferred Debits or Deferred Credits and Other Liabilities—Regulatory and Other. (c) Includes costs settled in cash annually through gas commodity and transportation rates in accordance with FERC and/or OEB gas tariffs. (d) All or a portion of the balance is included in rate base. (e) All amounts are expected to be included in future rate filings.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Tax Expense Components	Income Tax Expense Components 2016 2015 2014 (in millions) Current income taxes Federal $ (1 ) $ — $ 1 State (8 ) 13 3 Foreign 27 60 (10 ) Total current income taxes 18 73 (6 ) Deferred income taxes Federal 258 145 335 State (20 ) (18 ) (17 ) Foreign (40 ) (39 ) 70 Total deferred income taxes 198 88 388 Total income tax expense $ 216 $ 161 $ 382
Earnings from Continuing Operations before Income Taxes	Earnings before Income Taxes 2016 2015 2014 (in millions) Domestic $ 1,010 $ 636 $ 1,108 Foreign 226 (15 ) 557 Total earnings before income taxes $ 1,236 $ 621 $ 1,665
Reconciliation of Income Tax Expense at U.S. Federal Statutory Tax Rate to Actual Income Tax Expense from Continuing Operations	Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to Actual Income Tax Expense 2016 2015 2014 (in millions) Income tax expense, computed at the statutory rate of 35% $ 433 $ 217 $ 583 State income tax, net of federal income tax effect 17 12 25 Tax differential on foreign earnings (71 ) (44 ) (125 ) Noncontrolling interests (114 ) (92 ) (70 ) Valuation allowance (11 ) 1 2 Goodwill impairment — 91 — Revaluation of accumulated deferred state taxes (18 ) (12 ) (25 ) Other items, net (20 ) (12 ) (8 ) Total income tax expense $ 216 $ 161 $ 382 Effective tax rate 17.5 % 25.9 % 22.9 %
Net Deferred Income Tax Liability Components	Net Deferred Income Tax Liability Components December 31, 2016 2015 (in millions) Deferred credits and other liabilities $ 279 $ 275 Net operating loss carryforward 256 295 Other 45 36 Total deferred income tax assets 580 606 Valuation allowance (16 ) (27 ) Net deferred income tax assets 564 579 Investments and other assets (1,516 ) (1,605 ) Accelerated depreciation rates (4,428 ) (4,035 ) Regulatory assets and deferred debits (389 ) (384 ) Total deferred income tax liabilities (6,333 ) (6,024 ) Total net deferred income tax liabilities (a) $ (5,769 ) $ (5,445 )
Reconciliation of Gross Unrecognized Income Tax Benefits	Reconciliation of Gross Unrecognized Income Tax Benefits 2016 2015 2014 (in millions) Balance at beginning of period $ 82 $ 50 $ 76 Increases related to prior year tax positions 15 10 10 Decreases related to prior year tax positions (2 ) (1 ) (6 ) Increases related to current year tax positions 1 30 1 Lapse of statute of limitations (22 ) (4 ) (30 ) Foreign currency translation 1 (3 ) (1 ) Balance at end of period $ 75 $ 82 $ 50

Earnings per Common Share (Tabl

Earnings per Common Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Basic and Diluted EPS Calculations	The following table presents our basic and diluted EPS calculations: 2016 2015 2014 (in millions, except per-share amounts) Net income—controlling interests $ 693 $ 196 $ 1,082 Weighted-average common shares outstanding Basic 694 671 671 Diluted 696 672 672 Basic and diluted earnings per common share $ 1.00 $ 0.29 $ 1.61

Accumulated Other Comprehensi43

Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table presents the net of tax changes in AOCI by component, excluding amounts attributable to noncontrolling interests: Foreign Currency Translation Adjustments Pension and Post-retirement Benefit Plan Obligations Gas Purchase Contract Hedges Other Total Accumulated Other Comprehensive Income (Loss) (in millions) December 31, 2014 $ 1,016 $ (351 ) $ (3 ) $ — $ 662 Other AOCI activity (937 ) 5 — 1 (931 ) December 31, 2015 79 (346 ) (3 ) 1 (269 ) Other AOCI activity 147 (24 ) 3 (3 ) 123 December 31, 2016 $ 226 $ (370 ) $ — $ (2 ) $ (146 )

Inventory (Tables)

Inventory (Tables)	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Components of Inventory	The components of inventory are as follows: December 31, 2016 2015 (in millions) Natural gas $ 183 $ 217 NGLs — 23 Materials and supplies 70 67 Total inventory $ 253 $ 307

Investments in and Loans to U45

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2016
Investments in and Advances to Affiliates, Schedule of Investments [Abstract]
Investments in and Loans to Unconsoliated Affiliates	Investments in and Loans to Unconsolidated Affiliates December 31, 2016 December 31, 2015 Domestic International Total Domestic International Total (in millions) Spectra Energy Partners $ 1,127 $ — $ 1,127 $ 904 $ — $ 904 Distribution — 11 11 — 11 11 Western Canada Transmission & Processing — 21 21 — 17 17 Field Services 1,621 — 1,621 1,660 — 1,660 Total $ 2,748 $ 32 $ 2,780 $ 2,564 $ 28 $ 2,592
Equity in Earnings of Unconsolidated Affiliates	Equity in Earnings of Unconsolidated Affiliates 2016 2015 2014 Domestic International Total Domestic International Total Domestic International Total (in millions) Spectra Energy Partners $ 134 $ — $ 134 $ 167 $ — $ 167 $ 133 $ — $ 133 Distribution — 1 1 — 1 1 — 1 1 Western Canada Transmission & Processing — 3 3 — 2 2 — 1 1 Field Services (41 ) — (41 ) (461 ) — (461 ) 217 — 217 Other — — — 1 — 1 9 — 9 Total $ 93 $ 4 $ 97 $ (293 ) $ 3 $ (290 ) $ 359 $ 2 $ 361
Summarized Combined Financial Information of Unconsolidated Affiliates	Summarized Combined Financial Information of Unconsolidated Affiliates (Presented at 100%) Statements of Operations 2016 2015 2014 DCP Midstream Other Total DCP Midstream Other Total DCP Midstream Other Total (in millions) Operating revenues $ 6,937 $ 494 $ 7,431 $ 7,420 $ 767 $ 8,187 $ 14,013 $ 744 $ 14,757 Operating expenses 6,771 176 6,947 8,227 288 8,515 13,262 319 13,581 Operating income (loss) 166 318 484 (807 ) 479 (328 ) 751 425 1,176 Net income (loss) 81 260 341 (843 ) 393 (450 ) 536 332 868 Net income (loss) attributable to members’ interests (75 ) 260 185 (929 ) 393 (536 ) 288 332 620 Balance Sheets December 31, 2016 December 31, 2015 DCP Midstream Other Total DCP Midstream Other Total (in millions) Current assets $ 1,484 $ 191 $ 1,675 $ 800 $ 498 $ 1,298 Non-current assets 12,610 3,824 16,434 13,094 3,265 16,359 Current liabilities (1,646 ) (126 ) (1,772 ) (896 ) (387 ) (1,283 ) Non-current liabilities (5,554 ) (1,680 ) (7,234 ) (5,894 ) (1,679 ) (7,573 ) Equity—total 6,894 2,209 9,103 7,104 1,697 8,801 Equity—noncontrolling interests (2,270 ) — (2,270 ) (2,404 ) — (2,404 ) Equity—controlling interests $ 4,624 $ 2,209 $ 6,833 $ 4,700 $ 1,697 $ 6,397

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2016
Variable Interest Entities [Abstract]
Schedule of Variable Interest Entities	The following table summarizes the assets and liabilities of Sabal Trail and Valley Crossing: Consolidated Balance Sheets Caption December 31, December 31, (in millions) Assets Current assets $ 165 $ 118 Net property, plant and equipment 2,084 773 Regulatory assets and deferred debits 79 25 Total Assets $ 2,328 $ 916 Liabilities and Equity Current liabilities $ 382 $ 84 Equity 1,946 832 Total Liabilities and Equity $ 2,328 $ 916

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Components and Activity within Goodwill	The following table presents activity within goodwill on a segment basis: Spectra Energy Partners Distribution Western Canada Transmission & Processing Total (in millions) December 31, 2014 $ 3,244 $ 759 $ 711 $ 4,714 Impairment of goodwill — — (333 ) (333 ) Foreign currency translation (12 ) (110 ) (105 ) (227 ) December 31, 2015 3,232 649 273 4,154 Foreign currency translation 2 17 8 27 December 31, 2016 $ 3,234 $ 666 $ 281 $ 4,181
Goodwill Amounts Originating from Acquisition of Westcoast Energy Inc.	The following remaining goodwill amounts originating from the acquisition of Westcoast in 2002 are included as segment assets within “Other” in the segment data presented in Note 4: December 31, 2016 2015 (in millions) Distribution $ 664 $ 646 Western Canada Transmission & Processing 252 246

Marketable Securities and Res48

Marketable Securities and Restricted Funds (Tables)	12 Months Ended
	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Available for Sale Securities	AFS Securities. AFS securities are as follows: Estimated Fair Value December 31, 2016 2015 (in millions) Corporate debt securities (a) $ 8 $ 31 Canadian equity securities (b) 27 — Total available-for-sale securities $ 35 $ 31 ___________________________________ (a) Amounts related to certain construction projects. (b) Amounts related to restricted funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements. Our AFS securities are classified on the Consolidated Balance Sheets as follows: Estimated Fair Value December 31, 2016 2015 (in millions) Restricted funds Investments and other assets—other $ 35 $ 11 Non-restricted funds Current assets—other — 20 Total available-for-sale securities $ 35 $ 31
Held to Maturity Marketable Securities	HTM Securities. HTM securities are as follows: Estimated Fair Value December 31, Description Consolidated Balance Sheets Caption 2016 2015 (in millions) Bankers acceptances Current assets—other $ 20 $ 30 Canadian government securities Current assets—other 23 24 Money market securities Current assets—other 3 3 Canadian government securities Investments and other assets—other 39 50 Bankers acceptances Investments and other assets—other — 12 Total held-to-maturity securities $ 85 $ 119

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property Plant and Equipment	Estimated Useful Life December 31, 2016 2015 (years) (in millions) Plant Natural gas transmission 13–100 $ 17,421 $ 15,690 Natural gas distribution 25–60 2,880 2,651 Gathering and processing facilities 10–40 4,106 4,178 Natural gas storage 10–122 2,193 2,137 Crude oil transportation and storage 5–75 1,321 1,206 Land rights and rights of way 10–122 642 591 Other buildings and improvements 2–75 142 149 Equipment 3–75 305 301 Vehicles 3–15 103 102 Land — 153 138 Construction in process — 3,499 1,919 Software 3–15 438 439 Other 3–82 352 342 Total property, plant and equipment 33,555 29,843 Total accumulated depreciation (6,925 ) (6,527 ) Total accumulated amortization (422 ) (398 ) Total net property, plant and equipment $ 26,208 $ 22,918
Estimated Amortization Expense for Next Five Years	Estimated amortization expense for the next five years follows: Estimated Amortization Expense (in millions) 2017 $ 82 2018 80 2019 58 2020 36 2021 27

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2016
Asset Retirement Obligation Disclosure [Abstract]
Reconciliation of Changes in Asset Retirement Obligation Liabilities	Reconciliation of Changes in Asset Retirement Obligation Liabilities 2016 2015 (in millions) Balance at beginning of year $ 418 $ 400 Accretion expense 20 17 Revisions in estimated cash flows (32 ) 72 Asset dispositions (6 ) — Foreign currency exchange impact 11 (62 ) Liabilities settled (6 ) (9 ) Balance at end of year (a) $ 405 $ 418 ________ (a) Amounts included in Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets.

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Summary of Debt and Related Terms	December 31, 2016 2015 Spectra Energy Capital, LLC (in millions) 6.20% senior unsecured notes due April 2018 $ 500 $ 500 6.75% senior unsecured notes due July 2018 150 150 Variable-rate senior unsecured term loan due November 2018 300 300 8.00% senior unsecured notes due October 2019 500 500 5.65% senior unsecured notes due March 2020 300 300 3.30% senior unsecured notes due March 2023 650 650 6.75% senior unsecured notes due February 2032 240 240 7.50% senior unsecured notes due September 2038 250 250 Total Spectra Energy Capital, LLC Debt 2,890 2,890 SEP SEP 2.95% senior unsecured notes due June 2016 — 250 SEP 2.95% senior unsecured notes due September 2018 500 500 SEP variable-rate senior unsecured term loan due November 2018 400 400 SEP 4.60% senior unsecured notes due June 2021 250 250 SEP 4.75% senior unsecured notes due March 2024 1,000 1,000 SEP 3.50% senior unsecured notes due March 2025 500 500 SEP 3.375% senior unsecured notes due October 2026 600 — SEP 5.95% senior unsecured notes due September 2043 400 400 SEP 4.50% senior unsecured notes due March 2045 700 500 Texas Eastern 6.00% senior unsecured notes due September 2017 400 400 Texas Eastern 4.125% senior unsecured notes due December 2020 300 300 Texas Eastern 2.80% senior unsecured notes due October 2022 500 500 Texas Eastern 7.00% senior unsecured notes due July 2032 450 450 Algonquin 3.51% senior notes due July 2024 350 350 East Tennessee Natural Gas, LLC 3.10% senior notes due December 2024 200 200 Express-Platte 6.09% senior secured notes due January 2020 110 110 Express-Platte 7.39% subordinated secured notes due 2017 to 2019 12 42 Total SEP Debt 6,672 6,152 Westcoast 3.28% medium-term notes due January 2016 — 181 8.50% debentures due September 2018 112 108 5.60% medium-term notes due January 2019 223 217 9.90% debentures due January 2020 74 72 4.57% medium-term notes due July 2020 186 181 3.883% medium-term notes due October 2021 112 108 3.12% medium-term notes due December 2022 186 181 3.43% medium-term notes due September 2024 260 253 8.85% debentures due July 2025 112 108 8.80% medium-term notes due November 2025 18 18 3.77% medium-term notes due December 2025 223 217 7.30% debentures due December 2026 93 90 6.75% medium-term notes due December 2027 112 108 7.15% medium-term notes due March 2031 149 145 4.791% medium-term notes due October 2041 149 145 M&N Canada 6.90% senior secured notes due 2017 to 2019 58 75 M&N Canada 4.34% senior secured notes due 2017 to 2019 28 47 Other 2 2 Total Westcoast Debt $ 2,097 $ 2,256 December 31, 2016 2015 Union Gas (in millions) 4.64% medium-term notes due June 2016 $ — $ 145 9.70% debentures due November 2017 93 90 5.35% medium-term notes due April 2018 149 145 8.75% debentures due August 2018 93 90 8.65% senior debentures due October 2018 56 54 2.76% medium-term notes due June 2021 149 145 4.85% medium-term notes due April 2022 93 90 3.79% medium-term notes due July 2023 186 181 3.19% medium-term notes due September 2025 149 145 8.65% debentures due November 2025 93 90 2.81% medium-term note debentures due June 2026 186 — 5.46% medium-term notes due September 2036 123 119 6.05% medium-term notes due September 2038 223 216 5.20% medium-term notes due July 2040 186 181 4.88% medium-term notes due June 2041 223 217 4.20% medium-term notes due June 2044 371 361 3.80% medium-term note debentures due June 2046 186 — Total Union Gas Debt 2,559 2,269 Total Long-term debt principal (including current maturities) 14,218 13,567 Change in fair value of debt hedged 10 22 Unamortized debt discount, net (20 ) (22 ) Unamortized capitalized debt issuance costs (50 ) (46 ) Other unamortized items 3 4 Total other non-principal amounts (57 ) (42 ) Commercial paper (a,c) 1,453 1,112 Capital Leases 14 19 Total debt (including capital lease obligations) (b) 15,628 14,656 Current maturities of long-term debt (551 ) (652 ) Commercial paper (a,c) (1,453 ) (1,112 ) Total long-term debt (including capital lease obligations) $ 13,624 $ 12,892 ______ (a) The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015 . (b) As of December 31, 2016 and 2015 , respectively, $4,904 million and $4,681 million of debt was denominated in Canadian dollars. (c) Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015 .
Annual Maturities	December 31, 2016 (in millions) 2017 $ 548 2018 2,290 2019 751 2020 970 2021 510 Thereafter 9,163 Total long-term debt, including current maturities (a) $ 14,232 __________ (a) Excludes commercial paper of $1,453 million . Includes capital leases of $14 million .
Available Credit Facilities and Restrictive Debt Covenants	Available Credit Facilities and Restrictive Debt Covenants Expiration Total Commercial Paper Outstanding at December 31, 2016 Available (in millions) Spectra Energy Capital, LLC Multi-year syndicated (a) 2021 $ 1,000 $ 631 $ 369 364-day syndicated (a) 2017 2,000 — 2,000 SEP (b) 2021 2,500 574 1,926 Westcoast (c) 2021 298 — 298 Union Gas (d) 2021 521 248 273 Total $ 6,319 $ 1,453 $ 4,866 __________________ (a) Revolving credit facilities contain a covenant requiring the Spectra Energy consolidated debt-to-total capitalization ratio, as defined in the agreements, to not exceed 65% . Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 56.3% at December 31, 2016 . (b) Revolving credit facility contains a covenant that requires SEP to maintain a ratio of total Consolidated Indebtedness-to-Consolidated EBITDA, as defined in the agreement, of 5.0 to 1 or less. As of December 31, 2016 , this ratio was 3.8 to 1. (c) U.S. dollar equivalent at December 31, 2016 . The revolving credit facility is 400 million Canadian dollars and contains a covenant that requires the Westcoast non-consolidated debt-to-total capitalization ratio to not exceed 75% . The ratio was 33.2% at December 31, 2016 . (d) U.S. dollar equivalent at December 31, 2016 . The revolving credit facility is 700 million Canadian dollars and contains a covenant that requires the Union Gas debt-to-total capitalization ratio to not exceed 75% and a provision which requires Union Gas to repay all borrowings under the facility for a period of two days during the second quarter of each year. The ratio was 69.0% at December 31, 2016 .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring Basis with Fair Value Hierarchy Levels	The following presents, for each of the fair value hierarchy levels, assets and liabilities that are measured and recorded at fair value on a recurring basis: Description Consolidated Balance Sheet Caption December 31, 2016 Total Level 1 Level 2 Level 3 (in millions) Corporate debt securities Cash and cash equivalents $ 191 $ — $ 191 $ — Interest rate swaps Current assets—other 1 — 1 — Corporate debt securities Investments and other assets—other 8 — 8 — Interest rate swaps Investments and other assets—other 23 — 23 — Canadian equity securities Investments and other assets—other 27 27 — — Total Assets $ 250 $ 27 $ 223 $ — Description Consolidated Balance Sheet Caption December 31, 2015 Total Level 1 Level 2 Level 3 (in millions) Corporate debt securities Cash and cash equivalents $ 137 $ — $ 137 $ — Corporate debt securities Current assets—other 20 — 20 — Commodity derivatives Current assets—other 36 — — 36 Commodity derivatives Investments and other assets—other 5 — — 5 Corporate debt securities Investments and other assets—other 11 — 11 — Interest rate swaps Investments and other assets—other 37 — 37 — Total Assets $ 246 $ — $ 205 $ 41
Changes in Level 3 Assets and Liabilities that are Measured at Fair Value on a Recurring Basis using Significant Unobservable Inputs	The following presents changes in Level 3 assets and liabilities that are measured at fair value on a recurring basis using significant unobservable inputs: 2016 2015 (in millions) Derivative assets Fair value, beginning of period $ 41 $ 78 Total gains (losses): Included in earnings (7 ) 43 Included in other comprehensive income 1 (10 ) Purchases (1 ) (3 ) Settlements (34 ) (67 ) Fair value, end of period $ — $ 41 Unrealized gains (losses) relating to instruments held at the end of the period $ — $ (19 )
Fair Value of Financial Instruments Recorded and Carried at Book Value	The fair values of financial instruments that are recorded and carried at book value are summarized in the following table. Judgment is required in interpreting market data to develop the estimates of fair value. These estimates are not necessarily indicative of the amounts we could have realized in current markets. December 31, 2016 2015 Book Value Approximate Fair Value Book Value Approximate Fair Value (in millions) Note receivable, noncurrent (a) $ 71 $ 71 $ 71 $ 71 Long-term debt, including current maturities (b) 14,218 15,168 13,567 13,891 __________ (a) Included within Investments in and Loans to Unconsolidated Affiliates. (b) Excludes commercial paper, capital leases, unamortized items and fair value hedge carrying value adjustments.

Risk Management and Hedging A53

Risk Management and Hedging Activities (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Portfolio Carrying Value	Derivative Portfolio Carrying Value as of December 31, 2016 Maturities in 2017 Maturities in 2018 Maturities in 2019 Maturities in 2020 and Thereafter Total Carrying Value (in millions) Derivatives designated as hedging instruments Interest rate swaps $ 1 $ 8 $ — $ 15 $ 24 Total derivatives designated as hedging instruments 1 8 — 15 24 Total derivative instruments $ 1 $ 8 $ — $ 15 $ 24
Commodity Derivative Assets and Liabilities Offsetting Table	At December 31, 2015 , we had commodity mark-to-market derivatives outstanding that had netting or rights of offset arrangements as follows: December 31, 2015 Gross Amounts Gross Amounts Offset Net Amount Presented in the Consolidated Balance Sheets Description (in millions) Assets $ 104 $ 63 $ 41 Liabilities 63 63 —
Commodity derivative impact	Information regarding the impacts of commodity derivatives on our Consolidated Statements of Operations is as follows: Derivatives Consolidated Statements of Operations Caption 2016 2015 2014 (in millions) Commodity derivatives Sales of natural gas liquids $ 8 $ 40 $ 93
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	Information about our interest rate swaps that had netting or rights of offset arrangements is as follows: December 31, 2016 December 31, 2015 Gross Amounts Presented in the Consolidated Balance Sheets Amounts Not Offset in the Consolidated Balance Sheets Net Amount Gross Amounts Presented in the Consolidated Balance Sheets Amounts Not Offset in the Consolidated Balance Sheets Net Amount Description (in millions) Assets $ 24 $ — $ 24 $ 37 $ — $ 37

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Lease Payments Under Operating Leases	The following is a summary of future minimum lease payments under operating leases which at inception had noncancellable terms of more than one year. We had no material capital lease commitments as of December 31, 2016 or 2015 . Long-term Operating Leases (in millions) 2017 $ 39 2018 38 2019 38 2020 34 2021 31 Thereafter 151 Total future minimum lease payments $ 331

Effects of Changes in Noncont55

Effects of Changes in Noncontrolling Interests Ownership Effects of Changes in Noncontrolling Interests Ownership (Tables)	12 Months Ended
	Dec. 31, 2016
Effects of changes in Noncontrolling Interest [Abstract]
Effect of Issuances of SEP Units	The following table presents the effects of changes in our ownership interests in non-100%-owned consolidated subsidiaries: 2016 2015 2014 (in millions) Net income—controlling interests $ 693 $ 196 $ 1,082 Increase (decrease) in additional paid-in capital resulting from issuances/retirements of SEP units (a) 31 (105 ) 49 Total net income—controlling interests and changes in equity—controlling interests $ 724 $ 91 $ 1,131 ________________ (a) See Note 2 for further discussion.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Components of Pre-Tax Stock Based Compensation Expense in Continuing Operations	We recorded pre-tax stock-based compensation expense as follows, the components of which are described further below: 2016 2015 2014 (in millions) Phantom awards $ 25 $ 11 $ 14 Performance awards 27 18 13 Stock Options 1 — — Total $ 53 $ 29 $ 27
Stock Awards Activity	Awards Activity Performance Awards Phantom Awards Units Weighted Average Grant Date Fair Value Units Weighted Average Grant Date Fair Value (thousands) (thousands) Outstanding at December 31, 2015 1,702 $ 39 1,212 $ 28 Granted 594 53 543 29 Vested (687 ) 38 (504 ) 32 Forfeited (259 ) 37 (51 ) 27 Outstanding at December 31, 2016 1,350 49 1,200 39 Awards expected to vest 1,302 49 1,168 39
Stock Option Activity	Stock Option Activity Options Weighted- Average Exercise Price Weighted- Average Remaining Life Aggregate Intrinsic Value (in thousands) (in years) (in millions) Outstanding at December 31, 2015 958 $ 26 1.2 $ — Granted 925 28 Exercised (875 ) 26 Forfeited or expired (33 ) 28 Outstanding at December 31, 2016 975 28 8.4 13 Exercisable at December 31, 2016 86 26 0.5 1
Performance awards
Weighted Average Assumptions	Weighted-Average Assumptions for Stock-Based Performance Awards 2016 2015 2014 Risk-free rate of return 0.9% 1.1% 0.7% Expected life 3 years 3 years 3 years Expected volatility—Spectra Energy 24% 18% 20% Expected volatility—peer group 19%-69% 13%-27% 14%–32%
Stock options
Weighted Average Assumptions	Weighted-Average Assumptions for Option Pricing 2016 Risk-free rate of return 1.4% Expected life 6 years Expected volatility 22.7% Expected dividend yield 5.7%

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Amounts Recognized in Accumulated Other Comprehensive Income	Amounts Recognized in Accumulated Other Comprehensive Income U.S. Canada December 31, December 31, 2016 2015 2016 2015 (in millions) Net actuarial loss $ 167 $ 156 $ 348 $ 330 Prior service cost — — 3 5 Total amount recognized in AOCI $ 167 $ 156 $ 351 $ 335
Assumptions Used for Benefits Accounting	Assumptions Used for Pension Benefits Accounting U.S. Canada 2016 2015 2014 2016 2015 2014 Benefit Obligations Discount rate 4.11 % 4.58 % 4.10 % 3.81 % 4.03 % 4.00 % Salary increase 4.00 4.00 4.00 3.00 3.00 3.25 Net Periodic Benefit Cost Discount rate 4.58 4.10 4.31 4.03 4.00 4.81 Salary increase 4.00 4.00 4.61 3.00 3.25 3.25 Expected long-term rate of return on plan assets 7.50 8.00 8.00 7.15 7.40 7.40
Assumed Health Care Cost Trend Rates	Assumed Health Care Cost Trend Rates U.S. Canada 2016 2015 2016 2015 Health care cost trend rate assumed for next year 7.00% 7.00% 5.00% 5.50% Rate to which the cost trend is assumed to decline 5.00% 5.00% 5.00% 5.00% Year that the rate reaches the ultimate trend rate 2021 2020 2017 2017
Sensitivity to Changes in Assumed Health Care Cost Trend Rates	Sensitivity to Changes in Assumed Health Care Cost Trend Rates U.S. Canada 1% Point Increase 1% Point Decrease 1% Point Increase 1% Point Decrease (in millions) Effect on total service and interest costs $ — $ — $ 1 $ — Effect on post-retirement benefit obligations 8 (7 ) 5 (4 )
Qualified pension plans
Changes in Level 3 Assets That are Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The following presents changes in Level 3 assets that are measured at fair value on a recurring basis using significant unobservable inputs: U.S. 2016 2015 (in millions) Fair value, beginning of period $ 55 $ 53 Gain included in other comprehensive income 8 2 Fair value, end of period $ 63 $ 55
Pension Plans, Defined Benefit
Change in Projected Benefit Obligation and Change in Fair Value of Plan Assets	Change in Projected Benefit Obligation and Change in Fair Value of Plan Assets U.S. Canada 2016 2015 2016 2015 (in millions) Change in Projected Benefit Obligation Projected benefit obligation, beginning of period $ 571 $ 586 $ 1,034 $ 1,202 Service cost 19 19 28 28 Interest cost 25 24 43 43 Actuarial loss (gain) 21 (18 ) 30 (3 ) Participant contributions — — 5 5 Benefits paid (41 ) (40 ) (48 ) (47 ) Settlement effect — — (13 ) — Foreign currency translation effect — — 31 (194 ) Projected benefit obligation, end of period 595 571 1,110 1,034 Change in Fair Value of Plan Assets Plan assets, beginning of period 532 551 908 1,050 Actual return on plan assets 41 (1 ) 55 52 Benefits paid (41 ) (40 ) (48 ) (47 ) Employer contributions 22 22 17 22 Plan participants’ contributions — — 5 5 Expected non-investment expenses — — (3 ) (3 ) Settlement effect — — (11 ) — Foreign currency translation effect — — 26 (171 ) Plan assets, end of period 554 532 949 908 Net amount recognized $ (41 ) $ (39 ) $ (161 ) $ (126 ) Accumulated Benefit Obligation $ 569 $ 549 $ 1,041 $ 967 U.S. Canada 2016 2015 2016 2015 (in millions) Net amount recognized Current Liabilities—Other $ (2 ) $ (2 ) $ (6 ) $ (5 ) Deferred Credits and Other Liabilities—Regulatory and Other (39 ) (37 ) (175 ) (142 ) Investments and Other Assets—Other — — 20 21 Total net amount recognized $ (41 ) $ (39 ) $ (161 ) $ (126 )
Components of Net Periodic Cost	Components of Net Periodic Pension Costs U.S. Canada 2016 2015 2014 2016 2015 2014 (in millions) Net Periodic Pension Cost Service cost benefit earned $ 19 $ 19 $ 19 $ 31 $ 31 $ 29 Interest cost on projected benefit obligation 25 24 24 43 43 52 Expected return on plan assets (39 ) (42 ) (39 ) (64 ) (65 ) (69 ) Amortization of prior service cost — — — 1 1 2 Amortization of loss 7 10 13 18 25 22 Curtailment effect — — — 1 — — Settlement effect — — — 1 — — Net periodic pension cost 12 11 17 31 35 36 Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Current year actuarial loss 18 25 8 39 10 93 Amortization of actuarial loss (7 ) (10 ) (13 ) (18 ) (25 ) (22 ) Amortization of prior service credit — — — (1 ) (1 ) (2 ) Curtailment effect — — — (1 ) — — Settlement effect — — — (3 ) — — Total recognized in other comprehensive income 11 15 (5 ) 16 (16 ) 69 Total Recognized in Net Periodic Pension Cost and Other Comprehensive Income $ 23 $ 26 $ 12 $ 47 $ 19 $ 105
Pension Plans, Defined Benefit | Qualified pension plans
Plan Assets Allocation	Qualified Pension Plan Assets U.S. Canada Asset Category Target Allocation December 31, Target Allocation December 31, 2016 2015 2016 2015 U.S. equity securities 23 % 22 % 22 % 15 % 16 % 18 % Canadian equity securities — — — 23 28 24 Other equity securities 10 9 10 15 15 13 Fixed income securities 57 58 57 39 41 45 Other investments 10 11 11 8 — — Total 100 % 100 % 100 % 100 % 100 % 100 % The following table summarizes the fair values of pension plan assets recorded at each fair value hierarchy level, as determined in accordance with the valuation techniques described in Note 19: U.S. Canada Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 (in millions) December 31, 2016 Cash and cash equivalents $ 3 $ 3 $ — $ — $ 3 $ 3 $ — $ — Equity securities 171 171 — — 561 266 295 — Fixed income securities 317 317 — — 385 385 — — Other 63 — — 63 — — — — Total $ 554 $ 491 $ — $ 63 $ 949 $ 654 $ 295 $ — December 31, 2015 Cash and cash equivalents $ 2 $ 2 $ — $ — $ 3 $ 3 $ — $ — Equity securities 171 171 — — 501 221 280 — Fixed income securities 304 304 — — 404 404 — — Other 55 — — 55 — — — — Total $ 532 $ 477 $ — $ 55 $ 908 $ 628 $ 280 $ —
Expected Benefit Payments	Expected Benefit Payments U.S. Canada (in millions) 2017 $ 104 $ 49 2018 46 51 2019 48 53 2020 47 55 2021 49 57 Thereafter 231 313
U.S. and Canada Other Post-Retirement Benefits
Change in Projected Benefit Obligation and Change in Fair Value of Plan Assets	Other Post-Retirement Benefit Plans—Change in Projected Benefit Obligation and Fair Value of Plan Assets U.S. Canada 2016 2015 2016 2015 (in millions) Change in Benefit Obligation Accumulated post-retirement benefit obligation, beginning of period $ 166 $ 172 $ 107 $ 133 Service cost 1 1 3 4 Interest cost 8 7 4 5 Plan participants’ contributions 3 3 — — Actuarial loss (gain) 4 1 (5 ) (11 ) Medicare subsidy receivable 1 2 — — Benefits paid (18 ) (20 ) (4 ) (4 ) Plan change 10 — — — Curtailment effect — — (1 ) — Foreign currency translation effect — — 4 (20 ) Accumulated post-retirement benefit obligation, end of period 175 166 108 107 Change in Fair Value of Plan Assets Plan assets, beginning of period 88 92 — — Actual return on plan assets 5 1 — — Benefits paid (18 ) (20 ) (4 ) (4 ) Employer contributions 1 12 4 4 Plan participants’ contributions 3 3 — — Plan assets, end of period 79 88 — — Net amount recognized (a) $ (96 ) $ (78 ) $ (108 ) $ (107 ) _______ (a) Recognized primarily in Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets.
Amounts Recognized in Accumulated Other Comprehensive Income	Other Post-Retirement Benefit Plans—Amounts Recognized in Accumulated Other Comprehensive Income U.S. Canada December 31, December 31, 2016 2015 2016 2015 (in millions) Prior service cost (credit) $ 9 $ — $ (2 ) $ (3 ) Net actuarial loss (gain) 7 3 (4 ) 1 Total amount recognized in AOCI $ 16 $ 3 $ (6 ) $ (2 )
Components of Net Periodic Cost	U.S. Canada 2016 2015 2014 2016 2015 2014 (in millions) Other Post-Retirement Benefit Plans—Components of Net Periodic Benefit Cost Service cost benefit earned $ 1 $ 1 $ 1 $ 3 $ 4 $ 4 Interest cost on accumulated post-retirement benefit obligation 8 7 8 4 5 6 Expected return on plan assets (5 ) (6 ) (5 ) — — — Amortization of prior service cost (credit) 1 — — (1 ) (1 ) (1 ) Amortization of loss — — 1 — — — Curtailment effect — — — (1 ) — — Net periodic other post-retirement benefit cost 5 2 5 5 8 9 Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net prior service cost 10 — — — — — Current year actuarial loss (gain) 4 7 (9 ) (5 ) (11 ) 6 Amortization of actuarial loss — — (1 ) — — — Amortization of prior service cost (credit) (1 ) — — 1 1 1 Total recognized in other comprehensive income 13 7 (10 ) (4 ) (10 ) 7 Total recognized in net periodic benefit cost and other comprehensive income $ 18 $ 9 $ (5 ) $ 1 $ (2 ) $ 16
Assumptions Used for Benefits Accounting	Other Post-Retirement Benefits Plans—Assumptions Used for Benefits Accounting U.S. Canada 2016 2015 2014 2016 2015 2014 Benefit Obligations Discount rate 4.05 % 4.53 % 4.08 % 3.81 % 4.03 % 4.00 % Salary increase 4.00 4.00 4.00 3.00 3.00 3.25 Net Periodic Benefit Cost Discount rate 4.53 4.08 4.46 4.03 4.00 4.83 Salary increase 4.00 4.00 4.61 3.00 3.25 3.25 Expected return on plan assets 6.33 6.83 6.98 N/A N/A N/A
Plan Assets Allocation	Other Post-Retirement Plan Assets U.S. Asset Category December 31, 2016 2015 Cash and cash equivalents 5 % 3 % Equity securities 39 45 Fixed income securities 48 46 Other assets 8 6 Total 100 % 100 % The following table summarizes the fair values of the other post-retirement plan assets recorded at each fair value hierarchy level as determined in accordance with the valuation techniques described in Note 19: U.S. VEBA I and VEBA II Trusts Master Trust Total Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 (in millions) December 31, 2016 Cash and cash equivalents $ 4 $ 4 $ — $ — $ — $ — $ — $ — Equity securities 16 — 16 — 15 15 — — Fixed income securities 10 — 10 — 28 28 — — Other investments — — — — 6 — — 6 Total $ 30 $ 4 $ 26 $ — $ 49 $ 43 $ — $ 6 December 31, 2015 Cash and cash equivalents $ 3 $ 3 $ — $ — $ — $ — $ — $ — Equity securities 24 — 24 — 15 15 — — Fixed income securities 14 — 14 — 26 26 — — Other investments — — — — 5 — — 5 Total $ 41 $ 3 $ 38 $ — $ 46 $ 41 $ — $ 5
Expected Benefit Payments	The following benefit payments and subsidies are expected to be paid (or received) over each of the next five years and thereafter. Benefit Payments Medicare Part D Subsidy Receipts U.S. Canada U.S. (in millions) 2017 $ 16 $ 4 $ (2 ) 2018 16 4 (2 ) 2019 16 4 (2 ) 2020 15 4 (2 ) 2021 15 5 (2 ) Thereafter 63 26 (8 )
U.S. Postretirement Benefit Plan
Changes in Level 3 Assets That are Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs	The following presents changes in Level 3 assets that are measured at fair value on a recurring basis using significant unobservable inputs: U.S. 2016 2015 (in millions) Fair value, beginning of period $ 5 $ 4 Unrealized gain included in other comprehensive income 1 1 Fair value, end of period $ 6 $ 5

Consolidating Financial Infor58

Consolidating Financial Information (Tables)	12 Months Ended
	Dec. 31, 2016
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Statement of Operations	Spectra Energy Corp Condensed Consolidating Statement of Operations Year Ended December 31, 2016 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Total operating revenues $ — $ — $ 4,919 $ (3 ) $ 4,916 Total operating expenses 7 4 3,323 (3 ) 3,331 Loss on sales of other assets and other, net — — (26 ) — (26 ) Operating income (loss) (7 ) (4 ) 1,570 — 1,559 Earnings from equity investments — — 97 — 97 Equity in earnings of consolidated subsidiaries 671 1,166 — (1,837 ) — Other income and expenses, net 1 — 173 — 174 Interest expense — 236 358 — 594 Earnings before income taxes 665 926 1,482 (1,837 ) 1,236 Income tax expense (benefit) (28 ) 255 (11 ) — 216 Net income 693 671 1,493 (1,837 ) 1,020 Net income—noncontrolling interests — — 327 — 327 Net income—controlling interests $ 693 $ 671 $ 1,166 $ (1,837 ) $ 693 Spectra Energy Corp Condensed Consolidating Statement of Operations Year Ended December 31, 2015 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Total operating revenues $ — $ — $ 5,237 $ (3 ) $ 5,234 Total operating expenses 6 (4 ) 3,806 (3 ) 3,805 Gain on sales of other assets and other, net — — 4 — 4 Operating income (loss) (6 ) 4 1,435 — 1,433 Loss from equity investments — — (290 ) — (290 ) Equity in earnings of consolidated subsidiaries 161 573 — (734 ) — Other income and expenses, net — 1 113 — 114 Interest expense — 244 392 — 636 Earnings before income taxes 155 334 866 (734 ) 621 Income tax expense (benefit) (41 ) 173 29 — 161 Net income 196 161 837 (734 ) 460 Net income—noncontrolling interests — — 264 — 264 Net income—controlling interests $ 196 $ 161 $ 573 $ (734 ) $ 196 Spectra Energy Corp Condensed Consolidating Statement of Operations Year Ended December 31, 2014 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Total operating revenues $ — $ — $ 5,906 $ (3 ) $ 5,903 Total operating expenses 6 1 3,974 (3 ) 3,978 Loss on sales of other assets and other, net — — (1 ) — (1 ) Operating income (loss) (6 ) (1 ) 1,931 — 1,924 Earnings from equity investments — — 361 — 361 Equity in earnings of consolidated subsidiaries 1,054 1,651 — (2,705 ) — Other income and expenses, net (2 ) 9 52 — 59 Interest expense — 253 426 — 679 Earnings before income taxes 1,046 1,406 1,918 (2,705 ) 1,665 Income tax expense (benefit) (36 ) 352 66 — 382 Net income 1,082 1,054 1,852 (2,705 ) 1,283 Net income—noncontrolling interests — — 201 — 201 Net income—controlling interests $ 1,082 $ 1,054 $ 1,651 $ (2,705 ) $ 1,082
Condensed Consolidating Statement of Comprehensive Income	Spectra Energy Corp Condensed Consolidating Statements of Comprehensive Income (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Year Ended December 31, 2016 Net income $ 693 $ 671 $ 1,493 $ (1,837 ) $ 1,020 Other comprehensive income (loss) (15 ) — 141 — 126 Total comprehensive income, net of tax 678 671 1,634 (1,837 ) 1,146 Less: comprehensive income—noncontrolling interests — — 330 — 330 Comprehensive income—controlling interests $ 678 $ 671 $ 1,304 $ (1,837 ) $ 816 Year Ended December 31, 2015 Net income $ 196 $ 161 $ 837 $ (734 ) $ 460 Other comprehensive income (loss) (14 ) 1 (931 ) — (944 ) Total comprehensive income (loss), net of tax 182 162 (94 ) (734 ) (484 ) Less: comprehensive income—noncontrolling interests — — 251 — 251 Comprehensive income (loss)—controlling interests $ 182 $ 162 $ (345 ) $ (734 ) $ (735 ) Year Ended December 31, 2014 Net income $ 1,082 $ 1,054 $ 1,852 $ (2,705 ) $ 1,283 Other comprehensive income (loss) 9 1 (596 ) — (586 ) Total comprehensive income, net of tax 1,091 1,055 1,256 (2,705 ) 697 Less: comprehensive income—noncontrolling interests — — 194 — 194 Comprehensive income—controlling interests $ 1,091 $ 1,055 $ 1,062 $ (2,705 ) $ 503
Condensed Consolidating Balance Sheet	Spectra Energy Corp Condensed Consolidating Balance Sheet December 31, 2016 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Cash and cash equivalents $ — $ 10 $ 295 $ — $ 305 Receivables—consolidated subsidiaries 2 — 2 (4 ) — Notes receivable—current—consolidated subsidiaries — — 388 (388 ) — Receivables—other 1 1 1,001 — 1,003 Other current assets 16 2 446 — 464 Total current assets 19 13 2,132 (392 ) 1,772 Investments in and loans to unconsolidated affiliates — — 2,780 — 2,780 Investments in consolidated subsidiaries 8,403 18,579 — (26,982 ) — Advances receivable—consolidated subsidiaries — 720 — (720 ) — Notes receivable—consolidated subsidiaries — — 2,800 (2,800 ) — Goodwill — — 4,181 — 4,181 Other assets 86 18 289 — 393 Net property, plant and equipment — — 26,208 — 26,208 Regulatory assets and deferred debits 3 10 1,495 — 1,508 Total Assets $ 8,511 $ 19,340 $ 39,885 $ (30,894 ) $ 36,842 Accounts payable $ 3 $ 2 $ 823 $ — $ 828 Accounts payable—consolidated subsidiaries — 4 — (4 ) — Commercial paper — 631 822 — 1,453 Short-term borrowings—consolidated subsidiaries — 388 — (388 ) — Taxes accrued 2 — 84 — 86 Current maturities of long-term debt — — 551 — 551 Other current liabilities 92 51 844 — 987 Total current liabilities 97 1,076 3,124 (392 ) 3,905 Long-term debt — 2,886 10,738 — 13,624 Advances payable—consolidated subsidiaries 499 — 221 (720 ) — Notes payable—consolidated subsidiaries — 2,800 — (2,800 ) — Deferred credits and other liabilities 758 4,175 2,279 — 7,212 Preferred stock of subsidiaries — — 562 — 562 Equity Controlling interests 7,157 8,403 18,579 (26,982 ) 7,157 Noncontrolling interests — — 4,382 — 4,382 Total equity 7,157 8,403 22,961 (26,982 ) 11,539 Total Liabilities and Equity $ 8,511 $ 19,340 $ 39,885 $ (30,894 ) $ 36,842 Spectra Energy Corp Condensed Consolidating Balance Sheet December 31, 2015 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated Cash and cash equivalents $ — $ 1 $ 212 $ — $ 213 Receivables—consolidated subsidiaries 15 6 13 (34 ) — Notes receivable—current—consolidated subsidiaries — — 387 (387 ) — Receivables—other 2 — 804 — 806 Other current assets 25 — 604 — 629 Total current assets 42 7 2,020 (421 ) 1,648 Investments in and loans to unconsolidated affiliates — — 2,592 — 2,592 Investments in consolidated subsidiaries 13,919 19,161 — (33,080 ) — Advances receivable—consolidated subsidiaries — 5,273 1,326 (6,599 ) — Notes receivable—consolidated subsidiaries — — 2,800 (2,800 ) — Goodwill — — 4,154 — 4,154 Other assets 41 27 242 — 310 Net property, plant and equipment — — 22,918 — 22,918 Regulatory assets and deferred debits 3 3 1,295 — 1,301 Total Assets $ 14,005 $ 24,471 $ 37,347 $ (42,900 ) $ 32,923 Accounts payable $ 2 $ 3 $ 506 $ — $ 511 Accounts payable—consolidated subsidiaries 4 28 2 (34 ) — Commercial paper — 481 631 — 1,112 Short-term borrowings—consolidated subsidiaries — 387 — (387 ) — Taxes accrued 5 — 73 — 78 Current maturities of long-term debt — — 652 — 652 Other current liabilities 102 48 889 — 1,039 Total current liabilities 113 947 2,753 (421 ) 3,392 Long-term debt — 2,891 10,001 — 12,892 Advances payable—consolidated subsidiaries 6,599 — — (6,599 ) — Notes payable—consolidated subsidiaries — 2,800 — (2,800 ) — Deferred credits and other liabilities 767 3,914 2,087 — 6,768 Preferred stock of subsidiaries — — 339 — 339 Equity Controlling interests 6,526 13,919 19,161 (33,080 ) 6,526 Noncontrolling interests — — 3,006 — 3,006 Total equity 6,526 13,919 22,167 (33,080 ) 9,532 Total Liabilities and Equity $ 14,005 $ 24,471 $ 37,347 $ (42,900 ) $ 32,923
Condensed Consolidating Statement of Cash Flows	Spectra Energy Corp Condensed Consolidating Statement of Cash Flows Year Ended December 31, 2016 (In millions) Spectra Energy Corp (a) Spectra Capital (a) Non-Guarantor Subsidiaries (a) Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 693 $ 671 $ 1,493 $ (1,837 ) $ 1,020 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Depreciation and amortization — — 799 — 799 Loss on sales of other assets and other, net — — 26 — 26 Earnings from equity investments — — (97 ) — (97 ) Equity in earnings of consolidated subsidiaries (671 ) (1,166 ) — 1,837 — Distributions from equity investments — — 111 — 111 Other (51 ) 268 (50 ) — 167 Net cash provided by (used in) operating activities (29 ) (227 ) 2,282 — 2,026 CASH FLOWS FROM INVESTING ACTIVITIES Capital expenditures — — (3,623 ) — (3,623 ) Investments in and loans to unconsolidated affiliates — — (251 ) — (251 ) Purchase of intangible, net — — (80 ) — (80 ) Dispositions — — 207 — 207 Purchases of held-to-maturity securities — — (633 ) — (633 ) Proceeds from sales and maturities of held-to-maturity securities — — 670 — 670 Purchases of available-for-sale securities — — (738 ) — (738 ) Proceeds from sales and maturities of available-for-sale securities — — 735 — 735 Distributions from equity investments — — 50 — 50 Advances from (to) affiliates (50 ) 118 — (68 ) — Distribution to equity investment — — (148 ) — (148 ) Other changes in restricted funds — — (20 ) — (20 ) Other — — 1 — 1 Net cash provided by (used in) investing activities (50 ) 118 (3,830 ) (68 ) (3,830 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from the issuance of long-term debt — — 1,183 — 1,183 Payments for the redemption of long-term debt — — (652 ) — (652 ) Net increase in commercial paper — 150 169 — 319 Distributions to noncontrolling interests — — (246 ) — (246 ) Contributions from noncontrolling interests — — 743 — 743 Proceeds from the issuances of Spectra Energy common stock 879 — — — 879 Proceeds from the issuance of SEP common units — — 579 — 579 Proceeds from the issuance of Westcoast preferred stock — — 229 — 229 Dividends paid on common stock (1,127 ) — — — (1,127 ) Distributions and advances from (to) affiliates 316 (23 ) (361 ) 68 — Other 11 (9 ) (19 ) — (17 ) Net cash provided by financing activities 79 118 1,625 68 1,890 Effect of exchange rate changes on cash — — 6 — 6 Net increase in cash and cash equivalents — 9 83 — 92 Cash and cash equivalents at beginning of period — 1 212 — 213 Cash and cash equivalents at end of period $ — $ 10 $ 295 $ — $ 305 ________ (a) Excludes the effects of $6,416 million of non-cash equitizations of advances receivable owed to Spectra Capital and Spectra Energy Corp. Spectra Energy Corp Condensed Consolidating Statement of Cash Flows Year Ended December 31, 2015 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 196 $ 161 $ 837 $ (734 ) $ 460 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Depreciation and amortization — — 778 — 778 Impairment charges — — 349 — 349 Gain on sales of other assets and other, net — — (4 ) — (4 ) Earnings from equity investments — — 290 — 290 Equity in earnings of consolidated subsidiaries (161 ) (573 ) — 734 — Distributions from equity investments — — 161 — 161 Other 187 33 (7 ) — 213 Net cash provided by (used in) operating activities 222 (379 ) 2,404 — 2,247 CASH FLOWS FROM INVESTING ACTIVITIES Capital expenditures — — (2,848 ) — (2,848 ) Investments in and loans to unconsolidated affiliates — — (124 ) — (124 ) Purchases of held-to-maturity securities — — (668 ) — (668 ) Proceeds from sales and maturities of held-to-maturity securities — — 695 — 695 Purchases of available-for-sale securities — — (95 ) — (95 ) Proceeds from sales and maturities of available-for-sale securities — — 87 — 87 Distributions from equity investments — — 451 — 451 Distribution to equity investment — — (248 ) — (248 ) Advances from (to) affiliates (240 ) 296 — (56 ) — Other changes in restricted funds — — (33 ) — (33 ) Other — — 1 — 1 Net cash provided by (used in) investing activities (240 ) 296 (2,782 ) (56 ) (2,782 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from the issuance of long-term debt — — 1,585 — 1,585 Payments for the redemption of long-term debt — — (285 ) — (285 ) Net increase (decrease) in commercial paper — 83 (522 ) — (439 ) Distributions to noncontrolling interests — — (198 ) — (198 ) Contributions from noncontrolling interests — — 248 — 248 Proceeds from the issuance of SEP common units — — 546 — 546 Proceeds from the issuance of Westcoast preferred stock — — 84 — 84 Dividends paid on common stock (996 ) — — — (996 ) Distributions and advances from (to) affiliates 1,018 — (1,074 ) 56 — Other (4 ) — (1 ) — (5 ) Net cash provided by financing activities 18 83 383 56 540 Effect of exchange rate changes on cash — — (7 ) — (7 ) Net decrease in cash and cash equivalents — — (2 ) — (2 ) Cash and cash equivalents at beginning of period — 1 214 — 215 Cash and cash equivalents at end of period $ — $ 1 $ 212 $ — $ 213 Spectra Energy Corp Condensed Consolidating Statement of Cash Flows Year Ended December 31, 2014 (In millions) Spectra Energy Corp Spectra Capital Non-Guarantor Subsidiaries Eliminations Consolidated CASH FLOWS FROM OPERATING ACTIVITIES Net income $ 1,082 $ 1,054 $ 1,852 $ (2,705 ) $ 1,283 Adjustments to reconcile net income to net cash provided by (used in) operating activities: Depreciation and amortization — — 809 — 809 Loss on sales of other assets and other, net — — 1 — 1 Earnings from equity investments — — (361 ) — (361 ) Equity in earnings of consolidated subsidiaries (1,054 ) (1,651 ) — 2,705 — Distributions from equity investments — — 380 — 380 Other 14 304 (209 ) — 109 Net cash provided by (used in) operating activities 42 (293 ) 2,472 — 2,221 CASH FLOWS FROM INVESTING ACTIVITIES Capital expenditures — — (2,028 ) — (2,028 ) Investments in and loans to unconsolidated affiliates — — (259 ) — (259 ) Purchases of held-to-maturity securities — — (790 ) — (790 ) Proceeds from sales and maturities of held-to-maturity securities — — 815 — 815 Purchases of available-for-sale securities — — (13 ) — (13 ) Proceeds from sales and maturities of available-for-sale securities — — 7 — 7 Distributions from equity investments — — 266 — 266 Advances from affiliates 92 495 — (587 ) — Other changes in restricted funds — — (1 ) — (1 ) Net cash provided by (used in) investing activities 92 495 (2,003 ) (587 ) (2,003 ) CASH FLOWS FROM FINANCING ACTIVITIES Proceeds from the issuance of long-term debt — 300 728 — 1,028 Payments for the redemption of long-term debt — (557 ) (627 ) — (1,184 ) Net increase in commercial paper — 54 520 — 574 Distributions to noncontrolling interests — — (175 ) — (175 ) Contributions from noncontrolling interests — — 145 — 145 Proceeds from the issuance of SEP common units — — 327 — 327 Dividends paid on common stock (925 ) — — — (925 ) Distributions and advances from (to) affiliates 777 (10 ) (1,354 ) 587 — Other 14 — (3 ) — 11 Net cash used in financing activities (134 ) (213 ) (439 ) 587 (199 ) Effect of exchange rate changes on cash — — (5 ) — (5 ) Net increase (decrease) in cash and cash equivalents — (11 ) 25 — 14 Cash and cash equivalents at beginning of period — 12 189 — 201 Cash and cash equivalents at end of period $ — $ 1 $ 214 $ — $ 215

Quarterly Financial Data (Una59

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data	First Quarter Second Quarter Third Quarter Fourth Quarter Total (in millions, except per share amounts) 2016 Operating revenues $ 1,384 $ 1,159 $ 1,075 $ 1,298 $ 4,916 Operating income 494 371 321 373 1,559 Net income 310 221 281 208 1,020 Net income—controlling interests 234 149 195 115 693 Earnings per share (a) Basic and diluted 0.35 0.21 0.28 0.16 1.00 2015 Operating revenues $ 1,623 $ 1,192 $ 1,103 $ 1,316 $ 5,234 Operating income 541 406 389 97 1,433 Net income (loss) 325 80 243 (188 ) 460 Net income (loss)—controlling interests 267 18 174 (263 ) 196 Earnings (loss) per share (a) Basic and diluted 0.40 0.03 0.26 (0.39 ) 0.29 ___________ (a) Quarterly earnings-per-share amounts are stand-alone calculations and may not be additive to full-year amounts due to rounding.

Summary of Operations and Sig60

Summary of Operations and Significant Accounting Policies Business Combination (Details) - Enbridge & Spectra Proposed Merger [Member] - USD ($) $ / shares in Units, $ in Billions	Jan. 01, 2017	Sep. 30, 2016	Jan. 31, 2017	Sep. 02, 2016
Business Acquisition [Line Items]
Business Acquisition, Share Price Premium				11.50%
Enbridge, Inc | Spectra Energy Corp
Business Acquisition [Line Items]
Business Acquisition, Date of Acquisition Agreement		Sep. 2, 2016
Business Acquisition, Shares Conversion Ratio				0.984
Business Acquisition, Share Price				$ 40.33
Scenario, Forecast
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired			43.00%
Scenario, Forecast | Enbridge, Inc
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired			57.00%
Scenario, Forecast | Enbridge, Inc | Spectra Energy Corp
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 28

Summary of Operations and Sig61

Summary of Operations and Significant Accounting Policies (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Significant Accounting Policies [Line Items]
Allowance for funds used during construction	$ 232	$ 143	$ 72
Equity component of allowance for funds used during construction	164	111	53
Interest expense component of allowance for funds used during construction	68	32	19
Goodwill, Impairment Loss	0	333	$ 0
Unamortized Debt Issuance Expense	$ 50	$ 46
Segment Reporting, Disclosure of Major Customers	There were no customers accounting for 10% or more of consolidated revenues during 2016, 2015 or 2014.	There were no customers accounting for 10% or more of consolidated revenues during 2016, 2015 or 2014.	There were no customers accounting for 10% or more of consolidated revenues during 2016, 2015 or 2014.
Other Income and Expenses
Significant Accounting Policies [Line Items]
Foreign currency transaction gains (losses)	$ (1)	$ (6)	$ 3
Restatement Adjustment
Significant Accounting Policies [Line Items]
Unamortized Debt Issuance Expense		46
Accounts Receivable
Significant Accounting Policies [Line Items]
Natural Gas Imbalances	407	291
Current Liabilities—Other
Significant Accounting Policies [Line Items]
Natural Gas Imbalances	$ (382)	(287)
Western Canada Transmission & Processing
Significant Accounting Policies [Line Items]
Goodwill, Impairment Loss		333
Western Canada Transmission & Processing | BC Pipeline and BC Field Services
Significant Accounting Policies [Line Items]
Goodwill, Impairment Loss		270
Western Canada Transmission & Processing | Empress
Significant Accounting Policies [Line Items]
Goodwill, Impairment Loss		$ 63
DCP Midstream, LLC
Significant Accounting Policies [Line Items]
Equity Method Investment, Ownership Percentage	50.00%

Spectra Energy Partners, LP - A

Spectra Energy Partners, LP - Additional Information (Detail) - USD ($)	Oct. 30, 2015	Apr. 30, 2016	Nov. 30, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2015	Dec. 31, 2013
Related Party Transaction [Line Items]
Proceeds from the issuance of Spectra Energy Partners common units				$ 579,000,000	$ 546,000,000	$ 327,000,000
Spectra Energy Partners, LP | Minimum
Related Party Transaction [Line Items]
Potential Proceeds from the issuances of Spectra Energy Partners, LP common units			$ 400,000,000
Spectra Energy Partners, LP | Maximum
Related Party Transaction [Line Items]
Potential Proceeds from the issuances of Spectra Energy Partners, LP common units			$ 1,000,000,000
Spectra Energy Partners, LP | U.S. Asset Dropdown
Related Party Transaction [Line Items]
Limited Partners' Capital Account, Units Issued						4,300,000	17,114
General partner units issued (in shares)						86,000	342
Spectra Energy Partners, LP | Limited Partner | SEP At-the-Market program
Related Party Transaction [Line Items]
Spectra Energy purchase of SEP's common units				12,800,000	12,000,000	6,400,000
Proceeds from the issuance of Spectra Energy Partners common units				$ 579,000,000	$ 546,000,000	$ 327,000,000
Spectra Energy Partners, LP | Limited Partner | Issuance of Common Units | Private Placement
Related Party Transaction [Line Items]
Spectra Energy purchase of SEP's common units		10,400,000
Spectra Energy Partners, LP | Limited Partner | Sand Hills and Southern Hills
Related Party Transaction [Line Items]
Partners' Capital Account, Units, Redeemed	21,560,000
Spectra Energy Partners, LP | General Partner | Issuance of Common Units | SEP At-the-Market program
Related Party Transaction [Line Items]
Spectra Energy purchase of SEP's common units				262,000	245,000	132,000
Spectra Energy Partners, LP | General Partner | Issuance of Common Units | Private Placement
Related Party Transaction [Line Items]
Spectra Energy purchase of SEP's common units		200,000
Spectra Energy Partners, LP | General Partner | Sand Hills and Southern Hills
Related Party Transaction [Line Items]
Partners' Capital Account, Units, Redeemed	440,000
Spectra Energy Partners, LP | Sand Hills and Southern Hills
Related Party Transaction [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	33.30%
Reduction in Quarterly Distributions	$ 4,000,000
Reduction in Yearly Distributions				$ 16,000,000
Spectra Energy Partners, LP | Limited Partner
Related Party Transaction [Line Items]
General Partners' Capital Account Percentage Interest				75.00%
Spectra Energy Partners, LP | General Partner
Related Party Transaction [Line Items]
General Partners' Capital Account Percentage Interest				2.00%		2.00%	2.00%
Steckman Ridge, LP | Spectra Energy Partners, LP | U.S. Asset Dropdown
Related Party Transaction [Line Items]
Business Acquisition, Percentage of Voting Interests NOT acquired								1.00%
Percentage of Voting Rights Contributed						1.00%
Southeast Supply Header | Spectra Energy Partners, LP | U.S. Asset Dropdown
Related Party Transaction [Line Items]
Business Acquisition, Percentage of Voting Interests NOT acquired								25.05%
Percentage of Voting Rights Contributed						24.95%	0.10%

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - USD ($) $ in Millions	Oct. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Effect of transfer of interests in subsidiaries		$ 0	$ 2
Additional Paid-in Capital
Business Acquisition [Line Items]
Effect of transfer of interests in subsidiaries		166	3
Noncontrolling Interests
Business Acquisition [Line Items]
Effect of transfer of interests in subsidiaries		$ (166)	$ (1)
Sand Hills and Southern Hills | Additional Paid-in Capital
Business Acquisition [Line Items]
Effect of transfer of interests in subsidiaries	$ 166
Sand Hills and Southern Hills | Noncontrolling Interests
Business Acquisition [Line Items]
Effect of transfer of interests in subsidiaries	$ (166)
Sand Hills and Southern Hills | Spectra Energy Partners, LP | Limited Partner
Business Acquisition [Line Items]
Partners' Capital Account, Units, Redeemed	21,560,000
Sand Hills and Southern Hills | Spectra Energy Partners, LP | General Partner
Business Acquisition [Line Items]
Partners' Capital Account, Units, Redeemed	440,000
Sand Hills and Southern Hills | Spectra Energy Partners, LP
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	33.30%

Dispositions - Additional Infor

Dispositions - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)	$ 216	$ 161	$ 382
DCP Midstream, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
DCP Midstream, LLC | Sand Hills and Southern Hills
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of Voting Rights Contributed				33.30%
Spectra Energy Partners, LP | Sand Hills and Southern Hills
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired				33.30%
Empress
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Consideration	$ 204
Gain (Loss) on Disposition of Business	(1)
Income tax expense (benefit)	(27)
Empress | Current assets
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Consideration	$ 51

Business Segments - Additional

Business Segments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016reportable_segments
Segment Reporting Information [Line Items]
Number of reportable segments	4
DCP Midstream, LLC
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Phillips Sixty Six | DCP Midstream, LLC
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
DCP Midstream, LLC | DCP Midstream Partners, LP
Segment Reporting Information [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	21.00%

Business Segment - Data (Detail

Business Segment - Data (Detail) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Operating revenues		$ 1,298	$ 1,075	$ 1,159	$ 1,384	$ 1,316	$ 1,103	$ 1,192	$ 1,623	$ 4,916	$ 5,234	$ 5,903
Depreciation and amortization										774	764	796
Interest expense										594	636	679
Interest income and other	[1]									1		6
Interest income and other	[1]										(3)
Earnings Before Income Taxes										1,236	621	1,665
Capital and Investment Expenditures										3,874	2,972	2,287
Assets		36,842				32,923				36,842	32,923	33,998
Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues										(78)	(106)	(183)
Assets		(171)				(64)				(171)	(64)	(58)
Spectra Energy Partners
Segment Reporting Information [Line Items]
Operating revenues										2,533	2,455	2,269
Depreciation and amortization										316	297	290
Earnings Before Interest Taxes Depreciation And Amortization										1,909	1,905	1,669
Capital and Investment Expenditures										2,585	2,007	1,241
Assets		21,813				18,983				21,813	18,983	17,850
Spectra Energy Partners | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues										2,533	2,455	2,269
Spectra Energy Partners | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues										0	0	0
Distribution
Segment Reporting Information [Line Items]
Operating revenues										1,370	1,527	1,843
Depreciation and amortization										181	176	192
Earnings Before Interest Taxes Depreciation And Amortization										473	473	552
Capital and Investment Expenditures										788	544	427
Assets		6,132				5,209				6,132	5,209	6,055
Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues										1,370	1,527	1,843
Distribution | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues										0	0	0
Western Canada Transmission & Processing
Segment Reporting Information [Line Items]
Operating revenues										1,005	1,242	1,781
Depreciation and amortization										227	243	271
Earnings Before Interest Taxes Depreciation And Amortization										387	491	754
Capital and Investment Expenditures										410	360	473
Assets		6,374				5,909				6,374	5,909	6,913
Western Canada Transmission & Processing | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues										1,020	1,285	1,902
Western Canada Transmission & Processing | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues										15	43	121
Field Services
Segment Reporting Information [Line Items]
Earnings Before Interest Taxes Depreciation And Amortization										(40)	(461)	217
Assets		1,621				1,660				1,621	1,660	1,345
Total Reportable Segments
Segment Reporting Information [Line Items]
Operating revenues										4,908	5,224	5,893
Depreciation and amortization										724	716	753
Earnings Before Interest Taxes Depreciation And Amortization										2,729	2,408	3,192
Capital and Investment Expenditures										3,783	2,911	2,141
Assets		35,940				31,761				35,940	31,761	32,163
Total Reportable Segments | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues										4,923	5,267	6,014
Total Reportable Segments | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues										15	43	121
Other
Segment Reporting Information [Line Items]
Operating revenues										8	10	10
Depreciation and amortization										50	48	43
Earnings Before Interest Taxes Depreciation And Amortization										(126)	(384)	(58)
Capital and Investment Expenditures										91	61	146
Assets		$ 1,073				$ 1,226				1,073	1,226	1,893
Other | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues										71	73	72
Other | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues										$ 63	$ 63	$ 62
[1]	Includes foreign currency transaction gains and losses related to segment EBITDA.

Business Segments - Geographic

Business Segments - Geographic Data (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Consolidated revenues	$ 1,298	$ 1,075	$ 1,159	$ 1,384	$ 1,316	$ 1,103	$ 1,192	$ 1,623	$ 4,916	$ 5,234	$ 5,903
Consolidated long-lived assets	32,153				28,528				32,153	28,528	28,549
United States
Segment Reporting Information [Line Items]
Consolidated revenues									2,461	2,389	2,212
Consolidated long-lived assets	20,156				17,549				20,156	17,549	15,834
Canada
Segment Reporting Information [Line Items]
Consolidated revenues									2,455	2,845	3,691
Consolidated long-lived assets	$ 11,997				$ 10,979				$ 11,997	$ 10,979	$ 12,715

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	[1]	$ 77	$ 114
Regulatory Assets, Noncurrent	[2]	1,474	1,283
Regulatory Assets		1,551	1,397
Regulatory Liability, Current	[1]	76	80
Regulatory Liability, Noncurrent	[2]	358	305
Regulatory Liabilities		434	385
Gas purchase costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Current	[3]	10	48
Other
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Current	[4]	66	32
Regulatory Liability, Noncurrent	[4]	42	23
Removal costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Noncurrent	[4]	293	258
Pipeline rate credit
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Noncurrent		23	24
Under-recovery of fuel costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current	[3]	6	41
Other
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Current		71	73
Regulatory Assets, Noncurrent		27	13
Net regulatory asset related to income taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	[4],[5]	1,397	1,215
Project development costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent		9	9
Vacation accrual
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent		23	23
Deferred debt expense/premium
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	[4]	$ 18	$ 23
[1]	Included in Inventory, Fuel Tracker, Current Assets—Other, Taxes Accrued or Current Liabilities—Other.
[2]	Included in Regulatory Assets and Deferred Debits or Deferred Credits and Other Liabilities—Regulatory and Other.
[3]	Includes costs settled in cash annually through gas commodity and transportation rates in accordance with FERC and/or OEB gas tariffs.
[4]	All or a portion of the balance is included in rate base.
[5]	All amounts are expected to be included in future rate filings.

Regulatory Matters - Regulatory

Regulatory Matters - Regulatory Assets and Liabilities Information (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	[1]	$ 1,474	$ 1,283
Regulatory Liability, Noncurrent	[1]	358	305
Regulatory Liability, Current	[2]	76	80
Removal costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Noncurrent	[3]	293	258
Gas purchase costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Current	[4]	10	48
Net regulatory asset related to income taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent	[3],[5]	1,397	1,215
Union Gas Limited | Removal costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Noncurrent		293	258
Union Gas Limited | Gas purchase costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Liability, Current		10	48
Union Gas Limited | Net regulatory asset related to income taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent		344	291
BC Pipeline and BC Field Services | Net regulatory asset related to income taxes
Schedule of Regulatory Assets and Liabilities [Line Items]
Regulatory Assets, Noncurrent		$ 789	$ 727
[1]	Included in Regulatory Assets and Deferred Debits or Deferred Credits and Other Liabilities—Regulatory and Other.
[2]	Included in Inventory, Fuel Tracker, Current Assets—Other, Taxes Accrued or Current Liabilities—Other.
[3]	All or a portion of the balance is included in rate base.
[4]	Includes costs settled in cash annually through gas commodity and transportation rates in accordance with FERC and/or OEB gas tariffs.
[5]	All amounts are expected to be included in future rate filings.

Regulatory Matters - Regulato70

Regulatory Matters - Regulatory Cases (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Regulatory Matters [Line Items]
Regulatory Assets		$ 1,551			$ 1,397
Union Gas Limited | 2014 Demand Side Management Deferrals
Regulatory Matters [Line Items]
Regulatory Assets			$ 9
Union Gas Limited | 2015-2020 DSM Plan: 2016 Draft Rate Order
Regulatory Matters [Line Items]
Regulatory Assets				$ 19
Union Gas Limited | 2015 Annual Deferrals
Regulatory Matters [Line Items]
Regulatory Assets			$ 18
Scenario, Forecast | Union Gas Limited | 2017 DSM approved budget
Regulatory Matters [Line Items]
Regulatory Assets	$ 43

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense Components (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current income taxes
Federal	$ (1)	$ 0	$ 1
State	(8)	13	3
Foreign	27	60	(10)
Total current income taxes	18	73	(6)
Deferred income taxes
Federal	258	145	335
State	(20)	(18)	(17)
Foreign	(40)	(39)	70
Total deferred income taxes	198	88	388
Income Tax Expense	$ 216	$ 161	$ 382

Income Taxes - Earnings from Co

Income Taxes - Earnings from Continuing Operations before Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ 1,010	$ 636	$ 1,108
Foreign	226	(15)	557
Earnings Before Income Taxes	$ 1,236	$ 621	$ 1,665

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense at U.S. Federal Statutory Tax Rate to Actual Income Tax Expense from Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 433	$ 217	$ 583
State income tax, net of federal income tax effect	17	12	25
Tax differential on foreign earnings	(71)	(44)	(125)
Noncontrolling interests	(114)	(92)	(70)
Valuation allowance	(11)	1	2
Goodwill impairment	0	91	0
Revaluation of accumulated deferred state taxes	(18)	(12)	(25)
Other items, net	(20)	(12)	(8)
Total income tax expense	$ 216	$ 161	$ 382
Effective tax rate	17.50%	25.90%	22.90%
Federal Statutory Income Tax Rate	35.00%	35.00%	35.00%

Income Taxes - Net Deferred Inc

Income Taxes - Net Deferred Income Tax Liability Components (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Deferred credits and other liabilities		$ 279	$ 275
Net operating loss carryforward		256	295
Other		45	36
Total deferred income tax assets		580	606
Valuation allowance		(16)	(27)
Net deferred income tax assets		564	579
Investments and other assets		(1,516)	(1,605)
Accelerated depreciation rates		(4,428)	(4,035)
Regulatory assets and deferred debits		(389)	(384)
Total deferred income tax liabilities		(6,333)	(6,024)
Total net deferred income tax liabilities (a)	[1]	$ (5,769)	$ (5,445)
[1]	These amounts are classified as Deferred Credits and Other Liabilities—Deferred Income Taxes in the Consolidated Balance Sheets.

Income Taxes - Reconciliation75

Income Taxes - Reconciliation of Gross Unrecognized Income Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 82	$ 50	$ 76
Increases related to prior year tax positions	15	10	10
Decreases related to prior year tax positions	(2)	(1)	(6)
Increases related to current year tax positions	1	30	1
Lapse of statute of limitations	(22)	(4)	(30)
Foreign currency translation	1
Foreign currency translation		(3)	(1)
Balance at end of period	$ 75	$ 82	$ 50

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Contingency [Line Items]
Unrecognized tax benefits	$ 75	$ 82	$ 50	$ 76
Unrecognized tax benefits that would reduce the annual effective tax rate if recognized in next fiscal year	45
Net increase in gross uncertain tax benefits	7
Uncertain tax benefits, deferred tax liabilities and foreign currency exchange rate fluctuations	6
Uncertain tax benefits, decrease in income tax expense	1
Interest income related to unrecognized tax benefits	(17)	2
Accrued interest and penalties related to unrecognized tax benefits	4	21
Undistributed earnings of foreign subsidiaries	1,800
Minimum
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	20
Maximum
Income Tax Contingency [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	30
Domestic Tax Authority
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	572
Deferred tax asset attributable to the federal net operating loss	200
Operating Loss Carryforwards, Valuation Allowance	9	9
Deferred Tax Asset, Capital Loss Carryforward	$ 27
Domestic Tax Authority | Minimum
Income Tax Contingency [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2021
Subject to examination income tax return fillings, date	2,013
Domestic Tax Authority | Maximum
Income Tax Contingency [Line Items]
Subject to examination income tax return fillings, date	2,015
State
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	$ 399
Deferred tax asset attributable to the state net operating loss carryovers	20
Operating Loss Carryforwards, Valuation Allowance	0	1
Deferred Tax Asset, Capital Loss Carryforward	$ 1
State | Minimum
Income Tax Contingency [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2020
Subject to examination income tax return fillings, date	2,007
State | Maximum
Income Tax Contingency [Line Items]
Subject to examination income tax return fillings, date	2,015
Foreign Country
Income Tax Contingency [Line Items]
Net Operating Loss Carryforward	$ 135
Operating Loss Carryforwards, Valuation Allowance	1	1
Deferred Tax Asset, Capital Loss Carryforward	6
Deferred tax asset attributable to foreign net operating loss	$ 36
Foreign Country | Minimum
Income Tax Contingency [Line Items]
Operating Loss Carryforwards, Expiration Date	Jan. 1, 2026
Subject to examination income tax return fillings, date	2,009
Foreign Country | Maximum
Income Tax Contingency [Line Items]
Subject to examination income tax return fillings, date	2,015
Capital Loss Carryforward | Federal and State Tax Authority
Income Tax Contingency [Line Items]
Capital Loss Carryforward	$ 77
Capital loss carryforward, expiration date	Jan. 1, 2021
Capital Loss Carryforward | Foreign Country
Income Tax Contingency [Line Items]
Capital Loss Carryforward	$ 48
Valuation allowance against deferred tax asset related to foreign capital loss carryforward	$ 6	$ 16

Earnings per Common Share - Opt

Earnings per Common Share - Options or Stock Awards Not Included in EPS (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0	0

Earnings per Common Share - Bas

Earnings per Common Share - Basic and Diluted EPS Calculations (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income—Controlling Interests	$ 115		$ 195		$ 149		$ 234		$ (263)		$ 174		$ 18		$ 267		$ 693		$ 196		$ 1,082
Weighted average common shares, outstanding
Basic (in shares)																	694		671		671
Diluted (in shares)																	696		672		672
Earnings per Common Share, Basic and Diluted	$ 0.16	[1]	$ 0.28	[1]	$ 0.21	[1]	$ 0.35	[1]	$ (0.39)	[1]	$ 0.26	[1]	$ 0.03	[1]	$ 0.40	[1]	$ 1	[1]	$ 0.29	[1]	$ 1.61
[1]	Quarterly earnings-per-share amounts are stand-alone calculations and may not be additive to full-year amounts due to rounding.

Accumulated Other Comprehensi79

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	$ (269)	$ 662
Other AOCI activity	123	(931)
Balance at end of period	(146)	(269)
Foreign Currency Translation Adjustments
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	79	1,016
Other AOCI activity	147	(937)
Balance at end of period	226	79
Pension and Post-retirement Benefit Plan Obligations
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(346)	(351)
Other AOCI activity	(24)	5
Balance at end of period	(370)	(346)
Gas Purchase Contract Hedges
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	(3)	(3)
Other AOCI activity	3	0
Balance at end of period	0	(3)
Other
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Balance at beginning of period	1	0
Other AOCI activity	(3)	1
Balance at end of period	$ (2)	$ 1

Inventory - Components of Inven

Inventory - Components of Inventory (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Natural gas	$ 183	$ 217
NGLs	0	23
Materials and supplies	70	67
Total inventory	$ 253	$ 307

Inventory - Additional Informat

Inventory - Additional Information (Detail) - Western Canada Transmission & Processing - Empress Operations $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Inventories [Line Items]
Inventory Write-down	$ 14
Inventory Write-down, net of tax	$ 10

Investments in and Loans to U82

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions - Additional Information (Detail) - USD ($)	Oct. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Nov. 30, 2015
Schedule of Equity Method Investments [Line Items]
Distributions From Equity Investments		$ 161,000,000	$ 612,000,000	$ 646,000,000
Retained Earnings, Undistributed Earnings from Equity Method Investees		33,000,000	28,000,000
Earnings (loss) from equity investments		97,000,000	(290,000,000)	361,000,000
Goodwill Impairment Recorded by Equity Method Investment		0	333,000,000	0
Impairment charges		0	349,000,000	$ 0
DCP Midstream, LLC | Sand Hills and Southern Hills
Schedule of Equity Method Investments [Line Items]
Percentage of Voting Rights Contributed	33.30%
Sand Hills and Southern Hills | Spectra Energy Partners, LP
Schedule of Equity Method Investments [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	33.30%
Reduction in Quarterly Distributions	$ 4,000,000
Reduction in Yearly Distributions		$ 16,000,000
Spectra Energy Partners, LP | U.S. Asset Dropdown
Schedule of Equity Method Investments [Line Items]
Limited Partners' Capital Account, Units Issued				4,300,000	17,114
General partner units issued (in shares)				86,000	342
Spectra Energy Partners, LP | Sand Hills and Southern Hills | Limited Partner
Schedule of Equity Method Investments [Line Items]
Partners' Capital Account, Units, Redeemed	21,560,000
Spectra Energy Partners, LP | Sand Hills and Southern Hills | General Partner
Schedule of Equity Method Investments [Line Items]
Partners' Capital Account, Units, Redeemed	440,000
DCP Midstream, LLC
Schedule of Equity Method Investments [Line Items]
Goodwill Impairment Recorded by Equity Method Investment			460,000,000
Impairment charges			342,000,000
DCP Midstream, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
DCP Midstream, LLC | Gain from limited partner units issuance
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments		$ 0	2,000,000	$ 73,000,000
DCP Midstream, LLC | Goodwill and Asset Impairment
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments			(231,000,000)
DCP Midstream, LLC | Sand Hills and Southern Hills
Schedule of Equity Method Investments [Line Items]
Percentage of Voting Rights Contributed	33.30%
Southeast Supply Header | Spectra Energy Partners, LP | U.S. Asset Dropdown
Schedule of Equity Method Investments [Line Items]
Percentage of Voting Rights Contributed				24.95%	0.10%
Steckman Ridge, LP | Spectra Energy Partners, LP | U.S. Asset Dropdown
Schedule of Equity Method Investments [Line Items]
Percentage of Voting Rights Contributed				1.00%
Spectra Energy Partners, LP | Limited Partner
Schedule of Equity Method Investments [Line Items]
General Partners' Capital Account Percentage Interest		75.00%
Spectra Energy Partners, LP | General Partner
Schedule of Equity Method Investments [Line Items]
General Partners' Capital Account Percentage Interest		2.00%		2.00%	2.00%
Spectra Energy Partners
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments		$ 134,000,000	167,000,000	$ 133,000,000
Goodwill Impairment Recorded by Equity Method Investment			0
Spectra Energy Partners | Steckman Ridge, LP
Schedule of Equity Method Investments [Line Items]
Loans and Leases Receivable, Related Parties		71,000,000	71,000,000
Interest Income, Related Party		$ 1,000,000	$ 1,000,000	$ 1,000,000
Spectra Energy Partners | Maximum | Steckman Ridge, LP
Schedule of Equity Method Investments [Line Items]
Related Party Loan Due Date		Oct. 1, 2023
Spectra Energy Partners | Gulfstream
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		39.00%
Spectra Energy Partners | Southeast Supply Header
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		39.00%
Spectra Energy Partners | Steckman Ridge, LP
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		39.00%

Investments in and Loans to U83

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions - Investments in and Loans to Unconsolidated Affiliates (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	$ 2,780	$ 2,592
Domestic
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	2,748	2,564
International
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	32	28
Spectra Energy Partners
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	1,127	904
Spectra Energy Partners | Domestic
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	1,127	904
Spectra Energy Partners | International
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	0	0
Distribution
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	11	11
Distribution | Domestic
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	0	0
Distribution | International
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	11	11
Western Canada Transmission & Processing
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	21	17
Western Canada Transmission & Processing | Domestic
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	0	0
Western Canada Transmission & Processing | International
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	21	17
Field Services
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	1,621	1,660
Field Services | Domestic
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	1,621	1,660
Field Services | International
Schedule of Equity Method Investments [Line Items]
Investments in and loans to unconsolidated affiliates	$ 0	$ 0

Investments in and Loans to U84

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions - Equity in Earnings of Unconsolidated Affiliates (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	$ 97	$ (290)	$ 361
Domestic
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	93	(293)	359
International
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	4	3	2
Spectra Energy Partners
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	134	167	133
Spectra Energy Partners | Domestic
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	134	167	133
Spectra Energy Partners | International
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	0	0	0
Distribution
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	1	1	1
Distribution | Domestic
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	0	0	0
Distribution | International
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	1	1	1
Western Canada Transmission & Processing
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	3	2	1
Western Canada Transmission & Processing | Domestic
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	0	0	0
Western Canada Transmission & Processing | International
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	3	2	1
Field Services
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	(41)	(461)	217
Field Services | Domestic
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	(41)	(461)	217
Field Services | International
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	0	0	0
Other
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	0	1	9
Other | Domestic
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	0	1	9
Other | International
Schedule of Equity Method Investments [Line Items]
Earnings (loss) from equity investments	$ 0	$ 0	$ 0

Investments in and Loans to U85

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions - Summarized Statements of Operations of Unconsolidated Affiliates Presented at 100 Percent (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Operating Revenues	$ 7,431	$ 8,187	$ 14,757
Operating Expenses	6,947	8,515	13,581
Operating Income	484	(328)	1,176
Net Income	341	(450)	868
Net Income Attributable to Members' Interests	185	(536)	620
DCP Midstream, LLC
Schedule of Equity Method Investments [Line Items]
Operating Revenues	6,937	7,420	14,013
Operating Expenses	6,771	8,227	13,262
Operating Income	166	(807)	751
Net Income	81	(843)	536
Net Income Attributable to Members' Interests	(75)	(929)	288
Other Affiliates
Schedule of Equity Method Investments [Line Items]
Operating Revenues	494	767	744
Operating Expenses	176	288	319
Operating Income	318	479	425
Net Income	260	393	332
Net Income Attributable to Members' Interests	$ 260	$ 393	$ 332

Investments in and Loans to U86

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions - Summarized Balance Sheets of Unconsolidated Affiliates Presented at 100 Percent (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Current Assets	$ 1,675	$ 1,298
Non-current Assets	16,434	16,359
Current Liabilities	(1,772)	(1,283)
Non-current Liabilities	(7,234)	(7,573)
Equity Method Investment Summarized Financial Information, Equity	9,103	8,801
Equity - Noncontrolling Interests	(2,270)	(2,404)
Equity - Controlling Interests	6,833	6,397
DCP Midstream, LLC
Schedule of Equity Method Investments [Line Items]
Current Assets	1,484	800
Non-current Assets	12,610	13,094
Current Liabilities	(1,646)	(896)
Non-current Liabilities	(5,554)	(5,894)
Equity Method Investment Summarized Financial Information, Equity	6,894	7,104
Equity - Noncontrolling Interests	(2,270)	(2,404)
Equity - Controlling Interests	4,624	4,700
Other Affiliates
Schedule of Equity Method Investments [Line Items]
Current Assets	191	498
Non-current Assets	3,824	3,265
Current Liabilities	(126)	(387)
Non-current Liabilities	(1,680)	(1,679)
Equity Method Investment Summarized Financial Information, Equity	2,209	1,697
Equity - Noncontrolling Interests	0	0
Equity - Controlling Interests	$ 2,209	$ 1,697

Investments in and Loans to U87

Investments in and Loans to Unconsolidated Affiliates and Related Party Transactions - Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Distributions from equity investments				$ 111	$ 161	$ 380
Distribution to equity investment				148	248	0
Gulfstream
Related Party Transaction [Line Items]
Debt Instrument, Face Amount			$ 800
SESH
Related Party Transaction [Line Items]
Debt Instrument, Face Amount						400
Gulfstream
Related Party Transaction [Line Items]
Distributions from equity investments			$ 396
Distribution to equity investment	$ 148	$ 248
SESH
Related Party Transaction [Line Items]
Distributions from equity investments						200
Distribution to equity investment						200
Project Costs
Related Party Transaction [Line Items]
Recovery of Direct Costs				116	139
DCP Midstream, LLC
Related Party Transaction [Line Items]
Accounts Receivable, Related Parties		1		3	1
Distributions from equity investments				0	0	237
DCP Midstream, LLC | Other Revenue, Net
Related Party Transaction [Line Items]
Revenue from Related Parties				2	3	2
DCP Midstream, LLC | Other Revenue, Net | Gas Processing Revenue
Related Party Transaction [Line Items]
Revenue from Related Parties				31	46	79
DCP Midstream, LLC | Transportation, Storage and Processing of Natural Gas
Related Party Transaction [Line Items]
Revenue from Related Parties				1	4	7
DCP Midstream, LLC | Sales of Natural Gas Liquids
Related Party Transaction [Line Items]
Revenue from Related Parties				0	4	7
Other Affiliates
Related Party Transaction [Line Items]
Recovery of Direct Costs				68	28	$ 38
Due from Related Parties		$ 11		$ 21	$ 11

Variable Interest Entities (Det

Variable Interest Entities (Details) - Variable Interest Entity, Primary Beneficiary [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Total Assets	$ 2,328	$ 916
Equity	1,946	832
Total Liabilities and Equity	2,328	916
Current assets
Variable Interest Entity [Line Items]
Total Assets	165	118
Net property, plant and equipment
Variable Interest Entity [Line Items]
Total Assets	2,084	773
Regulatory assets and deferred debits
Variable Interest Entity [Line Items]
Total Assets	79	25
Current Liabilities
Variable Interest Entity [Line Items]
Current liabilities	$ 382	$ 84

Variable Interest Entities - Ad

Variable Interest Entities - Additional Information (Details) - USD ($) $ in Millions	Jan. 01, 2017	Apr. 01, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Contributions from noncontrolling interests			$ 743	$ 248	$ 145
Sabal Trail Transmission, LLC
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage			37.60%
Sabal Trail Transmission, LLC | Scenario, Forecast
Variable Interest Entity [Line Items]
Construction and Development Costs	$ 1,200
Sabal Trail Transmission, LLC | Spectra Energy Partners, LP
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage			50.00%
Sabal Trail Transmission, LLC | Spectra Energy Partners, LP | NextEra
Variable Interest Entity [Line Items]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Sale of Interest by Parent		9.50%
Total consideration received for sale of ownership interest		$ 110
Contributions from noncontrolling interests		$ 102
Valley Crossing Pipeline, LLC | Scenario, Forecast
Variable Interest Entity [Line Items]
Construction and Development Costs	$ 1,400
Nexus Transmission, LLC
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage			37.60%
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount			$ 1,000
Nexus Transmission, LLC | Investments in and loans to unconsolidated affiliates
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets			$ 356	$ 90

Intangible Asset - Additional I

Intangible Asset - Additional Information (Details) - USD ($) $ in Millions	Apr. 01, 2016	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Purchase of intangible				$ 80	$ 0	$ 0
Sabal Trail Transmission, LLC
Finite-Lived Intangible Assets [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage				37.60%
Spectra Energy Partners, LP | Sabal Trail Transmission, LLC
Finite-Lived Intangible Assets [Line Items]
Purchase of intangible		$ 40	$ 48
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage				50.00%
Spectra Energy Partners, LP | Sabal Trail Transmission, LLC | Investments and Other Assets—Other
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross				$ 80
Finite-Lived Intangible Asset, Useful Life				25 years
Spectra Energy Partners, LP | Sabal Trail Transmission, LLC | NextEra
Finite-Lived Intangible Assets [Line Items]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Sale of Interest by Parent	9.50%
Intangible Assets, Reimbursement	$ 8

Goodwill - Components and Activ

Goodwill - Components and Activity within Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Beginning balance	$ 4,154	$ 4,714
Impairment Loss	0	(333)	$ 0
Foreign currency translation	27	(227)
Ending balance	4,181	4,154	4,714
Spectra Energy Partners
Goodwill [Roll Forward]
Beginning balance	3,232	3,244
Impairment Loss		0
Foreign currency translation	2	(12)
Ending balance	3,234	3,232	3,244
Distribution
Goodwill [Roll Forward]
Beginning balance	649	759
Impairment Loss		0
Foreign currency translation	17	(110)
Ending balance	666	649	759
Western Canada Transmission & Processing
Goodwill [Roll Forward]
Beginning balance	273	711
Impairment Loss		(333)
Foreign currency translation	8	(105)
Ending balance	$ 281	$ 273	$ 711

Goodwill - Amounts Originating

Goodwill - Amounts Originating from Acquisition of Westcoast Energy Inc. (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 4,181	$ 4,154	$ 4,714
Distribution
Goodwill [Line Items]
Goodwill	666	649	759
Western Canada Transmission & Processing
Goodwill [Line Items]
Goodwill	281	273	$ 711
Westcoast Energy Inc. | Distribution
Goodwill [Line Items]
Goodwill	664	646
Westcoast Energy Inc. | Western Canada Transmission & Processing
Goodwill [Line Items]
Goodwill	$ 252	$ 246

Goodwill - Impairment of Goodwi

Goodwill - Impairment of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 0	$ 333	$ 0
Western Canada Transmission & Processing
Goodwill [Line Items]
Goodwill, Impairment Loss		333
Western Canada Transmission & Processing | BC Pipeline and BC Field Services
Goodwill [Line Items]
Goodwill, Impairment Loss		270
Western Canada Transmission & Processing | Empress
Goodwill [Line Items]
Goodwill, Impairment Loss		$ 63

Marketable Securities and Res94

Marketable Securities and Restricted Funds - Schedule of Restricted and Non-restricted Available for Sale Securities (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities		$ 35	$ 31
Investments and Other Assets—Other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Restricted, Noncurrent		35	11
Current Assets—Other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Current		0	20
Corporate Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities	[1]	8	31
Canadian equity securities
Schedule of Available-for-sale Securities [Line Items]
Total available-for-sale securities	[2]	$ 27	$ 0
[1]	Amounts related to certain construction projects.
[2]	Amounts related to restricted funds held and collected from customers of Western Canada Transmission & Processing and Express-Platte for Canadian pipeline abandonment in accordance with the NEB’s regulatory requirements.

Marketable Securities and Res95

Marketable Securities and Restricted Funds - Schedule of Restricted and Non-restricted Available for Sale Securities - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Gross Unrealized Gain (Loss)	$ 0	$ 0
Available-for-sale Securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Weighted Average Contractual Maturity Of Outstanding Securities	1 year

Marketable Securities and Res96

Marketable Securities and Restricted Funds - Schedule of Held to Maturity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Total held-to-maturity securities	$ 85	$ 119
Current Assets—Other | Bankers Acceptance
Schedule of Held-to-maturity Securities [Line Items]
Total held-to-maturity securities	20	30
Current Assets—Other | Canadian Government Securities
Schedule of Held-to-maturity Securities [Line Items]
Total held-to-maturity securities	23	24
Current Assets—Other | Money Market Funds
Schedule of Held-to-maturity Securities [Line Items]
Total held-to-maturity securities	3	3
Investments and Other Assets—Other | Bankers Acceptance
Schedule of Held-to-maturity Securities [Line Items]
Total held-to-maturity securities	0	12
Investments and Other Assets—Other | Canadian Government Securities
Schedule of Held-to-maturity Securities [Line Items]
Total held-to-maturity securities	$ 39	$ 50

Marketable Securities and Res97

Marketable Securities and Restricted Funds - Schedule of Held to Maturity Securities - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities, Unrecognized Holding Gain	$ 0	$ 0
Held-to-maturity Securities, Unrecognized Holding Loss	$ 0	$ 0
M&N Canada six point nine zero percent senior secured notes due 2014 to 2019 | Maritimes & Northeast Pipeline Limited Partnership
Schedule of Held-to-maturity Securities [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.90%
Held-to-maturity Securities | Maximum
Schedule of Held-to-maturity Securities [Line Items]
Weighted Average Contractual Maturity Of Outstanding Securities	1 year

Marketable Securities and Res98

Marketable Securities and Restricted Funds - Schedule of Other Restricted Funds - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Current Assets—Other
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Current	$ 27	$ 11
Current Assets—Other | Cash received for Green Investment Fund
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Current	11
Current Assets—Other | Amounts restricted for insurance purposes
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Current	12	11
Current Assets—Other | M&N Canada six point nine zero percent senior secured notes due 2014 to 2019
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Current	4
Investments and Other Assets—Other
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	42	38
Investments and Other Assets—Other | Cash received for Green Investment Fund
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	17
Investments and Other Assets—Other | M&N Canada six point nine zero percent senior secured notes due 2014 to 2019
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	3
Investments and Other Assets—Other | Canadian Pipeline Abandonment Requirement
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	17	24
Investments and Other Assets—Other | Project Costs
Gain (Loss) on Investments [Line Items]
Restricted Cash and Cash Equivalents, Noncurrent	$ 5	$ 14

Marketable Securities and Res99

Marketable Securities and Restricted Funds - Interest Income Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income
Net Investment Income [Line Items]
Investment Income, Interest	$ 3	$ 3	$ 4

Property Plant and Equipment (D

Property Plant and Equipment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 33,555	$ 29,843
Total accumulated depreciation	(6,925)	(6,527)
Total accumulated amortization	(422)	(398)
Net property, plant and equipment	26,208	22,918
Plant | Natural gas transmission
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 17,421	15,690
Plant | Natural gas transmission | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	13 years
Plant | Natural gas transmission | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	100 years
Plant | Natural gas distribution
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 2,880	2,651
Plant | Natural gas distribution | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	25 years
Plant | Natural gas distribution | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	60 years
Plant | Gathering and processing facilities
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 4,106	4,178
Plant | Gathering and processing facilities | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Plant | Gathering and processing facilities | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	40 years
Plant | Natural gas storage
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 2,193	2,137
Plant | Natural gas storage | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Plant | Natural gas storage | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	122 years
Plant | Crude oil transportation and storage
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 1,321	1,206
Plant | Crude oil transportation and storage | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	5 years
Plant | Crude oil transportation and storage | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	75 years
Plant | Land rights and rights of way
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 642	591
Plant | Land rights and rights of way | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	10 years
Plant | Land rights and rights of way | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	122 years
Plant | Other buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 142	149
Plant | Other buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	2 years
Plant | Other buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	75 years
Equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 305	301
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	75 years
Vehicles
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 103	102
Vehicles | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Vehicles | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	15 years
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 153	138
Construction in process
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	3,499	1,919
Software
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 438	439
Software | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Software | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	15 years
Other
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 352	$ 342
Other | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	3 years
Other | Maximum
Property, Plant and Equipment [Line Items]
Estimated Useful Life	82 years

Property, Plant and Equipment E

Property, Plant and Equipment Estimated Amortization Expense for Next Five Years (Detail) $ in Millions	Dec. 31, 2016USD ($)
Estimated Amortization Expense
2,017	$ 82
2,018	80
2,019	58
2,020	36
2,021	$ 27

Property, Plant And Equipment -

Property, Plant And Equipment - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Capital Leases, Balance Sheet, Assets by Major Class, Net	$ 0	$ 0
Percentage of public utilities property plant and equipment regulated with estimated useful lives based on rates approved by regulatory authorities	86.00%
Composite weighted-average depreciation rates	2.66%	2.72%	2.82%
Amortization expense of intangible assets	$ 74	$ 79	$ 74

Asset Retirement Obligations -

Asset Retirement Obligations - Reconciliation of Changes in Asset Retirement Obligation Liabilities (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of year		$ 418	[1]	$ 400
Accretion expense		20		17
Revisions in estimated cash flows		(32)		72
Asset dispositions		(6)		0
Foreign currency exchange impact		11		(62)
Liabilities settled		(6)		(9)
Balance at end of year (a)	[1]	$ 405		$ 418
[1]	Amounts included in Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets.

Asset Retirement Obligations104

Asset Retirement Obligations - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Reconciliation Of Changes In Asset Retirement Obligations [Line Items]
Asset retirement obligation, revision of estimate	$ (32)	$ 72
Spectra Energy Partners
Reconciliation Of Changes In Asset Retirement Obligations [Line Items]
Asset retirement obligation, revision of estimate		$ 32

Debt and Credit Facilities Summ

Debt and Credit Facilities Summary of Debt and Related Terms (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Secured Debt		$ 208
Long-term debt principal (including current maturities)		14,218	$ 13,567
Change in fair value of debt hedged		10	22
Unamortized debt discount, net		(20)	(22)
Unamortized Debt Issuance Expense		(50)	(46)
Other unamortized items		3	4
Total other non-principal amounts		(57)	(42)
Commercial paper	[1],[2]	1,453	1,112
Capital Leases		14	19
Total debt (including capital lease obligations)	[3]	15,628	14,656
Current maturities of long-term debt		(551)	(652)
Commercial paper	[1],[2]	(1,453)	(1,112)
Total long-term debt (including capital lease obligations)		13,624	12,892
Spectra Energy Capital, LLC
Debt Instrument [Line Items]
Long-term debt principal (including current maturities)		2,890	2,890
Spectra Energy Capital, LLC | 6.20% senior unsecured notes due April 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 500	500
Debt Instrument, Interest Rate, Stated Percentage		6.20%
Debt Instrument, Maturity Date, Description		April 2,018
Spectra Energy Capital, LLC | 6.75% senior unsecured notes due July 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 150	150
Debt Instrument, Interest Rate, Stated Percentage		6.75%
Debt Instrument, Maturity Date, Description		July 2,018
Spectra Energy Capital, LLC | Variable-rate senior unsecured term loan due November 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 300	300
Debt Instrument, Maturity Date, Description		November 2,018
Spectra Energy Capital, LLC | 8.00% senior unsecured notes due October 2019
Debt Instrument [Line Items]
Unsecured Debt		$ 500	500
Debt Instrument, Interest Rate, Stated Percentage		8.00%
Debt Instrument, Maturity Date, Description		October 2,019
Spectra Energy Capital, LLC | 5.65% senior unsecured notes due March 2020
Debt Instrument [Line Items]
Unsecured Debt		$ 300	300
Debt Instrument, Interest Rate, Stated Percentage		5.65%
Debt Instrument, Maturity Date, Description		March 2,020
Spectra Energy Capital, LLC | 3.30% senior unsecured notes due March 2023
Debt Instrument [Line Items]
Unsecured Debt		$ 650	650
Debt Instrument, Interest Rate, Stated Percentage		3.30%
Debt Instrument, Maturity Date, Description		March 2,023
Spectra Energy Capital, LLC | 6.75% senior unsecured notes due February 2032
Debt Instrument [Line Items]
Unsecured Debt		$ 240	240
Debt Instrument, Interest Rate, Stated Percentage		6.75%
Debt Instrument, Maturity Date, Description		February 2,032
Spectra Energy Capital, LLC | 7.50% senior unsecured notes due September 2038
Debt Instrument [Line Items]
Unsecured Debt		$ 250	250
Debt Instrument, Interest Rate, Stated Percentage		7.50%
Debt Instrument, Maturity Date, Description		September 2,038
Spectra Energy Partners, LP
Debt Instrument [Line Items]
Long-term debt principal (including current maturities)		$ 6,672	6,152
Spectra Energy Partners, LP | SEP 2.95% senior unsecured notes due June 2016
Debt Instrument [Line Items]
Unsecured Debt		$ 0	250
Debt Instrument, Interest Rate, Stated Percentage		2.95%
Debt Instrument, Maturity Date, Description		June 2,016
Spectra Energy Partners, LP | SEP 2.95% senior unsecured notes due September 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 500	500
Debt Instrument, Interest Rate, Stated Percentage		2.95%
Debt Instrument, Maturity Date, Description		September 2,018
Spectra Energy Partners, LP | SEP variable-rate senior unsecured term loan due November 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 400	400
Debt Instrument, Maturity Date, Description		November 2,018
Spectra Energy Partners, LP | SEP 4.60% senior unsecured notes due June 2021
Debt Instrument [Line Items]
Unsecured Debt		$ 250	250
Debt Instrument, Interest Rate, Stated Percentage		4.60%
Debt Instrument, Maturity Date, Description		June 2,021
Spectra Energy Partners, LP | SEP 4.75% senior unsecured notes due March 2024
Debt Instrument [Line Items]
Unsecured Debt		$ 1,000	1,000
Debt Instrument, Interest Rate, Stated Percentage		4.75%
Debt Instrument, Maturity Date, Description		March 2,024
Spectra Energy Partners, LP | SEP 3.50% senior unsecured notes due March 2025
Debt Instrument [Line Items]
Unsecured Debt		$ 500	500
Debt Instrument, Interest Rate, Stated Percentage		3.50%
Debt Instrument, Maturity Date, Description		March 2,025
Spectra Energy Partners, LP | SEP 3.375% senior unsecured notes due October 2026
Debt Instrument [Line Items]
Unsecured Debt		$ 600	0
Debt Instrument, Interest Rate, Stated Percentage		3.375%
Debt Instrument, Maturity Date, Description		October 2,026
Spectra Energy Partners, LP | SEP 5.95% senior unsecured notes due September 2043
Debt Instrument [Line Items]
Unsecured Debt		$ 400	400
Debt Instrument, Interest Rate, Stated Percentage		5.95%
Debt Instrument, Maturity Date, Description		September 2,043
Spectra Energy Partners, LP | SEP 4.50% senior unsecured notes due March 2045
Debt Instrument [Line Items]
Unsecured Debt		$ 700	500
Debt Instrument, Interest Rate, Stated Percentage		4.50%
Debt Instrument, Maturity Date, Description		March 2,045
Texas Eastern | Texas Eastern 6.00% senior unsecured notes due September 2017
Debt Instrument [Line Items]
Unsecured Debt		$ 400	400
Debt Instrument, Interest Rate, Stated Percentage		6.00%
Debt Instrument, Maturity Date, Description		September 2,017
Texas Eastern | Texas Eastern 4.125% senior unsecured notes due December 2020
Debt Instrument [Line Items]
Unsecured Debt		$ 300	300
Debt Instrument, Interest Rate, Stated Percentage		4.125%
Debt Instrument, Maturity Date, Description		December 2,020
Texas Eastern | Texas Eastern 2.80% senior unsecured notes due October 2022
Debt Instrument [Line Items]
Unsecured Debt		$ 500	500
Debt Instrument, Interest Rate, Stated Percentage		2.80%
Debt Instrument, Maturity Date, Description		October 2,022
Texas Eastern | Texas Eastern 7.00% senior unsecured notes due July 2032
Debt Instrument [Line Items]
Unsecured Debt		$ 450	450
Debt Instrument, Interest Rate, Stated Percentage		7.00%
Debt Instrument, Maturity Date, Description		July 2,032
Algonquin | Algonquin 3.51% senior notes due July 2024
Debt Instrument [Line Items]
Unsecured Debt		$ 350	350
Debt Instrument, Interest Rate, Stated Percentage		3.51%
Debt Instrument, Maturity Date, Description		July 2,024
East Tennessee Natural Gas, LLC | East Tennessee Natural Gas, LLC 3.10% senior notes due December 2024
Debt Instrument [Line Items]
Unsecured Debt		$ 200	200
Debt Instrument, Interest Rate, Stated Percentage		3.10%
Debt Instrument, Maturity Date, Description		December 2,024
Express-Platte | Express-Platte 6.09% senior secured notes due January 2020
Debt Instrument [Line Items]
Secured Debt		$ 110	110
Debt Instrument, Interest Rate, Stated Percentage		6.09%
Debt Instrument, Maturity Date, Description		January 2,020
Express-Platte | Express-Platte 7.39% subordinated secured notes due 2017 to 2019
Debt Instrument [Line Items]
Secured Debt		$ 12	42
Debt Instrument, Interest Rate, Stated Percentage		7.39%
Debt Instrument, Maturity Date, Description		2017 to 2019
Westcoast Energy Inc.
Debt Instrument [Line Items]
Long-term debt principal (including current maturities)		$ 2,097	2,256
Westcoast Energy Inc. | 3.28% medium-term notes due January 2016
Debt Instrument [Line Items]
Unsecured Debt		$ 0	181
Debt Instrument, Interest Rate, Stated Percentage		3.28%
Debt Instrument, Maturity Date, Description		January 2,016
Westcoast Energy Inc. | 8.50% debentures due September 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 112	108
Debt Instrument, Interest Rate, Stated Percentage		8.50%
Debt Instrument, Maturity Date, Description		September 2,018
Westcoast Energy Inc. | 5.60% medium-term notes due January 2019
Debt Instrument [Line Items]
Unsecured Debt		$ 223	217
Debt Instrument, Interest Rate, Stated Percentage		5.60%
Debt Instrument, Maturity Date, Description		January 2,019
Westcoast Energy Inc. | 9.90% debentures due January 2020
Debt Instrument [Line Items]
Unsecured Debt		$ 74	72
Debt Instrument, Interest Rate, Stated Percentage		9.90%
Debt Instrument, Maturity Date, Description		January 2,020
Westcoast Energy Inc. | 4.57% medium-term notes due July 2020
Debt Instrument [Line Items]
Unsecured Debt		$ 186	181
Debt Instrument, Interest Rate, Stated Percentage		4.57%
Debt Instrument, Maturity Date, Description		July 2,020
Westcoast Energy Inc. | 3.883% medium-term notes due October 2021
Debt Instrument [Line Items]
Unsecured Debt		$ 112	108
Debt Instrument, Interest Rate, Stated Percentage		3.883%
Debt Instrument, Maturity Date, Description		October 2,021
Westcoast Energy Inc. | 3.12% medium-term notes due December 2022
Debt Instrument [Line Items]
Unsecured Debt		$ 186	181
Debt Instrument, Interest Rate, Stated Percentage		3.12%
Debt Instrument, Maturity Date, Description		December 2,022
Westcoast Energy Inc. | 3.43% medium-term notes due September 2024
Debt Instrument [Line Items]
Unsecured Debt		$ 260	253
Debt Instrument, Interest Rate, Stated Percentage		3.43%
Debt Instrument, Maturity Date, Description		September 2,024
Westcoast Energy Inc. | 8.85% debentures due July 2025
Debt Instrument [Line Items]
Unsecured Debt		$ 112	108
Debt Instrument, Interest Rate, Stated Percentage		8.85%
Debt Instrument, Maturity Date, Description		July 2,025
Westcoast Energy Inc. | 8.80% medium-term notes due November 2025
Debt Instrument [Line Items]
Unsecured Debt		$ 18	18
Debt Instrument, Interest Rate, Stated Percentage		8.80%
Debt Instrument, Maturity Date, Description		November 2,025
Westcoast Energy Inc. | 3.77% medium-term notes due December 2025
Debt Instrument [Line Items]
Unsecured Debt		$ 223	217
Debt Instrument, Interest Rate, Stated Percentage		3.77%
Debt Instrument, Maturity Date, Description		December 2,025
Westcoast Energy Inc. | 7.30% debentures due December 2026
Debt Instrument [Line Items]
Unsecured Debt		$ 93	90
Debt Instrument, Interest Rate, Stated Percentage		7.30%
Debt Instrument, Maturity Date, Description		December 2,026
Westcoast Energy Inc. | 6.75% medium-term notes due December 2027
Debt Instrument [Line Items]
Unsecured Debt		$ 112	108
Debt Instrument, Interest Rate, Stated Percentage		6.75%
Debt Instrument, Maturity Date, Description		December 2,027
Westcoast Energy Inc. | 7.15% medium-term notes due March 2031
Debt Instrument [Line Items]
Unsecured Debt		$ 149	145
Debt Instrument, Interest Rate, Stated Percentage		7.15%
Debt Instrument, Maturity Date, Description		March 2,031
Westcoast Energy Inc. | 4.791% medium-term notes due October 2041
Debt Instrument [Line Items]
Unsecured Debt		$ 149	145
Debt Instrument, Interest Rate, Stated Percentage		4.791%
Debt Instrument, Maturity Date, Description		October 2,041
Westcoast Energy Inc. | Other
Debt Instrument [Line Items]
Unsecured Debt		$ 2	2
Maritimes & Northeast Pipeline Limited Partnership | M&N Canada 6.90% senior secured notes due 2017 to 2019
Debt Instrument [Line Items]
Secured Debt		$ 58	75
Debt Instrument, Interest Rate, Stated Percentage		6.90%
Debt Instrument, Maturity Date, Description		2017 to 2019
Maritimes & Northeast Pipeline Limited Partnership | M&N Canada 4.34% senior secured notes due 2017 to 2019
Debt Instrument [Line Items]
Secured Debt		$ 28	47
Debt Instrument, Interest Rate, Stated Percentage		4.34%
Debt Instrument, Maturity Date, Description		2017 to 2019
Union Gas Limited
Debt Instrument [Line Items]
Long-term debt principal (including current maturities)		$ 2,559	2,269
Union Gas Limited | 4.64% medium-term notes due June 2016
Debt Instrument [Line Items]
Unsecured Debt		$ 0	145
Debt Instrument, Interest Rate, Stated Percentage		4.64%
Debt Instrument, Maturity Date, Description		June 2,016
Union Gas Limited | 9.70% debentures due November 2017
Debt Instrument [Line Items]
Unsecured Debt		$ 93	90
Debt Instrument, Interest Rate, Stated Percentage		9.70%
Debt Instrument, Maturity Date, Description		November 2,017
Union Gas Limited | 5.35% medium-term notes due April 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 149	145
Debt Instrument, Interest Rate, Stated Percentage		5.35%
Debt Instrument, Maturity Date, Description		April 2,018
Union Gas Limited | 8.75% debentures due August 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 93	90
Debt Instrument, Interest Rate, Stated Percentage		8.75%
Debt Instrument, Maturity Date, Description		August 2,018
Union Gas Limited | 8.65% senior debentures due October 2018
Debt Instrument [Line Items]
Unsecured Debt		$ 56	54
Debt Instrument, Interest Rate, Stated Percentage		8.65%
Debt Instrument, Maturity Date, Description		October 2,018
Union Gas Limited | 2.76% medium-term notes due June 2021
Debt Instrument [Line Items]
Unsecured Debt		$ 149	145
Debt Instrument, Interest Rate, Stated Percentage		2.76%
Debt Instrument, Maturity Date, Description		June 2,021
Union Gas Limited | 4.85% medium-term notes due April 2022
Debt Instrument [Line Items]
Unsecured Debt		$ 93	90
Debt Instrument, Interest Rate, Stated Percentage		4.85%
Debt Instrument, Maturity Date, Description		April 2,022
Union Gas Limited | 3.79% medium-term notes due July 2023
Debt Instrument [Line Items]
Unsecured Debt		$ 186	181
Debt Instrument, Interest Rate, Stated Percentage		3.79%
Debt Instrument, Maturity Date, Description		July 2,023
Union Gas Limited | 3.19% medium-term notes due September 2025
Debt Instrument [Line Items]
Unsecured Debt		$ 149	145
Debt Instrument, Interest Rate, Stated Percentage		3.19%
Debt Instrument, Maturity Date, Description		September 2,025
Union Gas Limited | 8.65% debentures due November 2025
Debt Instrument [Line Items]
Unsecured Debt		$ 93	90
Debt Instrument, Interest Rate, Stated Percentage		8.65%
Debt Instrument, Maturity Date, Description		November 2,025
Union Gas Limited | 2.81% medium-term note debentures due June 2026
Debt Instrument [Line Items]
Unsecured Debt		$ 186	0
Debt Instrument, Interest Rate, Stated Percentage		2.81%
Debt Instrument, Maturity Date, Description		June 2,026
Union Gas Limited | 5.46% medium-term notes due September 2036
Debt Instrument [Line Items]
Unsecured Debt		$ 123	119
Debt Instrument, Interest Rate, Stated Percentage		5.46%
Debt Instrument, Maturity Date, Description		September 2,036
Union Gas Limited | 6.05% medium-term notes due September 2038
Debt Instrument [Line Items]
Unsecured Debt		$ 223	216
Debt Instrument, Interest Rate, Stated Percentage		6.05%
Debt Instrument, Maturity Date, Description		September 2,038
Union Gas Limited | 5.20% medium-term notes due July 2040
Debt Instrument [Line Items]
Unsecured Debt		$ 186	181
Debt Instrument, Interest Rate, Stated Percentage		5.20%
Debt Instrument, Maturity Date, Description		July 2,040
Union Gas Limited | 4.88% medium-term notes due June 2041
Debt Instrument [Line Items]
Unsecured Debt		$ 223	217
Debt Instrument, Interest Rate, Stated Percentage		4.88%
Debt Instrument, Maturity Date, Description		June 2,041
Union Gas Limited | 4.20% medium-term notes due June 2044
Debt Instrument [Line Items]
Unsecured Debt		$ 371	361
Debt Instrument, Interest Rate, Stated Percentage		4.20%
Debt Instrument, Maturity Date, Description		June 2,044
Union Gas Limited | 3.80% medium-term note debentures due June 2046
Debt Instrument [Line Items]
Unsecured Debt		$ 186	$ 0
Debt Instrument, Interest Rate, Stated Percentage		3.80%
Debt Instrument, Maturity Date, Description		June 2,046
[1]	The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015.
[2]	Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015.
[3]	As of December 31, 2016 and 2015, respectively, $4,904 million and $4,681 million of debt was denominated in Canadian dollars.

Debt and Credit Facilities S106

Debt and Credit Facilities Summary of Debt and Related Terms - Table Footnotes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Commercial Paper Weighted Average Life Period	14	12
Short-term Debt, Weighted Average Interest Rate	1.08%	0.90%
Canadian Dollars
Debt Instrument [Line Items]
Long-term debt, including current maturities	$ 4,904	$ 4,681

Debt and Credit Facilities S107

Debt and Credit Facilities Summary of Debt and Related Terms - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Secured Debt	$ 208
Long-term Debt, Percentage Bearing Variable Interest, Amount	$ 2,153	$ 1,812
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.35%	1.15%

Debt and Credit Facilities Annu

Debt and Credit Facilities Annual Maturities (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
2,017		$ 548
2,018		2,290
2,019		751
2,020		970
2,021		510
Thereafter		9,163
Total long-term debt, including current maturities	[1]	14,232
Commercial Paper	[2],[3]	1,453	$ 1,112
Capital Leases		$ 14	$ 19
[1]	Excludes commercial paper of $1,453 million. Includes capital leases of $14 million.
[2]	The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015.
[3]	Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015.

Debt and Credit Facilities Avai

Debt and Credit Facilities Available Credit Facilities and Restrictive Debt Covenants (Detail) $ in Millions		12 Months Ended
		Dec. 31, 2016USD ($)		Dec. 31, 2016CAD	Dec. 31, 2015USD ($)
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity		$ 6,319
Commercial Paper	[1],[2]	1,453			$ 1,112
Available Credit Facilities Capacity		$ 4,866
Spectra Energy Capital, LLC | Multi Year Syndicated
Line of Credit Facility [Line Items]
Expiration Date	[3]	2,021
Total Credit Facilities Capacity	[3]	$ 1,000
Commercial Paper	[3]	631
Available Credit Facilities Capacity	[3]	$ 369
Spectra Energy Capital, LLC | 364-day syndicated
Line of Credit Facility [Line Items]
Expiration Date	[3]	2,017
Total Credit Facilities Capacity	[3]	$ 2,000
Commercial Paper	[3]	0
Available Credit Facilities Capacity	[3]	$ 2,000
Spectra Energy Partners, LP | Multi Year Syndicated
Line of Credit Facility [Line Items]
Expiration Date	[4]	2,021
Total Credit Facilities Capacity	[4]	$ 2,500
Commercial Paper	[4]	574
Available Credit Facilities Capacity	[4]	$ 1,926
Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Expiration Date		2,021
Westcoast Energy Inc. | Multi Year Syndicated
Line of Credit Facility [Line Items]
Expiration Date	[5]	2,021
Total Credit Facilities Capacity		$ 298	[5]	CAD 400,000,000
Commercial Paper	[5]	0
Available Credit Facilities Capacity	[5]	$ 298
Union Gas Limited | Multi Year Syndicated
Line of Credit Facility [Line Items]
Expiration Date	[6]	2,021
Total Credit Facilities Capacity		$ 521	[6]	CAD 700,000,000
Commercial Paper	[6]	248
Available Credit Facilities Capacity	[6]	$ 273
[1]	The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015.
[2]	Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015.
[3]	Revolving credit facilities contain a covenant requiring the Spectra Energy consolidated debt-to-total capitalization ratio, as defined in the agreements, to not exceed 65%. Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 56.3% at December 31, 2016.
[4]	Revolving credit facility contains a covenant that requires SEP to maintain a ratio of total Consolidated Indebtedness-to-Consolidated EBITDA, as defined in the agreement, of 5.0 to 1 or less. As of December 31, 2016, this ratio was 3.8 to 1.
[5]	U.S. dollar equivalent at December 31, 2016. The revolving credit facility is 400 million Canadian dollars and contains a covenant that requires the Westcoast non-consolidated debt-to-total capitalization ratio to not exceed 75%. The ratio was 33.2% at December 31, 2016.
[6]	U.S. dollar equivalent at December 31, 2016. The revolving credit facility is 700 million Canadian dollars and contains a covenant that requires the Union Gas debt-to-total capitalization ratio to not exceed 75% and a provision which requires Union Gas to repay all borrowings under the facility for a period of two days during the second quarter of each year. The ratio was 69.0% at December 31, 2016.

Debt and Credit Facilities A110

Debt and Credit Facilities Available Credit Facilities and Restrictive Debt Covenants - Table Footnotes (Detail) $ in Millions	Dec. 31, 2016USD ($)		Dec. 31, 2016CAD
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 6,319
Covenant Requirement | Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Debt to Total Capitalization	56.30%		56.30%
Covenant Requirement | Spectra Energy Capital, LLC | Maximum
Line of Credit Facility [Line Items]
Debt to Total Capitalization	65.00%		65.00%
Covenant Requirement | Spectra Energy Partners, LP
Line of Credit Facility [Line Items]
Debt To Adjusted EBITDA Ratio Maximum	5		5
Debt To Adjusted EBITDA Ratio	3.8		3.8
Covenant Requirement | Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Debt to Total Capitalization	33.20%		33.20%
Covenant Requirement | Westcoast Energy Inc. | Maximum
Line of Credit Facility [Line Items]
Debt to Total Capitalization	75.00%		75.00%
Covenant Requirement | Union Gas Limited
Line of Credit Facility [Line Items]
Debt to Total Capitalization	69.00%		69.00%
Covenant Requirement | Union Gas Limited | Maximum
Line of Credit Facility [Line Items]
Debt to Total Capitalization	75.00%		75.00%
Multi Year Syndicated | Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 1,000	[1]
Multi Year Syndicated | Spectra Energy Partners, LP
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	2,500	[2]
Multi Year Syndicated | Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	298	[3]	CAD 400,000,000
Multi Year Syndicated | Union Gas Limited
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 521	[4]	CAD 700,000,000
[1]	Revolving credit facilities contain a covenant requiring the Spectra Energy consolidated debt-to-total capitalization ratio, as defined in the agreements, to not exceed 65%. Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 56.3% at December 31, 2016.
[2]	Revolving credit facility contains a covenant that requires SEP to maintain a ratio of total Consolidated Indebtedness-to-Consolidated EBITDA, as defined in the agreement, of 5.0 to 1 or less. As of December 31, 2016, this ratio was 3.8 to 1.
[3]	U.S. dollar equivalent at December 31, 2016. The revolving credit facility is 400 million Canadian dollars and contains a covenant that requires the Westcoast non-consolidated debt-to-total capitalization ratio to not exceed 75%. The ratio was 33.2% at December 31, 2016.
[4]	U.S. dollar equivalent at December 31, 2016. The revolving credit facility is 700 million Canadian dollars and contains a covenant that requires the Union Gas debt-to-total capitalization ratio to not exceed 75% and a provision which requires Union Gas to repay all borrowings under the facility for a period of two days during the second quarter of each year. The ratio was 69.0% at December 31, 2016.

Available Credit Facilities and

Available Credit Facilities and Restrictive Debt Covenants - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016USD ($)		Dec. 31, 2016CAD
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 6,319,000,000
Line of Credit Facility, Covenant Compliance	Our credit agreements contain various covenants, including the maintenance of certain financial ratios. Failure to meet those covenants beyond applicable grace periods could result in accelerated due dates and/or termination of the agreements. As of December 31, 2016, we were in compliance with those covenants.
Revolving Borrowings
Line of Credit Facility [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding	$ 0
Letters of Credit
Line of Credit Facility [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding	0
Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Amount of Restricted Net Assets for Consolidated and Unconsolidated Subsidiaries	8,400,000,000
Spectra Energy Capital, LLC | 364-day syndicated
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 2,000,000,000	[1]
Expiration Date	2,017	[1]
Spectra Energy Capital, LLC | Multi Year Syndicated
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 1,000,000,000	[1]
Expiration Date	2,021	[1]
Union Gas Limited | Multi Year Syndicated
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 521,000,000	[2]	CAD 700,000,000
Expiration Date	2,021	[2]
Spectra Energy Partners, LP | Multi Year Syndicated
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 2,500,000,000	[3]
Expiration Date	2,021	[3]
Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Expiration Date	2,021
Westcoast Energy Inc. | Multi Year Syndicated
Line of Credit Facility [Line Items]
Total Credit Facilities Capacity	$ 298,000,000	[4]	CAD 400,000,000
Expiration Date	2,021	[4]
Covenant Requirement | Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Debt to Total Capitalization	56.30%		56.30%
Covenant Requirement | Union Gas Limited
Line of Credit Facility [Line Items]
Debt to Total Capitalization	69.00%		69.00%
Covenant Requirement | Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Debt to Total Capitalization	33.20%		33.20%
Maximum | Covenant Requirement | Spectra Energy Capital, LLC
Line of Credit Facility [Line Items]
Debt to Total Capitalization	65.00%		65.00%
Maximum | Covenant Requirement | Union Gas Limited
Line of Credit Facility [Line Items]
Debt to Total Capitalization	75.00%		75.00%
Maximum | Covenant Requirement | Westcoast Energy Inc.
Line of Credit Facility [Line Items]
Debt to Total Capitalization	75.00%		75.00%
[1]	Revolving credit facilities contain a covenant requiring the Spectra Energy consolidated debt-to-total capitalization ratio, as defined in the agreements, to not exceed 65%. Per the terms of the agreements, collateralized debt is excluded from the calculation of the ratio. This ratio was 56.3% at December 31, 2016.
[2]	U.S. dollar equivalent at December 31, 2016. The revolving credit facility is 700 million Canadian dollars and contains a covenant that requires the Union Gas debt-to-total capitalization ratio to not exceed 75% and a provision which requires Union Gas to repay all borrowings under the facility for a period of two days during the second quarter of each year. The ratio was 69.0% at December 31, 2016.
[3]	Revolving credit facility contains a covenant that requires SEP to maintain a ratio of total Consolidated Indebtedness-to-Consolidated EBITDA, as defined in the agreement, of 5.0 to 1 or less. As of December 31, 2016, this ratio was 3.8 to 1.
[4]	U.S. dollar equivalent at December 31, 2016. The revolving credit facility is 400 million Canadian dollars and contains a covenant that requires the Westcoast non-consolidated debt-to-total capitalization ratio to not exceed 75%. The ratio was 33.2% at December 31, 2016.

Preferred Stock of Subsidiar112

Preferred Stock of Subsidiaries (Details) shares in Millions, CAD in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)shares	Dec. 31, 2016CADshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2015CADshares	Dec. 31, 2014USD ($)
Preferred Shares of Subsidiaries [Line Items]
Proceeds from the issuance of Westcoast Energy Inc. preferred stock | $	$ 229		$ 84		$ 0
Westcoast Energy Inc. and Union Gas Limited
Preferred Shares of Subsidiaries [Line Items]
Percentage Of Redeemable Preferred Stock	49.70%	49.70%
Cumulative Five Year Minimum Rate Reset Redeemable First Preferred Shares, Series 12 [Member] | Westcoast Energy Inc.
Preferred Shares of Subsidiaries [Line Items]
Issuance of First Preferred Shares	12	12
Proceeds from the issuance of Westcoast Energy Inc. preferred stock	$ 229	CAD 300
Cumulative Five-Year Minimum Rate Reset Redeemable First Preferred Shares, Series 10 [Member] | Westcoast Energy Inc.
Preferred Shares of Subsidiaries [Line Items]
Issuance of First Preferred Shares			4.6	4.6
Proceeds from the issuance of Westcoast Energy Inc. preferred stock			$ 84	CAD 115

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis with Fair Value Hierarchy Levels (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	$ 250	$ 246
Corporate Debt Securities | Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	191	137
Corporate Debt Securities | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		20
Corporate Debt Securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	8	11
Commodity Contract | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		36
Commodity Contract | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		5
Interest Rate Swap | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	1
Interest Rate Swap | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	23	37
Canadian equity securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	27
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	27	0
Level 1 | Corporate Debt Securities | Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	0
Level 1 | Corporate Debt Securities | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		0
Level 1 | Corporate Debt Securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	0
Level 1 | Commodity Contract | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		0
Level 1 | Commodity Contract | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		0
Level 1 | Interest Rate Swap | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0
Level 1 | Interest Rate Swap | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	0
Level 1 | Canadian equity securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	27
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	223	205
Level 2 | Corporate Debt Securities | Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	191	137
Level 2 | Corporate Debt Securities | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		20
Level 2 | Corporate Debt Securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	8	11
Level 2 | Commodity Contract | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		0
Level 2 | Commodity Contract | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		0
Level 2 | Interest Rate Swap | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	1
Level 2 | Interest Rate Swap | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	23	37
Level 2 | Canadian equity securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0
Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	41
Level 3 | Corporate Debt Securities | Cash and Cash Equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	0
Level 3 | Corporate Debt Securities | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		0
Level 3 | Corporate Debt Securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	0
Level 3 | Commodity Contract | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		36
Level 3 | Commodity Contract | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets		5
Level 3 | Interest Rate Swap | Current Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0
Level 3 | Interest Rate Swap | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	0	$ 0
Level 3 | Canadian equity securities | Investments and Other Assets—Other
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value Assets	$ 0

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 Assets and Liabilities that are Measured at Fair Value on Recurring Basis using Significant Unobservable Inputs (Detail) - Derivative Financial Instruments, Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value, beginning of period	$ 41	$ 78
Total gains (losses):
Included in earnings	(7)	43
Included in other comprehensive income	1	(10)
Purchases	(1)	(3)
Settlements	(34)	(67)
Fair value, end of period	0	41
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Assets	$ 0	$ (19)

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Instruments Recorded and Carried at Book Value (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Book Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, noncurrent	[1]	$ 71	$ 71
Long-term debt, including current maturities	[2]	14,218	13,567
Approximate Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, noncurrent	[1]	71	71
Long-term debt, including current maturities	[2]	$ 15,168	$ 13,891
[1]	Included within Investments in and Loans to Unconsolidated Affiliates.
[2]	Excludes commercial paper, capital leases, unamortized items and fair value hedge carrying value adjustments.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring, Period Increase (Decrease)	$ 0
Liabilities, Fair Value Disclosure, Nonrecurring, Period Increase (Decrease)	0
Goodwill, Impairment Loss	$ 0	$ 333	$ 0
Western Canada Transmission & Processing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss		333
Western Canada Transmission & Processing | BC Pipeline and BC Field Services
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss		270
Western Canada Transmission & Processing | Empress
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss		$ 63

Risk Management and Hedging 117

Risk Management and Hedging Activities - Derivative Portfolio Carrying Value (Detail) gal in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)gal
Derivative Portfolio Carrying Value [Line Items]
Maturities in 2017	$ 1
Maturities in 2018	8
Maturities in 2019	0
Maturities in 2020 and Thereafter	15
Total Carrying Value	$ 24
Commodity Contract
Derivative Portfolio Carrying Value [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | gal	0
Designated as Hedging
Derivative Portfolio Carrying Value [Line Items]
Maturities in 2017	$ 1
Maturities in 2018	8
Maturities in 2019	0
Maturities in 2020 and Thereafter	15
Total Carrying Value	24
Interest Rate Swap | Designated as Hedging
Derivative Portfolio Carrying Value [Line Items]
Maturities in 2017	1
Maturities in 2018	8
Maturities in 2019	0
Maturities in 2020 and Thereafter	15
Total Carrying Value	$ 24

Risk Management and Hedging 118

Risk Management and Hedging Activities - Derivative Assets And Liabilities Offsetting Information (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Interest Rate Swap
Derivative Assets And Liabilities with Netting or Rights of Offset Arrangements [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 24	$ 37
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	0	0
Net Amount, Assets	$ 24	37
Commodity Contract
Derivative Assets And Liabilities with Netting or Rights of Offset Arrangements [Line Items]
Derivative Asset, Fair Value, Gross Asset		104
Derivative Asset, Fair Value, Amount Offset Against Collateral		63
Net Amount, Assets		41
Derivative Liability, Fair Value, Gross Liability		63
Derivative Liability, Fair Value, Amount Offset Against Collateral		63
Net Amount, Liabilities		$ 0

Risk Management and Hedging 119

Risk Management and Hedging Activities - Commodity Derivative Impact on Consolidated Statements of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commodity Contract | Sales of Natural Gas Liquids
Commodity Derivative Impact on Consolidated Statements of Income [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 8	$ 40	$ 93

- Risk Management and Hedging A

- Risk Management and Hedging Activities - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pay Floating Receive Fixed Swaps
Derivative [Line Items]
Derivative, Notional Amount	$ 2,000,000,000
Interest Expense
Derivative [Line Items]
Gain (Loss) on Interest Rate Fair Value Hedge Ineffectiveness	$ 0	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Accrual for Environmental Loss Contingencies	$ 6	$ 8
Loss Contingency, Estimate of Possible Loss	0	0
Operating Leases, Rent Expense	$ 39	$ 47	$ 38

Commitments and Contingencie122

Commitments and Contingencies - Summary of Future Minimum Lease Payments Under Operating Leases (Detail) $ in Millions	Dec. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 39
2,018	38
2,019	38
2,020	34
2,021	31
Thereafter	151
Total future minimum lease payments	$ 331

Guarantees and Indemnificati123

Guarantees and Indemnifications - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Westcoast Energy Inc.
Guarantor Obligations [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
DCP Midstream, LLC
Guarantor Obligations [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Fluor Enterprises, Inc. | Duke/Fluor Daniel
Guarantor Obligations [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Duke Energy Indemnified Guarantees
Guarantor Obligations [Line Items]
Maximum potential amount of future payments required to make under performance guarantees	$ 406
Duke Energy Indemnified Guarantees Expiring In Twenty Twenty Eight
Guarantor Obligations [Line Items]
Maximum potential amount of future payments required to make under performance guarantees	$ 201
Guarantee Year of Expiration	2,028
Guarantee of DCP Midstream's loan | DCP Midstream, LLC
Guarantor Obligations [Line Items]
Maximum potential amount of future payments required to make under performance guarantees	$ 225
Guarantee Year of Expiration	2,019
Spectra Energy Partners, LP | SEP Guarantee to Investee Expiring in Twenty Thirty Two
Guarantor Obligations [Line Items]
Maximum potential amount of future payments required to make under performance guarantees	$ 50
Guarantee Year of Expiration	2,032
DCP Midstream, LLC
Guarantor Obligations [Line Items]
Term loan agreement to finance ongoing operations	$ 424

Issuances of Common Stock - Add

Issuances of Common Stock - Additional Information (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended		12 Months Ended
	Apr. 30, 2016	Nov. 30, 2013	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Proceeds from the issuances of Spectra Energy common stock			$ 879	$ 0	$ 0
SE Corp At-the-Market program
Class of Stock [Line Items]
Spectra Energy common stock issued, shares			12.9
Proceeds from the issuances of Spectra Energy common stock			$ 383
Overnight equity offering
Class of Stock [Line Items]
Spectra Energy common stock issued, shares	16.1
Proceeds from the issuances of Spectra Energy common stock	$ 479
Private Placement | Spectra Energy Partners, LP | Spectra Energy Corp | Limited Partner
Class of Stock [Line Items]
Spectra Energy purchase of SEP's common units	10.4
Maximum | Spectra Energy Partners, LP
Class of Stock [Line Items]
Potential Proceeds from the issuance of Common Stock		$ 1,000
Maximum | SE Corp At-the-Market program
Class of Stock [Line Items]
Potential Proceeds from the issuance of Common Stock			$ 500

Effects of Changes in Noncon125

Effects of Changes in Noncontrolling Interests Ownership Effects of Changes in Noncontrolling Interests Ownership (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Noncontrolling Interest [Line Items]
Net Income—Controlling Interests		$ 115	$ 195	$ 149	$ 234	$ (263)	$ 174	$ 18	$ 267	$ 693	$ 196	$ 1,082
Increase (decrease) in additional paid-in capital resulting from issuances/retirements of SEP units (a)										559	530	297
Total net income—controlling interests and changes in equity—controlling interests										724	91	1,131
Additional Paid-in Capital
Noncontrolling Interest [Line Items]
Increase (decrease) in additional paid-in capital resulting from issuances/retirements of SEP units (a)	[1]									$ 31	$ (105)	$ 49
[1]	See Note 2 for further discussion.

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of common stock awarded (in shares)	53,000,000
Tax benefit in income from continuing operations associated with recorded expense	$ 10	$ 7	$ 7
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	$ 11	$ 1	$ 3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	925,000	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 2
Restricted awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based awards granted percentage vested	100.00%
Stock-based awards vesting period	3 years
Performance awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based awards granted percentage vested	100.00%
Stock-based awards vesting period	3 years
Awards Granted (in shares)	594,000
Total fair value of shares vested	$ 26		$ 20
Future compensation cost related to stock awards expected to be recognized	$ 27
Performance awards | Total shareholder return
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested and outstanding performance awards granted containing EBITDA	1,350,249
Performance awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of shares vested		$ 1
Expected future compensation cost related to stock awards, weighted-average period of recognition	2 years
Phantom Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based awards granted percentage vested	100.00%
Stock-based awards vesting period	3 years
Awards Granted (in shares)	543,000
Total fair value of shares vested	$ 16	13	11
Future compensation cost related to stock awards expected to be recognized	$ 17
Phantom Stock Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected future compensation cost related to stock awards, weighted-average period of recognition	2 years
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based awards vesting period	3 years
Stock-based awards term	10 years
Future compensation cost related to stock awards expected to be recognized	$ 1
Expected future compensation cost related to stock awards, weighted-average period of recognition	2 years
Total intrinsic value of options exercised	$ 11	1	6
Cash received from options exercised	$ 22	$ 3	$ 11
Equity-classified awards | Performance awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted (in shares)	593,600	564,300	557,100
Fair value of equity classified awards granted	$ 31	$ 27	$ 26
Equity-classified awards | Phantom Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted (in shares)	240,610	39,200	101,500
Fair value of equity classified awards granted	$ 7	$ 1	$ 4
Liability-classified award | Performance awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted (in shares)	0	0	0
Liability-classified award | Phantom Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards Granted (in shares)	302,150	356,100	353,000
Fair value of equity classified awards granted	$ 9	$ 13	$ 13

Stock-Based Compensation - Comp

Stock-Based Compensation - Components of Pre-Tax Stock Based Compensation Expense in Continuing Operations (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre tax stock based compensation	$ 53	$ 29	$ 27
Phantom stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre tax stock based compensation	25	11	14
Performance awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre tax stock based compensation	27	18	13
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre tax stock based compensation	$ 1	$ 0	$ 0

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Awards Activity (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Performance Awards
Units
Outstanding at beginning of period (in shares) | shares	1,702
Granted (in shares) | shares	594
Vested (in shares) | shares	(687)
Forfeited (in shares) | shares	(259)
Outstanding at end of period (in shares) | shares	1,350
Awards expected to vest (in shares) | shares	1,302
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in usd per share) | $ / shares	$ 39
Granted (in usd per share) | $ / shares	53
Vested (in usd per share) | $ / shares	38
Forfeited (in usd per share) | $ / shares	37
Outstanding at end of period (in usd per share) | $ / shares	49
Awards expected to vest (in usd per share) | $ / shares	$ 49
Phantom Stock Awards
Units
Outstanding at beginning of period (in shares) | shares	1,212
Granted (in shares) | shares	543
Vested (in shares) | shares	(504)
Forfeited (in shares) | shares	(51)
Outstanding at end of period (in shares) | shares	1,200
Awards expected to vest (in shares) | shares	1,168
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in usd per share) | $ / shares	$ 28
Granted (in usd per share) | $ / shares	29
Vested (in usd per share) | $ / shares	32
Forfeited (in usd per share) | $ / shares	27
Outstanding at end of period (in usd per share) | $ / shares	39
Awards expected to vest (in usd per share) | $ / shares	$ 39

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Assumptions for Performance Awards (Detail) - Performance Awards	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate of return	0.90%	1.10%	0.70%
Expected life	3 years	3 years	3 years
Expected volatility—Spectra Energy	24.00%	18.00%	20.00%
Expected volatility, Minimum-peer group	19.00%	13.00%	14.00%
Expected volatility, Maximum-peer group	69.00%	27.00%	32.00%

Stock-Based Compensation - S130

Stock-Based Compensation - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options
Outstanding at beginning of period (in shares)	958,000
Granted (in shares)	925,000	0	0
Exercised (in shares)	(875,000)
Forfeited or expired (in shares)	(33,000)
Outstanding at end of period (in shares)	975,000	958,000
Exercisable at end of period (in shares)	86,000
Weighted- Average Exercise Price
Outstanding at beginning of period (in usd per share)	$ 26
Granted (in usd per share)	28
Exercised (in usd per share)	26
Forfeited or expired (in usd per share)	28
Outstanding at end of period (in usd per share)	28	$ 26
Exercisable at end of period (in usd per share)	$ 26
Weighted- Average Remaining Life
Outstanding at beginning of period	8 years 4 months 24 days	1 year 2 months 12 days
Outstanding at end of period	8 years 4 months 24 days	1 year 2 months 12 days
Exercisable at end of period	6 months
Aggregate Intrinsic Value
Outstanding at beginning of period	$ 0
Outstanding at end of period	13	$ 0
Exercisable at end of period	$ 1

Stock-Based Compensation - W131

Stock-Based Compensation - Weighted Average Assumptions for Options Awards (Details) - Stock options	12 Months Ended
	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate of return	1.40%
Expected life	6 years
Expected volatility	22.70%
Expected dividend yield	5.70%

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer		$ 1	$ 12
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year		$ 3
Average Remaining Service Period Of Active Employees		14 years
Defined Benefit Plan Periods Of Changes In Fair Value Of Plan Asset Used To Determine Market Related Value		5 years
Defined Benefit Plan, Benefit Obligation		$ 175	166	$ 172
Fair values of plan assets		79	88	92
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)		1
Canadian Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer		4	4
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year		4
Defined Benefit Plan, Benefit Obligation		108	107	133
Fair values of plan assets		0	0	0
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)		1
U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer		22	22	21
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year		$ 2
Average Remaining Service Period Of Active Employees		11 years
Defined Benefit Plan Periods Of Changes In Fair Value Of Plan Asset Used To Determine Market Related Value		5 years
Defined Benefit Plan, Benefit Obligation		$ 595	571	586
Defined Benefit Plan, Accumulated Benefit Obligation		569	549
Fair values of plan assets		554	532	551
Defined Benefit Plan, Future Amortization of Gain (Loss)		(8)
U.S. | Nonqualifed and Unfunded Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation		24	23
U.S. | Plans with accumulated benefit obligations in excess of plan assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation		24
Defined Benefit Plan, Accumulated Benefit Obligation		21
Fair values of plan assets		0
Canada
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer		17	22	36
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year		$ 24
Average Remaining Service Period Of Active Employees		13 years
Defined Benefit Plan Periods Of Changes In Fair Value Of Plan Asset Used To Determine Market Related Value		3 years
Defined Benefit Plan, Benefit Obligation		$ 1,110	1,034	1,202
Defined Benefit Plan, Accumulated Benefit Obligation		1,041	967
Fair values of plan assets		949	908	1,050
Defined Benefit Plan, Future Amortization of Gain (Loss)		(16)
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)		1
Canada | Nonqualifed and Unfunded Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Benefit Obligation		112	103
Canada | Plans with accumulated benefit obligations in excess of plan assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation		811
Defined Benefit Plan, Accumulated Benefit Obligation		748
Fair values of plan assets		$ 631
U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		6.00%
Defined Contribution Plan, Cost Recognized		$ 15	15	15
Canada
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount		$ 8	8	9
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		5.00%
Defined Contribution Plan, Cost Recognized		$ 12	13	$ 13
Money Market Funds | Investments and Other Assets—Other | Level 1
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Money Market Funds Fair Value Disclosure		$ 64	$ 18
Scenario, Forecast | Canada
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 8

Employee Benefit Plans - Change

Employee Benefit Plans - Change in Projected Benefit Obligation and Change in Fair Value of Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S.
Change in Projected Benefit Obligation
Projected benefit obligation, beginning balance	$ 571	$ 586
Service cost	19	19
Interest cost	25	24	$ 24
Actuarial loss (gain)	21	(18)
Participant contributions	0	0
Benefits paid	(41)	(40)
Defined Benefit Plan, Settlements, Benefit Obligation	0	0
Foreign currency translation effect	0	0
Projected benefit obligation, ending balance	595	571	586
Change in Fair Value of Plan Assets
Plan assets, beginning of period	532	551
Actual return on plan assets	41	(1)
Benefits paid	(41)	(40)
Employer contributions	22	22	21
Plan participants’ contributions	0	0
Expected non-investment expenses	0	0
Defined Benefit Plan, Settlements, Plan Assets	0	0
Foreign currency translation effect	0	0
Plan assets, end of period	554	532	551
Net amount recognized	(41)	(39)
Accumulated Benefit Obligation	569	549
U.S. | Current Liabilities—Other
Change in Fair Value of Plan Assets
Net amount recognized	(2)	(2)
U.S. | Deferred Credits and Other Liabilities—Regulatory and Other
Change in Fair Value of Plan Assets
Net amount recognized	(39)	(37)
U.S. | Investments and Other Assets—Other
Change in Fair Value of Plan Assets
Net amount recognized	0	0
Canada
Change in Projected Benefit Obligation
Projected benefit obligation, beginning balance	1,034	1,202
Service cost	28	28
Interest cost	43	43	52
Actuarial loss (gain)	30	(3)
Participant contributions	5	5
Benefits paid	(48)	(47)
Defined Benefit Plan, Settlements, Benefit Obligation	(13)	0
Foreign currency translation effect	31	(194)
Projected benefit obligation, ending balance	1,110	1,034	1,202
Change in Fair Value of Plan Assets
Plan assets, beginning of period	908	1,050
Actual return on plan assets	55	52
Benefits paid	(48)	(47)
Employer contributions	17	22	36
Plan participants’ contributions	5	5
Expected non-investment expenses	(3)	(3)
Defined Benefit Plan, Settlements, Plan Assets	(11)	0
Foreign currency translation effect	26	(171)
Plan assets, end of period	949	908	$ 1,050
Net amount recognized	(161)	(126)
Accumulated Benefit Obligation	1,041	967
Canada | Current Liabilities—Other
Change in Fair Value of Plan Assets
Net amount recognized	(6)	(5)
Canada | Deferred Credits and Other Liabilities—Regulatory and Other
Change in Fair Value of Plan Assets
Net amount recognized	(175)	(142)
Canada | Investments and Other Assets—Other
Change in Fair Value of Plan Assets
Net amount recognized	$ 20	$ 21

Employee Benefit Plans - Amount

Employee Benefit Plans - Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
U.S.
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 167	$ 156
Prior service cost	0	0
Total amount recognized in AOCI	167	156
Canada
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	348	330
Prior service cost	3	5
Total amount recognized in AOCI	$ 351	$ 335

Employee Benefit Plans - Compon

Employee Benefit Plans - Components of Net Periodic Pension Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S.
Net Periodic Pension Cost
Service cost benefit earned	$ 19	$ 19	$ 19
Interest cost on projected benefit obligation	25	24	24
Expected return on plan assets	(39)	(42)	(39)
Amortization of prior service cost	0	0	0
Amortization of loss	7	10	13
Curtailment effect	0	0	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	0	0
Net periodic other post-retirement benefit cost	12	11	17
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Current year actuarial loss	18	25	8
Amortization of actuarial loss	(7)	(10)	(13)
Amortization of prior service credit	0	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Curtailment Effect, before Tax	0	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Settlement Effect, before Tax	0	0	0
Total recognized in other comprehensive income	11	15	(5)
Total Recognized in Net Periodic Pension Cost and Other Comprehensive Income	23	26	12
Canada
Net Periodic Pension Cost
Service cost benefit earned	31	31	29
Interest cost on projected benefit obligation	43	43	52
Expected return on plan assets	(64)	(65)	(69)
Amortization of prior service cost	1	1	2
Amortization of loss	18	25	22
Curtailment effect	1	0	0
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	1	0	0
Net periodic other post-retirement benefit cost	31	35	36
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Current year actuarial loss	39	10	93
Amortization of actuarial loss	(18)	(25)	(22)
Amortization of prior service credit	(1)	(1)	(2)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Curtailment Effect, before Tax	(1)	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Settlement Effect, before Tax	(3)	0	0
Total recognized in other comprehensive income	16	(16)	69
Total Recognized in Net Periodic Pension Cost and Other Comprehensive Income	$ 47	$ 19	$ 105

Employee Benefit Plans - Assump

Employee Benefit Plans - Assumptions Used for Pension Benefits Accounting (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S.
Benefit Obligations
Discount rate	4.11%	4.58%	4.10%
Salary increase	4.00%	4.00%	4.00%
Net Periodic Benefit Cost
Discount rate	4.58%	4.10%	4.31%
Salary increase	4.00%	4.00%	4.61%
Expected long-term rate of return on plan assets	7.50%	8.00%	8.00%
Canada
Benefit Obligations
Discount rate	3.81%	4.03%	4.00%
Salary increase	3.00%	3.00%	3.25%
Net Periodic Benefit Cost
Discount rate	4.03%	4.00%	4.81%
Salary increase	3.00%	3.25%	3.25%
Expected long-term rate of return on plan assets	7.15%	7.40%	7.40%

Employee Benefit Plans - Qualif

Employee Benefit Plans - Qualified Pension Plan Assets (Detail) - Qualified pension plans	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S.
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	100.00%
Plan Asset Allocations	100.00%	100.00%
U.S. | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	23.00%
Plan Asset Allocations	22.00%	22.00%
U.S. | Canadian equity securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	0.00%
Plan Asset Allocations	0.00%	0.00%
U.S. | Other Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	10.00%
Plan Asset Allocations	9.00%	10.00%
U.S. | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	57.00%
Plan Asset Allocations	58.00%	57.00%
U.S. | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	10.00%
Plan Asset Allocations	11.00%	11.00%
Canada
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	100.00%
Plan Asset Allocations	100.00%	100.00%
Canada | U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	15.00%
Plan Asset Allocations	16.00%	18.00%
Canada | Canadian equity securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	23.00%
Plan Asset Allocations	28.00%	24.00%
Canada | Other Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	15.00%
Plan Asset Allocations	15.00%	13.00%
Canada | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	39.00%
Plan Asset Allocations	41.00%	45.00%
Canada | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Target Allocation	8.00%
Plan Asset Allocations	0.00%	0.00%

Employee Benefit Plans - Fair V

Employee Benefit Plans - Fair Values of Pension Plan Assets Recorded at Each Fair Value Hierarchy Level (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	$ 554	$ 532	$ 551
Canada
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	949	908	$ 1,050
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	554	532
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	3	2
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	171	171
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	317	304
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	63	55
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	491	477
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 1 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	3	2
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 1 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	171	171
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	317	304
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 1 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 2 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 2 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 2 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	63	55
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 3 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 3 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | U.S. | Fair Value, Measurements, Recurring | Level 3 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	63	55
Qualified pension plans | Canada | Fair Value, Measurements, Recurring
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	949	908
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	3	3
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	561	501
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	385	404
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	654	628
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 1 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	3	3
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 1 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	266	221
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 1 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	385	404
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 1 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	295	280
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 2 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 2 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	295	280
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 2 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 2 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 3 | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 3 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 3 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Qualified pension plans | Canada | Fair Value, Measurements, Recurring | Level 3 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	$ 0	$ 0

Employee Benefit Plans - Cha139

Employee Benefit Plans - Changes in Level 3 Assets That are Measured at Fair Value on Recurring Basis (Detail) - U.S. - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 55	$ 53
Gain (loss) included in other comprehensive income	8	2
Fair value, end of period	$ 63	$ 55

Employee Benefit Plans - Expect

Employee Benefit Plans - Expected Benefit Payments (Detail) - Qualified pension plans $ in Millions	Dec. 31, 2016USD ($)
U.S.
Defined Benefit Plan Disclosure [Line Items]
2,017	$ 104
2,018	46
2,019	48
2,020	47
2,021	49
Thereafter	231
Canada
Defined Benefit Plan Disclosure [Line Items]
2,017	49
2,018	51
2,019	53
2,020	55
2,021	57
Thereafter	$ 313

Employee Benefit Plans - Other

Employee Benefit Plans - Other Post Retirement Benefit Plans Change in Projected Benefit Obligation and Fair Value of Plan Assets (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Postretirement Benefit Plan
Change in Benefit Obligation
Projected benefit obligation, beginning balance		$ 166	$ 172
Service cost		1	1	$ 1
Interest cost		8	7	8
Plan participants' contributions		3	3
Actuarial loss (gain)		4	1
Prescription Drug Benefit, Effect of Subsidy on Net Periodic Postretirement Benefit Cost		1	2
Benefits paid		(18)	(20)
Plan change		10	0
Curtailment effect		0	0
Foreign currency translation effect		0	0
Projected benefit obligation, ending balance		175	166	172
Change in Fair Value of Plan Assets
Plan assets, beginning of period		88	92
Actual return on plan assets		5	1
Benefits paid		(18)	(20)
Employer contributions		1	12
Plan participants’ contributions		3	3
Plan assets, end of period		79	88	92
Net amount recognized	[1]	(96)	(78)
Canadian Postretirement Benefit Plan
Change in Benefit Obligation
Projected benefit obligation, beginning balance		107	133
Service cost		3	4	4
Interest cost		4	5	6
Plan participants' contributions		0	0
Actuarial loss (gain)		(5)	(11)
Prescription Drug Benefit, Effect of Subsidy on Net Periodic Postretirement Benefit Cost		0	0
Benefits paid		(4)	(4)
Plan change		0	0
Curtailment effect		(1)	0
Foreign currency translation effect		4	(20)
Projected benefit obligation, ending balance		108	107	133
Change in Fair Value of Plan Assets
Plan assets, beginning of period		0	0
Actual return on plan assets		0	0
Benefits paid		(4)	(4)
Employer contributions		4	4
Plan participants’ contributions		0	0
Plan assets, end of period		0	0	$ 0
Net amount recognized	[1]	$ (108)	$ (107)
[1]	Recognized primarily in Deferred Credits and Other Liabilities—Regulatory and Other in the Consolidated Balance Sheets.

Employee Benefit Plans - Oth142

Employee Benefit Plans - Other Post Retirement Benefit Plans Amounts Recognized in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
U.S. Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ 9	$ 0
Net actuarial loss	7	3
Total amount recognized in AOCI	16	3
Canadian Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	(2)	(3)
Net actuarial loss	(4)	1
Total amount recognized in AOCI	$ (6)	$ (2)

Employee Benefit Plans - Oth143

Employee Benefit Plans - Other Post Retirement Benefit Plans Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Postretirement Benefit Plan
Other Post-Retirement Benefit Plans-Components of Net Periodic Benefit Cost
Service cost benefit earned	$ 1	$ 1	$ 1
Interest cost on accumulated post-retirement benefit obligation	8	7	8
Expected return on plan assets	(5)	(6)	(5)
Amortization of prior service credit	1	0	0
Amortization of loss	0	0	1
Curtailment effect	0	0	0
Net periodic other post-retirement benefit cost	5	2	5
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Net prior service cost	10	0	0
Current year actuarial loss (gain)	4	7	(9)
Amortization of actuarial loss	0	0	(1)
Amortization of prior service credit	(1)	0	0
Total recognized in other comprehensive income	13	7	(10)
Total recognized in net periodic benefit cost and other comprehensive income	18	9	(5)
Canadian Postretirement Benefit Plan
Other Post-Retirement Benefit Plans-Components of Net Periodic Benefit Cost
Service cost benefit earned	3	4	4
Interest cost on accumulated post-retirement benefit obligation	4	5	6
Expected return on plan assets	0	0	0
Amortization of prior service credit	(1)	(1)	(1)
Amortization of loss	0	0	0
Curtailment effect	(1)	0	0
Net periodic other post-retirement benefit cost	5	8	9
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income
Net prior service cost	0	0	0
Current year actuarial loss (gain)	(5)	(11)	6
Amortization of actuarial loss	0	0	0
Amortization of prior service credit	1	1	1
Total recognized in other comprehensive income	(4)	(10)	7
Total recognized in net periodic benefit cost and other comprehensive income	$ 1	$ (2)	$ 16

Employee Benefit Plans - Oth144

Employee Benefit Plans - Other Post Retirement Benefits Plans Assumptions Used for Benefits Accounting (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
U.S. Postretirement Benefit Plan
Benefit Obligations
Discount rate	4.05%	4.53%	4.08%
Salary increase	4.00%	4.00%	4.00%
Net Periodic Benefit Cost
Discount rate	4.53%	4.08%	4.46%
Salary increase	4.00%	4.00%	4.61%
Expected return on plan assets	6.33%	6.83%	6.98%
Canadian Postretirement Benefit Plan
Benefit Obligations
Discount rate	3.81%	4.03%	4.00%
Salary increase	3.00%	3.00%	3.25%
Net Periodic Benefit Cost
Discount rate	4.03%	4.00%	4.83%
Salary increase	3.00%	3.25%	3.25%

Employee Benefit Plans - Assume

Employee Benefit Plans - Assumed Health Care Cost Trend Rates (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S. Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	7.00%	7.00%
Rate to which the cost trend is assumed to decline	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2,021	2,020
Canadian Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	5.00%	5.50%
Rate to which the cost trend is assumed to decline	5.00%	5.00%
Year that the rate reaches the ultimate trend rate	2,017	2,017

Employee Benefit Plans - Sensit

Employee Benefit Plans - Sensitivity to Changes in Assumed Health Care Cost Trend Rates (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
U.S. Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Effect of 1% point increase on total service and interest costs	$ 0
Effect of 1% point increase on post-retirement benefit obligations	8
Effect of 1% point decrease on total service and interest costs	0
Effect of 1% point decrease on post-retirement benefit obligations	(7)
Canadian Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Effect of 1% point increase on total service and interest costs	1
Effect of 1% point increase on post-retirement benefit obligations	5
Effect of 1% point decrease on total service and interest costs	0
Effect of 1% point decrease on post-retirement benefit obligations	$ (4)

Employee Benefit Plans - Oth147

Employee Benefit Plans - Other Post Retirement Plan Assets (Detail) - U.S. Postretirement Benefit Plan	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	100.00%	100.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	5.00%	3.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	39.00%	45.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	48.00%	46.00%
Other Assets
Defined Benefit Plan Disclosure [Line Items]
Plan asset allocations	8.00%	6.00%

Employee Benefit Plans - Fai148

Employee Benefit Plans - Fair Values of Other Post-Retirement Plan Assets Recorded at Each Hierarchy Level (Detail) - U.S. Postretirement Benefit Plan - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	$ 79	$ 88	$ 92
Fair Value, Measurements, Recurring | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	30	41
Fair Value, Measurements, Recurring | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	49	46
Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	4	3
Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Fair Value, Measurements, Recurring | Equity Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	16	24
Fair Value, Measurements, Recurring | Equity Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	15	15
Fair Value, Measurements, Recurring | Fixed Income Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	10	14
Fair Value, Measurements, Recurring | Fixed Income Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	28	26
Fair Value, Measurements, Recurring | Other Security Investments | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Fair Value, Measurements, Recurring | Other Security Investments | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	6	5
Level 1 | Fair Value, Measurements, Recurring | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	4	3
Level 1 | Fair Value, Measurements, Recurring | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	43	41
Level 1 | Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	4	3
Level 1 | Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 1 | Fair Value, Measurements, Recurring | Equity Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 1 | Fair Value, Measurements, Recurring | Equity Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	15	15
Level 1 | Fair Value, Measurements, Recurring | Fixed Income Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 1 | Fair Value, Measurements, Recurring | Fixed Income Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	28	26
Level 1 | Fair Value, Measurements, Recurring | Other Security Investments | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 1 | Fair Value, Measurements, Recurring | Other Security Investments | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	26	38
Level 2 | Fair Value, Measurements, Recurring | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Equity Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	16	24
Level 2 | Fair Value, Measurements, Recurring | Equity Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Fixed Income Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	10	14
Level 2 | Fair Value, Measurements, Recurring | Fixed Income Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Other Security Investments | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 2 | Fair Value, Measurements, Recurring | Other Security Investments | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	6	5
Level 3 | Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Cash and Cash Equivalents | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Equity Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Equity Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Fixed Income Securities | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Fixed Income Securities | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Other Security Investments | Veba Trust
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	0	0
Level 3 | Fair Value, Measurements, Recurring | Other Security Investments | Master Trust Fund
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	$ 6	$ 5

Employee Benefit Plans - Cha149

Employee Benefit Plans - Changes in Level 3 Assets That are Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Detail) - U.S. Postretirement Benefit Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	$ 5	$ 4
Unrealized gain included in other comprehensive income	1	1
Fair value, end of period	$ 6	$ 5

Employee Benefit Plans - Benefi

Employee Benefit Plans - Benefit Payments and Subsidies Expected to be Paid (or Received) (Detail) $ in Millions	Dec. 31, 2016USD ($)
U.S. Postretirement Benefit Plan
Benefit payments
2,017	$ 16
2,018	16
2,019	16
2,020	15
2,021	15
Thereafter	63
Medicare Part D subsidy receipts
2,017	(2)
2,018	(2)
2,019	(2)
2,020	(2)
2,021	(2)
Thereafter	(8)
Canadian Postretirement Benefit Plan
Benefit payments
2,017	4
2,018	4
2,019	4
2,020	4
2,021	5
Thereafter	$ 26

Condensed Consolidating Stateme

Condensed Consolidating Statement of Operations (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Total operating revenues	$ 1,298	$ 1,075	$ 1,159	$ 1,384	$ 1,316	$ 1,103	$ 1,192	$ 1,623	$ 4,916	$ 5,234	$ 5,903
Total operating expenses									3,331	3,805	3,978
Gain (Loss) on Sales of Other Assets and Other, net									(26)	4	(1)
Operating Income	373	321	371	494	97	389	406	541	1,559	1,433	1,924
Earnings (loss) from equity investments									97	(290)	361
Equity in earnings of consolidated subsidiaries									0	0	0
Other income and expenses, net									174	114	59
Interest expense									594	636	679
Earnings Before Income Taxes									1,236	621	1,665
Income tax expense (benefit)									216	161	382
Net Income	208	281	221	310	(188)	243	80	325	1,020	460	1,283
Net Income—Noncontrolling Interests									327	264	201
Net Income—Controlling Interests	$ 115	$ 195	$ 149	$ 234	$ (263)	$ 174	$ 18	$ 267	693	196	1,082
Eliminations
Condensed Financial Statements, Captions [Line Items]
Total operating revenues									(3)	(3)	(3)
Total operating expenses									(3)	(3)	(3)
Gain (Loss) on Sales of Other Assets and Other, net									0	0	0
Operating Income									0	0	0
Earnings (loss) from equity investments									0	0	0
Equity in earnings of consolidated subsidiaries									(1,837)	(734)	(2,705)
Other income and expenses, net									0	0	0
Interest expense									0	0	0
Earnings Before Income Taxes									(1,837)	(734)	(2,705)
Income tax expense (benefit)									0	0	0
Net Income									(1,837)	(734)	(2,705)
Net Income—Noncontrolling Interests									0	0	0
Net Income—Controlling Interests									(1,837)	(734)	(2,705)
Spectra Energy Corp
Condensed Financial Statements, Captions [Line Items]
Total operating revenues									0	0	0
Total operating expenses									7	6	6
Gain (Loss) on Sales of Other Assets and Other, net									0	0	0
Operating Income									(7)	(6)	(6)
Earnings (loss) from equity investments									0	0	0
Equity in earnings of consolidated subsidiaries									671	161	1,054
Other income and expenses, net									1	0	(2)
Interest expense									0	0	0
Earnings Before Income Taxes									665	155	1,046
Income tax expense (benefit)									(28)	(41)	(36)
Net Income									693	196	1,082
Net Income—Noncontrolling Interests									0	0	0
Net Income—Controlling Interests									693	196	1,082
Spectra Energy Capital, LLC
Condensed Financial Statements, Captions [Line Items]
Total operating revenues									0	0	0
Total operating expenses									4	(4)	1
Gain (Loss) on Sales of Other Assets and Other, net									0	0	0
Operating Income									(4)	4	(1)
Earnings (loss) from equity investments									0	0	0
Equity in earnings of consolidated subsidiaries									1,166	573	1,651
Other income and expenses, net									0	1	9
Interest expense									236	244	253
Earnings Before Income Taxes									926	334	1,406
Income tax expense (benefit)									255	173	352
Net Income									671	161	1,054
Net Income—Noncontrolling Interests									0	0	0
Net Income—Controlling Interests									671	161	1,054
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Total operating revenues									4,919	5,237	5,906
Total operating expenses									3,323	3,806	3,974
Gain (Loss) on Sales of Other Assets and Other, net									(26)	4	(1)
Operating Income									1,570	1,435	1,931
Earnings (loss) from equity investments									97	(290)	361
Equity in earnings of consolidated subsidiaries									0	0	0
Other income and expenses, net									173	113	52
Interest expense									358	392	426
Earnings Before Income Taxes									1,482	866	1,918
Income tax expense (benefit)									(11)	29	66
Net Income									1,493	837	1,852
Net Income—Noncontrolling Interests									327	264	201
Net Income—Controlling Interests									$ 1,166	$ 573	$ 1,651

Condensed Consolidating Stat152

Condensed Consolidating Statements of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net income	$ 208	$ 281	$ 221	$ 310	$ (188)	$ 243	$ 80	$ 325	$ 1,020	$ 460	$ 1,283
Other comprehensive income (loss)									126	(944)	(586)
Total Comprehensive Income (Loss), net of tax									1,146	(484)	697
Less: comprehensive income—noncontrolling interests									330	251	194
Comprehensive Income (Loss)—Controlling Interests									816	(735)	503
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income									(1,837)	(734)	(2,705)
Other comprehensive income (loss)									0	0	0
Total Comprehensive Income (Loss), net of tax									(1,837)	(734)	(2,705)
Less: comprehensive income—noncontrolling interests									0	0	0
Comprehensive Income (Loss)—Controlling Interests									(1,837)	(734)	(2,705)
Spectra Energy Corp
Condensed Financial Statements, Captions [Line Items]
Net income									693	196	1,082
Other comprehensive income (loss)									(15)	(14)	9
Total Comprehensive Income (Loss), net of tax									678	182	1,091
Less: comprehensive income—noncontrolling interests									0	0	0
Comprehensive Income (Loss)—Controlling Interests									678	182	1,091
Spectra Energy Capital, LLC
Condensed Financial Statements, Captions [Line Items]
Net income									671	161	1,054
Other comprehensive income (loss)									0	1	1
Total Comprehensive Income (Loss), net of tax									671	162	1,055
Less: comprehensive income—noncontrolling interests									0	0	0
Comprehensive Income (Loss)—Controlling Interests									671	162	1,055
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income									1,493	837	1,852
Other comprehensive income (loss)									141	(931)	(596)
Total Comprehensive Income (Loss), net of tax									1,634	(94)	1,256
Less: comprehensive income—noncontrolling interests									330	251	194
Comprehensive Income (Loss)—Controlling Interests									$ 1,304	$ (345)	$ 1,062

Condensed Consolidating Balance

Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		$ 305	$ 213	$ 215	$ 201
Receivables - consolidated subsidiaries		0	0
Notes receivable From Consolidated Subsidiaries current		0	0
Receivables (net of allowance for doubtful accounts of $10 and $11 at December 31, 2016 and 2015, respectively)		1,003	806
Other current assets		464	629
Total current assets		1,772	1,648
Investments in and loans to unconsolidated affiliates		2,780	2,592
Investments in consolidated subsidiaries		0	0
Advances receivable - consolidated subsidiaries		0	0
Notes receivable - consolidated subsidiaries		0	0
Goodwill		4,181	4,154	4,714
Other assets		393	310
Net property, plant and equipment		26,208	22,918
Regulatory Assets and Deferred Debits		1,508	1,301
Total Assets		36,842	32,923	33,998
Accounts payable		828	511
Accounts payable - consolidated subsidiaries		0	0
Commercial paper	[1],[2]	1,453	1,112
Short-term borrowings - consolidated subsidiaries		0	0
Taxes accrued		86	78
Current maturities of long-term debt		551	652
Other current liabilities		987	1,039
Total current liabilities		3,905	3,392
Long-term debt		13,624	12,892
Advances payable - consolidated subsidiaries		0	0
Notes payable—consolidated subsidiaries		0	0
Deferred credits and other liabilities		7,212	6,768
Preferred stock of subsidiaries		562	339
Equity
Total controlling interests		7,157	6,526
Noncontrolling interests		4,382	3,006
Total equity		11,539	9,532	10,398	10,323
Total Liabilities and Equity		36,842	32,923
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		0	0	0	0
Receivables - consolidated subsidiaries		(4)	(34)
Notes receivable From Consolidated Subsidiaries current		(388)	(387)
Receivables (net of allowance for doubtful accounts of $10 and $11 at December 31, 2016 and 2015, respectively)		0	0
Other current assets		0	0
Total current assets		(392)	(421)
Investments in and loans to unconsolidated affiliates		0	0
Investments in consolidated subsidiaries		(26,982)	(33,080)
Advances receivable - consolidated subsidiaries		(720)	(6,599)
Notes receivable - consolidated subsidiaries		(2,800)	(2,800)
Goodwill		0	0
Other assets		0	0
Net property, plant and equipment		0	0
Regulatory Assets and Deferred Debits		0	0
Total Assets		(30,894)	(42,900)
Accounts payable		0	0
Accounts payable - consolidated subsidiaries		(4)	(34)
Commercial paper		0	0
Short-term borrowings - consolidated subsidiaries		(388)	(387)
Taxes accrued		0	0
Current maturities of long-term debt		0	0
Other current liabilities		0	0
Total current liabilities		(392)	(421)
Long-term debt		0	0
Advances payable - consolidated subsidiaries		(720)	(6,599)
Notes payable—consolidated subsidiaries		(2,800)	(2,800)
Deferred credits and other liabilities		0	0
Preferred stock of subsidiaries		0	0
Equity
Total controlling interests		(26,982)	(33,080)
Noncontrolling interests		0	0
Total equity		(26,982)	(33,080)
Total Liabilities and Equity		(30,894)	(42,900)
Spectra Energy Corp
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		0	0	0	0
Receivables - consolidated subsidiaries		2	15
Notes receivable From Consolidated Subsidiaries current		0	0
Receivables (net of allowance for doubtful accounts of $10 and $11 at December 31, 2016 and 2015, respectively)		1	2
Other current assets		16	25
Total current assets		19	42
Investments in and loans to unconsolidated affiliates		0	0
Investments in consolidated subsidiaries		8,403	13,919
Advances receivable - consolidated subsidiaries		0	0
Notes receivable - consolidated subsidiaries		0	0
Goodwill		0	0
Other assets		86	41
Net property, plant and equipment		0	0
Regulatory Assets and Deferred Debits		3	3
Total Assets		8,511	14,005
Accounts payable		3	2
Accounts payable - consolidated subsidiaries		0	4
Commercial paper		0	0
Short-term borrowings - consolidated subsidiaries		0	0
Taxes accrued		2	5
Current maturities of long-term debt		0	0
Other current liabilities		92	102
Total current liabilities		97	113
Long-term debt		0	0
Advances payable - consolidated subsidiaries		499	6,599
Notes payable—consolidated subsidiaries		0	0
Deferred credits and other liabilities		758	767
Preferred stock of subsidiaries		0	0
Equity
Total controlling interests		7,157	6,526
Noncontrolling interests		0	0
Total equity		7,157	6,526
Total Liabilities and Equity		8,511	14,005
Spectra Energy Capital, LLC
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		10	1	1	12
Receivables - consolidated subsidiaries		0	6
Notes receivable From Consolidated Subsidiaries current		0	0
Receivables (net of allowance for doubtful accounts of $10 and $11 at December 31, 2016 and 2015, respectively)		1	0
Other current assets		2	0
Total current assets		13	7
Investments in and loans to unconsolidated affiliates		0	0
Investments in consolidated subsidiaries		18,579	19,161
Advances receivable - consolidated subsidiaries		720	5,273
Notes receivable - consolidated subsidiaries		0	0
Goodwill		0	0
Other assets		18	27
Net property, plant and equipment		0	0
Regulatory Assets and Deferred Debits		10	3
Total Assets		19,340	24,471
Accounts payable		2	3
Accounts payable - consolidated subsidiaries		4	28
Commercial paper		631	481
Short-term borrowings - consolidated subsidiaries		388	387
Taxes accrued		0	0
Current maturities of long-term debt		0	0
Other current liabilities		51	48
Total current liabilities		1,076	947
Long-term debt		2,886	2,891
Advances payable - consolidated subsidiaries		0	0
Notes payable—consolidated subsidiaries		2,800	2,800
Deferred credits and other liabilities		4,175	3,914
Preferred stock of subsidiaries		0	0
Equity
Total controlling interests		8,403	13,919
Noncontrolling interests		0	0
Total equity		8,403	13,919
Total Liabilities and Equity		19,340	24,471
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash and cash equivalents		295	212	$ 214	$ 189
Receivables - consolidated subsidiaries		2	13
Notes receivable From Consolidated Subsidiaries current		388	387
Receivables (net of allowance for doubtful accounts of $10 and $11 at December 31, 2016 and 2015, respectively)		1,001	804
Other current assets		446	604
Total current assets		2,132	2,020
Investments in and loans to unconsolidated affiliates		2,780	2,592
Investments in consolidated subsidiaries		0	0
Advances receivable - consolidated subsidiaries		0	1,326
Notes receivable - consolidated subsidiaries		2,800	2,800
Goodwill		4,181	4,154
Other assets		289	242
Net property, plant and equipment		26,208	22,918
Regulatory Assets and Deferred Debits		1,495	1,295
Total Assets		39,885	37,347
Accounts payable		823	506
Accounts payable - consolidated subsidiaries		0	2
Commercial paper		822	631
Short-term borrowings - consolidated subsidiaries		0	0
Taxes accrued		84	73
Current maturities of long-term debt		551	652
Other current liabilities		844	889
Total current liabilities		3,124	2,753
Long-term debt		10,738	10,001
Advances payable - consolidated subsidiaries		221	0
Notes payable—consolidated subsidiaries		0	0
Deferred credits and other liabilities		2,279	2,087
Preferred stock of subsidiaries		562	339
Equity
Total controlling interests		18,579	19,161
Noncontrolling interests		4,382	3,006
Total equity		22,961	22,167
Total Liabilities and Equity		$ 39,885	$ 37,347
[1]	The weighted-average days to maturity was 14 days as of December 31, 2016 and 12 days as of December 31, 2015.
[2]	Weighted-average rate on outstanding commercial paper was 1.08% at December 31, 2016 and 0.9% at December 31, 2015.

Condensed Consolidating Stat154

Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 208	$ 281	$ 221	$ 310	$ (188)	$ 243	$ 80	$ 325	$ 1,020	$ 460	$ 1,283
Depreciation and amortization									799	778	809
Impairment charges									0	349	0
Gain (Loss) on Sales of Other Assets and Other, net									26	(4)	1
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Earnings) loss from equity investments									(97)	290	(361)
Equity in earnings of consolidated subsidiaries									0	0	0
Distributions from equity investments									111	161	380
Other									167	213	109
Net cash provided by operating activities									2,026	2,247	2,221
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures									(3,623)	(2,848)	(2,028)
Investments in and loans to unconsolidated affiliates									(251)	(124)	(259)
Purchase of intangible, net									(80)	0	0
Dispositions									207	0	0
Purchases of held-to-maturity securities									(633)	(668)	(790)
Proceeds from sales and maturities of held-to-maturity securities									670	695	815
Purchases of available-for-sale securities									(738)	(95)	(13)
Proceeds from sales and maturities of available-for-sale securities									735	87	7
Distributions from equity investments									50	451	266
Repayment of loan to equity investment									0	0	0
Distribution to equity investment									(148)	(248)	0
Other changes in restricted funds									(20)	(33)	(1)
Other									1	1	0
Net cash used in investing activities									(3,830)	(2,782)	(2,003)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt									1,183	1,585	1,028
Payments for the redemption of long-term debt									(652)	(285)	(1,184)
Net increase (decrease) in commercial paper									319	(439)	574
Distributions to noncontrolling interests									(246)	(198)	(175)
Contributions from noncontrolling interests									743	248	145
Proceeds from the issuances of Spectra Energy common stock									879	0	0
Proceeds from the issuance of Spectra Energy Partners common units									579	546	327
Proceeds from the issuance of Westcoast Energy Inc. preferred stock									229	84	0
Dividends paid on common stock									(1,127)	(996)	(925)
Distributions and advances from (to) affiliates									0	0	0
Other									(17)	(5)	11
Net cash provided by (used in) financing activities									1,890	540	(199)
Effect of exchange rate changes on cash									6	(7)	(5)
Net increase (decrease) in cash and cash equivalents									92	(2)	14
Cash and cash equivalents at beginning of period				213				215	213	215	201
Cash and cash equivalents at end of period	305				213				305	213	215
Eliminations
CASH FLOWS FROM OPERATING ACTIVITIES
Net income									(1,837)	(734)	(2,705)
Depreciation and amortization									0	0	0
Impairment charges										0
Gain (Loss) on Sales of Other Assets and Other, net									0	0	0
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Earnings) loss from equity investments									0	0	0
Equity in earnings of consolidated subsidiaries									1,837	734	2,705
Distributions from equity investments									0	0	0
Other									0	0	0
Net cash provided by operating activities									0	0	0
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures									0	0	0
Investments in and loans to unconsolidated affiliates									0	0	0
Purchase of intangible, net									0
Dispositions									0
Purchases of held-to-maturity securities									0	0	0
Proceeds from sales and maturities of held-to-maturity securities									0	0	0
Purchases of available-for-sale securities									0	0	0
Proceeds from sales and maturities of available-for-sale securities									0	0	0
Distributions from equity investments									0	0	0
Repayment of loan to equity investment									(68)	(56)	(587)
Distribution to equity investment									0	0
Other changes in restricted funds									0	0	0
Other									0	0
Net cash used in investing activities									(68)	(56)	(587)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt									0	0	0
Payments for the redemption of long-term debt									0	0	0
Net increase (decrease) in commercial paper									0	0	0
Distributions to noncontrolling interests									0	0	0
Contributions from noncontrolling interests									0	0	0
Proceeds from the issuances of Spectra Energy common stock									0
Proceeds from the issuance of Spectra Energy Partners common units									0	0	0
Proceeds from the issuance of Westcoast Energy Inc. preferred stock									0	0
Dividends paid on common stock									0	0	0
Distributions and advances from (to) affiliates									68	56	587
Other									0	0	0
Net cash provided by (used in) financing activities									68	56	587
Effect of exchange rate changes on cash									0	0	0
Net increase (decrease) in cash and cash equivalents									0	0	0
Cash and cash equivalents at beginning of period				0				0	0	0	0
Cash and cash equivalents at end of period	0				0				0	0	0
Spectra Energy Corp
CASH FLOWS FROM OPERATING ACTIVITIES
Net income									693	196	1,082
Depreciation and amortization									0	0	0
Impairment charges										0
Gain (Loss) on Sales of Other Assets and Other, net									0	0	0
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Earnings) loss from equity investments									0	0	0
Equity in earnings of consolidated subsidiaries									(671)	(161)	(1,054)
Distributions from equity investments									0	0	0
Other									(51)	187	14
Net cash provided by operating activities									(29)	222	42
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures									0	0	0
Investments in and loans to unconsolidated affiliates									0	0	0
Purchase of intangible, net									0
Dispositions									0
Purchases of held-to-maturity securities									0	0	0
Proceeds from sales and maturities of held-to-maturity securities									0	0	0
Purchases of available-for-sale securities									0	0	0
Proceeds from sales and maturities of available-for-sale securities									0	0	0
Distributions from equity investments									0	0	0
Repayment of loan to equity investment									(50)	(240)	92
Distribution to equity investment									0	0
Other changes in restricted funds									0	0	0
Other									0	0
Net cash used in investing activities									(50)	(240)	92
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt									0	0	0
Payments for the redemption of long-term debt									0	0	0
Net increase (decrease) in commercial paper									0	0	0
Distributions to noncontrolling interests									0	0	0
Contributions from noncontrolling interests									0	0	0
Proceeds from the issuances of Spectra Energy common stock									879
Proceeds from the issuance of Spectra Energy Partners common units									0	0	0
Proceeds from the issuance of Westcoast Energy Inc. preferred stock									0	0
Dividends paid on common stock									(1,127)	(996)	(925)
Distributions and advances from (to) affiliates									316	1,018	777
Other									11	(4)	14
Net cash provided by (used in) financing activities									79	18	(134)
Effect of exchange rate changes on cash									0	0	0
Net increase (decrease) in cash and cash equivalents									0	0	0
Cash and cash equivalents at beginning of period				0				0	0	0	0
Cash and cash equivalents at end of period	0				0				0	0	0
Spectra Energy Capital, LLC
CASH FLOWS FROM OPERATING ACTIVITIES
Net income									671	161	1,054
Depreciation and amortization									0	0	0
Impairment charges										0
Gain (Loss) on Sales of Other Assets and Other, net									0	0	0
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Earnings) loss from equity investments									0	0	0
Equity in earnings of consolidated subsidiaries									(1,166)	(573)	(1,651)
Distributions from equity investments									0	0	0
Other									268	33	304
Net cash provided by operating activities									(227)	(379)	(293)
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures									0	0	0
Investments in and loans to unconsolidated affiliates									0	0	0
Purchase of intangible, net									0
Dispositions									0
Purchases of held-to-maturity securities									0	0	0
Proceeds from sales and maturities of held-to-maturity securities									0	0	0
Purchases of available-for-sale securities									0	0	0
Proceeds from sales and maturities of available-for-sale securities									0	0	0
Distributions from equity investments									0	0	0
Repayment of loan to equity investment									118	296	495
Distribution to equity investment									0	0
Other changes in restricted funds									0	0	0
Other									0	0
Net cash used in investing activities									118	296	495
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt									0	0	300
Payments for the redemption of long-term debt									0	0	(557)
Net increase (decrease) in commercial paper									150	83	54
Distributions to noncontrolling interests									0	0	0
Contributions from noncontrolling interests									0	0	0
Proceeds from the issuances of Spectra Energy common stock									0
Proceeds from the issuance of Spectra Energy Partners common units									0	0	0
Proceeds from the issuance of Westcoast Energy Inc. preferred stock									0	0
Dividends paid on common stock									0	0	0
Distributions and advances from (to) affiliates									(23)	0	(10)
Other									(9)	0	0
Net cash provided by (used in) financing activities									118	83	(213)
Effect of exchange rate changes on cash									0	0	0
Net increase (decrease) in cash and cash equivalents									9	0	(11)
Cash and cash equivalents at beginning of period				1				1	1	1	12
Cash and cash equivalents at end of period	10				1				10	1	1
Non-Guarantor Subsidiaries
CASH FLOWS FROM OPERATING ACTIVITIES
Net income									1,493	837	1,852
Depreciation and amortization									799	778	809
Impairment charges										349
Gain (Loss) on Sales of Other Assets and Other, net									26	(4)	1
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
(Earnings) loss from equity investments									(97)	290	(361)
Equity in earnings of consolidated subsidiaries									0	0	0
Distributions from equity investments									111	161	380
Other									(50)	(7)	(209)
Net cash provided by operating activities									2,282	2,404	2,472
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures									(3,623)	(2,848)	(2,028)
Investments in and loans to unconsolidated affiliates									(251)	(124)	(259)
Purchase of intangible, net									(80)
Dispositions									207
Purchases of held-to-maturity securities									(633)	(668)	(790)
Proceeds from sales and maturities of held-to-maturity securities									670	695	815
Purchases of available-for-sale securities									(738)	(95)	(13)
Proceeds from sales and maturities of available-for-sale securities									735	87	7
Distributions from equity investments									50	451	266
Repayment of loan to equity investment									0	0	0
Distribution to equity investment									(148)	(248)
Other changes in restricted funds									(20)	(33)	(1)
Other									1	1
Net cash used in investing activities									(3,830)	(2,782)	(2,003)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt									1,183	1,585	728
Payments for the redemption of long-term debt									(652)	(285)	(627)
Net increase (decrease) in commercial paper									169	(522)	520
Distributions to noncontrolling interests									(246)	(198)	(175)
Contributions from noncontrolling interests									743	248	145
Proceeds from the issuances of Spectra Energy common stock									0
Proceeds from the issuance of Spectra Energy Partners common units									579	546	327
Proceeds from the issuance of Westcoast Energy Inc. preferred stock									229	84
Dividends paid on common stock									0	0	0
Distributions and advances from (to) affiliates									(361)	(1,074)	(1,354)
Other									(19)	(1)	(3)
Net cash provided by (used in) financing activities									1,625	383	(439)
Effect of exchange rate changes on cash									6	(7)	(5)
Net increase (decrease) in cash and cash equivalents									83	(2)	25
Cash and cash equivalents at beginning of period				$ 212				$ 214	212	214	189
Cash and cash equivalents at end of period	$ 295				$ 212				$ 295	$ 212	$ 214

Quarterly Financial Data (Un155

Quarterly Financial Data (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Operating revenues	$ 1,298		$ 1,075		$ 1,159		$ 1,384		$ 1,316		$ 1,103		$ 1,192		$ 1,623		$ 4,916		$ 5,234		$ 5,903
Operating Income	373		321		371		494		97		389		406		541		1,559		1,433		1,924
Net income	208		281		221		310		(188)		243		80		325		1,020		460		1,283
Net Income—Controlling Interests	$ 115		$ 195		$ 149		$ 234		$ (263)		$ 174		$ 18		$ 267		$ 693		$ 196		$ 1,082
Earnings per share
Basic and diluted	$ 0.16	[1]	$ 0.28	[1]	$ 0.21	[1]	$ 0.35	[1]	$ (0.39)	[1]	$ 0.26	[1]	$ 0.03	[1]	$ 0.40	[1]	$ 1	[1]	$ 0.29	[1]	$ 1.61
[1]	Quarterly earnings-per-share amounts are stand-alone calculations and may not be additive to full-year amounts due to rounding.

Quarterly Financial Data (Un156

Quarterly Financial Data (Unaudited) - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, Impairment Loss	$ 0	$ 333	$ 0
Impairment charges	0	349	0
Earnings (loss) from equity investments	97	(290)	361
DCP Midstream, LLC | Goodwill and Asset Impairment
Goodwill [Line Items]
Earnings (loss) from equity investments		(231)
DCP Midstream, LLC
Goodwill [Line Items]
Goodwill, Impairment Loss		460
Impairment charges		342
Western Canada Transmission & Processing
Goodwill [Line Items]
Goodwill, Impairment Loss		333
Earnings (loss) from equity investments	$ 3	2	$ 1
Western Canada Transmission & Processing | BC Pipeline and BC Field Services
Goodwill [Line Items]
Goodwill, Impairment Loss		270
Western Canada Transmission & Processing | Empress
Goodwill [Line Items]
Goodwill, Impairment Loss		$ 63

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts and Reserves (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		$ 145	$ 124	$ 174
Additions Charged to Expense		51	43	35
Additions Charged to Other Accounts		8	24	0
Deductions	[1]	81	46	85
Balance at End of Period		123	145	124
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		11	11	10
Additions Charged to Expense		9	7	6
Additions Charged to Other Accounts		0	0	0
Deductions	[1]	10	7	5
Balance at End of Period		10	11	11
Other (b)
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	[2]	134	113	164
Additions Charged to Expense	[2]	42	36	29
Additions Charged to Other Accounts	[2]	8	24	0
Deductions	[1],[2]	71	39	80
Balance at End of Period	[2]	$ 113	$ 134	$ 113
[1]	Principally cash payments and reserve reversals.
[2]	Principally income tax, insurance-related, litigation and other reserves, included primarily in Deferred Credits and Other Liabilities—Regulatory and Other on the Consolidated Balance Sheets.