Fair Value (Tables)

12 Months Ended

Dec. 31, 2017

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following two tables summarize the fair value measurements of our (i) energy commodity derivative contracts; (ii) interest rate swap agreements; and (iii) cross-currency swap agreements, based on the three levels established by the Codification (in millions). The tables also identify the impact of derivative contracts which we have elected to present on our accompanying consolidated balance sheets on a gross basis that are eligible for netting under master netting agreements.



	Balance sheet asset fair value measurements by level
	Level 1		Level 2		Level 3		Gross amount		Contracts available for netting			Cash collateral held(b)			Net amount
As of December 31, 2017
Energy commodity derivative contracts(a)	$	17	$	70	$	—	$	87	$	(42	)	$	(12	)	$	33
Interest rate swap agreements	$	—	$	205	$	—	$	205	$	(15	)	$	—		$	190
Cross-currency swap agreements	$	—	$	166	$	—	$	166	$	(6	)	$	—		$	160
As of December 31, 2016
Energy commodity derivative contracts(a)	$	6	$	168	$	—	$	174	$	(43	)	$	—		$	131
Interest rate swap agreements	$	—	$	300	$	—	$	300	$	(18	)	$	—		$	282



	Balance sheet liability fair value measurements by level
	Level 1			Level 2			Level 3		Gross amount			Contracts available for netting		Collateral posted(b)		Net amount
As of December 31, 2017
Energy commodity derivative contracts(a)	$	(3	)	$	(98	)	$	—	$	(101	)	$	42	$	—	$	(59	)
Interest rate swap agreements	$	—		$	(65	)	$	—	$	(65	)	$	15	$	—	$	(50	)
Cross-currency swap agreements	$	—		$	(6	)	$	—	$	(6	)	$	6	$	—	$	—
As of December 31, 2016
Energy commodity derivative contracts(a)	$	(29	)	$	(82	)	$	—	$	(111	)	$	43	$	37	$	(31	)
Interest rate swap agreements	$	—		$	(57	)	$	—	$	(57	)	$	18	$	—	$	(39	)
Cross-currency swap agreements	$	—		$	(31	)	$	—	$	(31	)	$	—	$	—	$	(31	)

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(a)	Level 1 consists primarily of NYMEX natural gas futures. Level 2 consists primarily of OTC WTI swaps and NGL swaps.


(b)	Any cash collateral paid or received is reflected in this table, but only to the extent that it represents variation margins. Any amount associated with derivative prepayments or initial margins that are not influenced by the derivative asset or liability amounts or those that are determined solely on their volumetric notional amounts are excluded from this table.

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation

The table below provides a summary of changes in the fair value of our Level 3 energy commodity derivative contracts (in millions):

Significant unobservable inputs (Level 3)

	Year Ended December 31,
	2017		2016
Derivatives-net asset (liability)
Beginning of period	$	—	$	(15	)
Total gains or (losses) included in earnings	—		(9		)
Settlements	—		24
End of period	$	—	$	—
The amount of total gains or (losses) for the period included in earnings attributable to the change in unrealized gains or (losses) relating to assets held at the reporting date	$	—	$	—

Fair Value, by Balance Sheet Grouping

The carrying value and estimated fair value of our outstanding debt balances is disclosed below (in millions):



	December 31, 2017				December 31, 2016
	Carrying value		Estimated fair value		Carrying value		Estimated fair value
Total debt	$	37,843	$	40,050	$	40,050	$	41,015