Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following tables present assets and liabilities accounted for at fair value on a recurring basis as of March 31, 2018 and December 31, 2017 by fair value hierarchy level.

	March 31, 2018
(In millions)	Level 1			Level 2			Level 3		Total
Derivative instruments, assets
Commodity (a)	$	—		$	—		$	—	$	—
Derivative instruments, assets	$	—		$	—		$	—	$	—
Derivative instruments, liabilities
Commodity (a)	$	(2	)	$	(182	)	$	—	$	(184	)
Derivative instruments, liabilities	$	(2	)	$	(182	)	$	—	$	(184	)

^(a) Derivative instruments are recorded on a net basis in our balance sheet. See Note 12.

	December 31, 2017
(In millions)	Level 1			Level 2			Level 3		Total
Derivative instruments, assets
Interest rate	$	—		$	—		$	—	$	—
Derivative instruments, assets	$	—		$	—		$	—	$	—
Derivative instruments, liabilities
Commodity (a)	$	(20	)	$	(120	)	$	—	$	(140	)
Derivative instruments, liabilities	$	(20	)	$	(120	)	$	—	$	(140	)

^(a) Derivative instruments are recorded on a net basis in our balance sheet. See Note 12.

Fair Value Measurements, Nonrecurring [Table Text Block]

The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition.

	Three Months Ended March 31,
	2018				2017
(In millions)	Fair Value		Impairment		Fair Value		Impairment
Long-lived assets	$	50	$	8	$	—	$	4

Fair Value, by Balance Sheet Grouping [Table Text Block]

The following table summarizes financial instruments, excluding receivables, payables and derivative financial instruments, and their reported fair values by individual balance sheet line item at March 31, 2018 and December 31, 2017.

	March 31, 2018				December 31, 2017
	Fair		Carrying		Fair		Carrying
(In millions)	Value		Amount		Value		Amount
Financial assets
Current assets (a)	$	15	$	15	$	762	$	761
Other noncurrent assets	129		132		135		137
Total financial assets	$	144	$	147	$	897	$	898
Financial liabilities
Other current liabilities	$	31	$	43	$	32	$	43
Long-term debt, including current portion (b)	5,841		5,527		5,976		5,526
Deferred credits and other liabilities	105		103		110		103
Total financial liabilities	$	5,977	$	5,673	$	6,118	$	5,672

^(a)  December 31, 2017 fair value and carrying amounts included our two notes receivable relating to the sale of our Canadian business; both were paid during the first quarter of 2018, see note 5 for further information.

^(b) Excludes capital leases, debt issuance costs and interest rate swap adjustments.