Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping

Estimated fair values of the Company's outstanding debt were:

		December 31, 2018				December 31, 2017
	Fair value hierarchy	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt (including current maturities):		(Millions)
Term loans and senior notes	Level 2	$	5,307	$	5,218	$	1,346	$	1,383

The following table presents assets and liabilities included in the Company's consolidated balance sheets as of December 31, 2018 and 2017 that are recognized at fair value on a recurring basis, and indicate the fair value hierarchy utilized to determine such fair value:

		December 31, 2018						December 31, 2017
	Fair value hierarchy	Carrying Amount			Fair Value			Carrying Amount		Fair Value
Derivative instruments:		(Millions)
Equity swap agreement	Level 2	$	4		$	4		$	4	$	4
Commodity contracts	Level 2	$	(2	)	$	(2	)	$	—	$	—