Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

Fair Values of Certain Financial Liabilities and Other Financial Instruments

The fair value of certain financial liabilities is shown below (in millions):  

	March 31, 2019				December 31, 2018
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial liabilities
Senior notes (Level 1)	$	2,783	$	2,868	$	2,782	$	2,808
Credit facility (Level 2)		1,051		1,056		1,049		1,055