Schedule II - Valuation And Qualifying Accounts

12 Months Ended

Dec. 31, 2017

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation And Qualifying Accounts

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

			Additions
(millions)	Balance at beginning of period		Charged to costs and expenses			Charged to other accounts		Deductions (a)			Balance at end of period
Year ended December 31, 2017:
Doubtful accounts	$	5	$	2		$	—	$	(1	)	$	6
Cash discounts	3		34			—		(34		)	3
Income tax valuation allowance	51		124			—		—			175
Year ended December 31, 2016:
Doubtful accounts	7		1			—		(3		)	5
Cash discounts	2		34			—		(33		)	3
Income tax valuation allowance	70		—			—		(19		)	51
Year ended December 31, 2015:
Doubtful accounts	14		(6		)	—		(1		)	7
Cash discounts	1		37			—		(36		)	2
Income tax valuation allowance	1,023		—			—		(953		)	70

(a) Reflects receivables written off as related to doubtful accounts, discounts allowed as related to cash discounts and reductions in the income tax valuation allowance.