Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2016

Disclosure Financial Instruments Additional Information [Abstract]

Carrying and Estimated Fair Value

The carrying and estimated fair values of our financial instruments by class at December 31, 2016 and 2015 were as follows:

	December 31, 2016				December 31, 2015
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(Millions)
Long-term debt (including current maturities)	$	1,297	$	1,311	$	1,125	$	1,160
Instruments with off-balance sheet risk:
Foreign exchange forward contracts:
Asset derivative contracts	—		—		1		1

Summarization for Foreign Currency Forward Purchase and Sale Contracts

The following table summarizes by major currency the notional amounts for foreign currency forward purchase and sale contracts as of December 31, 2016 (all of which mature in 2017):

		Notional Amount in Foreign Currency
		(Millions)
British pounds	—Purchase	9
Canadian dollars	—Sell	(2	)
European euro	—Purchase	21
	—Sell	(3	)
Japanese yen	—Purchase	388
	—Sell	(60	)
South African rand	—Purchase	131
	—Sell	(17	)
U.S. dollars	—Purchase	5
	—Sell	(45	)