Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2015

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, 2015 and 2014 were as follows:

	December 31, 2015				December 31, 2014
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
	(Millions)
Long-term debt (including current maturities)	$	1,125	$	1,160	$	1,057	$	1,106
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, 2015 (all of which mature in 2016):

		Notional Amount in Foreign Currency
		(Millions)
Australian dollars	—Purchase	1
British pounds	—Purchase	45
	—Sell	(43	)
Canadian dollars	—Sell	(2	)
European euro	—Sell	(16	)
Japanese yen	—Purchase	50
	—Sell	(1,153	)
South African rand	—Purchase	80
U.S. dollars	—Purchase	93
	—Sell	(71	)