Short-term Borrowings and Long-term Debt (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Short-term Debt	[1]	$ 40	$ 53
Debt Instrument, Unamortized Discount (Premium), Net		(34)	(40)
Long-term Debt, Excluding Current Maturities		2,028	2,469
Long-term Debt, Current Maturities	[1]	325	0
Debt, Current	[1]	365	53
Size of Facility		600	600
Long-term Debt, Maturities in 2016		325
Long-term Debt, Maturities in 2017		250
Long-term Debt, Maturities in 2018		300
Long-term Debt, Maturities in 2019		219
Long-term Debt, Maturities in 2020		0
Inventory financing [Member]
Debt Instrument [Line Items]
Short-term Debt	[1]	$ 40	53
Senior Notes 4.50% to 6.625% due 2016 to 2041
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum		4.50%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum		6.625%
Long-term Debt, Gross, Noncurrent		$ 1,843	2,168
Long-term Debt, Gross, Current	[1]	325	0
Commercial Paper [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross, Noncurrent	[2]	219	341
Long-term Debt, Gross, Current	[1],[2]	$ 0	0
Line of Credit [Member]
Debt Instrument [Line Items]
Percentage on limitation of debt to total capitalization under covenant (in hundredths)		65.00%
Ratio of Indebtedness to Net Capital		0.339
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Loans		$ 0	0
Letter of Credit [Member]
Debt Instrument [Line Items]
Loans		2	0
Commercial Paper [Member]
Debt Instrument [Line Items]
Loans	[3]	$ 219	$ 341
Debt, Weighted Average Interest Rate		0.81%	0.68%
London Interbank Offered Rate (LIBOR) [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Interest Rate Description		1.50%

[1] Includes amounts due or exchangeable within one year of the date noted.

[2] Classified as long-term debt because the termination date of the facility that backstops the commercial paper is more than one year from the date noted.

[3] Weighted average interest rate was 0.81% and 0.68% as of December 31, 2015 and 2014, respectively.