Amount of short-term debt and current maturity of long-term debt and capital lease obligations due within one year or the normal operating cycle, if longer.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt - Summary (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Sep. 22, 2016	Aug. 18, 2015	May 26, 2015
Debt Instrument [Line Items]
Total debt	$ 3,569	$ 3,564
Less: short-term debt including current maturities	399	0
Long-term debt	3,170	3,564
Senior Notes \| 2.5% Senior Notes, due 2018
Debt Instrument [Line Items]
Senior notes	$ 399	398
Interest rate (as a percent)	2.50%			2.50%
Unamortized debt discount and issuance costs	$ 1
Senior Notes \| 3.3% Senior Notes, due 2020
Debt Instrument [Line Items]
Senior notes	$ 697	696
Interest rate (as a percent)	3.30%			3.30%
Unamortized debt discount and issuance costs	$ 3
Senior Notes \| 4.0% Senior Notes, due 2025
Debt Instrument [Line Items]
Senior notes	$ 692	691
Interest rate (as a percent)	4.00%				4.00%
Unamortized debt discount and issuance costs	$ 8
Senior Notes \| 4.4% Senior Notes, due 2026
Debt Instrument [Line Items]
Senior notes	$ 892	891
Interest rate (as a percent)	4.40%			4.40%
Unamortized debt discount and issuance costs	$ 8
Senior Notes \| 2.95% Senior Notes, due 2027
Debt Instrument [Line Items]
Senior notes	$ 493	492
Interest rate (as a percent)	2.95%		2.95%
Unamortized debt discount and issuance costs	$ 7
Senior Notes \| 6.55% Senior Notes, due 2037
Debt Instrument [Line Items]
Senior notes	$ 396	$ 396
Interest rate (as a percent)	6.55%
Unamortized debt discount and issuance costs	$ 4