Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Face (par) amount of debt instrument at time of issuance.

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

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Gross amount of debt extinguished.

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Debt Instrument, Bonds, Principal Amount Remarketed

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The calculated fixed charge coverage ratio.

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Maximum distribution percentage of specified net cash proceeds received after a stated period plus other adjustments, and subject to certain other distribution terms.

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Maximum percentage of income distribution, subject to certain other distribution terms.

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The maximum unrestricted distribution allowed under debt covenants. Distributions in excess of this amount are subject to certain restrictions.

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The maximum unrestricted payment per share allowed under debt covenants for the quarterly dividend.

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Long-Term Debt (GO Zone Bonds) (Details) $ in Millions		12 Months Ended
Long-Term Debt (GO Zone Bonds) (Details) $ in Millions	Nov. 01, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Dec. 31, 2010 USD ($)	Jul. 02, 2010 USD ($)	Dec. 13, 2007 USD ($)
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 2,715	$ 3,853
Senior Notes [Member] \| 6 1/2% GO Zone Senior Notes Due 2035 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 89	89		$ 89
Debt Instrument, Face Amount					$ 89
Stated interest rate (percent)		6.50%
Senior Notes [Member] \| 6.75% Go Zone Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount							$ 250
Extinguishment of Debt, Amount	$ 250
Senior Notes [Member] \| Go Zone 3.50% Bonds Due 2032 [Member]
Debt Instrument [Line Items]
Amount of bonds remarketed				$ 250
Stated interest rate (percent)				3.50%
Senior Notes [Member] \| 6 1/2% GO Zone Senior Notes Due 2029 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 100	100
Debt Instrument, Face Amount						$ 100
Stated interest rate (percent)		6.50%
Senior Notes [Member] \| 3.50% Senior Notes Due 2032 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 250	$ 250
Stated interest rate (percent)		3.50%
Fixed Charge Coverage Ratio		2.0	2.0
Maximum Unrestricted Quarterly Dividends Allowable Under Debt Covenants		0.10
Maximum Unrestricted Distributions Allowable Under Debt Covenants		$ 100
Maximum Percentage Of Income Distribution		50.00%
Maximum Distribution Percentage Of Specified Net Cash Proceeds		100.00%
Senior Notes [Member] \| Loan related to tax-exempt waste disposal revenue bonds due 2027 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross		$ 11	$ 11