Debt and Capital Lease Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Debt Instruments
Net unamortized discount, including fair value adjustments	$ (24)	$ (21)
Total debt	7,292	6,354
Capital lease obligations, including unamortized fair value adjustments	85	32
Total debt and capital lease obligations	7,377	6,386
Less current portion	(127)	(606)
Debt and capital lease obligations, less current portion	7,250	5,780
Bank Credit Facilities [Member] \| Credit Facilities [Member]
Debt Instruments
Long-term debt at stated values	$ 175	0
Senior Notes Due in 2025 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	3.65%
Long-term debt at stated values	$ 600	0
Senior Notes Due In 2015 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	4.50%
Long-term debt at stated values	$ 0	400
Senior Notes Due in 2045 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	4.90%
Long-term debt at stated values	$ 650	0
Senior Notes Due In June 2017 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	6.125%
Long-term debt at stated values	$ 750	750
Senior Notes Due In 2020 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	6.125%
Long-term debt at stated values	$ 850	850
Senior Notes Due In June 2037 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	6.625%
Long-term debt at stated values	$ 1,500	1,500
Senior Notes Due In October 2037 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	6.75%
Long-term debt at stated values	$ 24	24
Senior Notes Due In October 2017 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	7.20%
Long-term debt at stated values	$ 200	200
Senior Notes Due In 2097 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	7.45%
Long-term debt at stated values	$ 100	100
Senior Notes Due In 2032 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	7.50%
Long-term debt at stated values	$ 750	750
Senior Notes Due In 2030 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	8.75%
Long-term debt at stated values	$ 200	200
Senior Notes Due In 2019 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	9.375%
Long-term debt at stated values	$ 750	750
Senior Notes Due In 2039 [Member] \| Senior Notes [Member]
Debt Instruments
Interest rate of notes in percentage	10.50%
Long-term debt at stated values	$ 250	250
Debenture Due In 2026 [Member] \| Debentures [Member]
Debt Instruments
Interest rate of notes in percentage	7.65%
Long-term debt at stated values	$ 100	100
Debenture Due In 2015 [Member] \| Debentures [Member]
Debt Instruments
Interest rate of notes in percentage	8.75%
Long-term debt at stated values	$ 0	75
Gulf Opportunity Zone Revenue Bonds Series 2010 [Member] \| Revenue Bonds [Member]
Debt Instruments
Interest rate of notes in percentage	4.00%
Long-term debt at stated values	$ 300	300
A/R Sales Facility [Member] \| Credit Facilities [Member]
Debt Instruments
Long-term debt at stated values	100	100
Other Debt [Member] \| Debentures [Member]
Debt Instruments
Long-term debt at stated values	$ 17	$ 26

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6455398&loc=d3e45280-112737

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 7

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- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

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- Definition

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.

+ References

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- Definition

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC
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- Definition

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

+ References

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- Definition

The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 45
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-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28567-108399

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- References

No definition available.

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (SX 210.9-03.16)
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
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-Paragraph 20, 22
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- Definition

Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Publisher SEC
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