Debt and Credit Facilities (Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term debt, gross	$ 4,401	$ 4,355
Adjustments for unamortized gains on interest rate swap terminations	(5)	(6)
Less: current portion	(4)	(4)
Long-term debt	$ 4,392	4,345
2.0% Senior Convertible Notes due 2020
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	2.00%
Long-term debt, gross	$ 988	969
3.5% senior notes due 2021
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	3.50%
Long-term debt, gross	$ 395	394
3.75% senior notes due 2022
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	3.75%
Long-term debt, gross	$ 746	745
3.5% senior notes due 2023
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	3.50%
Long-term debt, gross	$ 593	592
4.0% senior notes due 2024
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	4.00%
Long-term debt, gross	$ 588	587
6.5% debentures due 2025
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	6.50%
Long-term debt, gross	$ 117	118
7.5% debentures due 2025
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	7.50%
Long-term debt, gross	$ 345	345
6.5% debentures due 2028
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	6.50%
Long-term debt, gross	$ 36	36
6.625% senior notes due 2037
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	6.625%
Long-term debt, gross	$ 54	54
5.5% senior notes due 2044
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	5.50%
Long-term debt, gross	$ 396	396
5.22% debentures due 2097
Debt Instrument [Line Items]
Debt instrument stated interest rate (percent)	5.22%
Long-term debt, gross	$ 91	90
Other long-term debt
Debt Instrument [Line Items]
Long-term debt, gross	$ 52	$ 29

Unamortized Gain on Interest Rate Swap Termination

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- Definition

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.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

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

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

+ References

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