Debt and Credit Facilities (Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term debt, gross	$ 3,407us-gaap_DebtInstrumentCarryingAmount	$ 2,440us-gaap_DebtInstrumentCarryingAmount
Other long-term debt	36us-gaap_OtherLongTermDebt	58us-gaap_OtherLongTermDebt
Adjustments for unamortized gains on interest rate swap terminations	(7)	21
Less: current portion	(4)us-gaap_LongTermDebtCurrent	(4)us-gaap_LongTermDebtCurrent
Long-term debt	3,396us-gaap_LongTermDebtNoncurrent	2,457us-gaap_LongTermDebtNoncurrent
6.0% Senior Notes Due 2017
Debt Instrument [Line Items]
Long-term debt, gross	0	399
Long-term debt, interest rate	6.00%	6.00%
Long-term debt, maturity year	2017	2017
3.5% Senior Notes Due 2021
Debt Instrument [Line Items]
Long-term debt, gross	395	0
Long-term debt, interest rate	3.50%	3.50%
Long-term debt, maturity year	2021	2021
3.75% Senior Notes Due 2022
Debt Instrument [Line Items]
Long-term debt, gross	748	747
Long-term debt, interest rate	3.75%	3.75%
Long-term debt, maturity year	2022	2022
3.5% Senior Notes Due 2023
Debt Instrument [Line Items]
Long-term debt, gross	594	593
Long-term debt, interest rate	3.50%	3.50%
Long-term debt, maturity year	2023	2023
4.0% Senior Note Due 2024
Debt Instrument [Line Items]
Long-term debt, gross	589	0
Long-term debt, interest rate	4.00%	4.00%
Long-term debt, maturity year	2024	2024
6.5% Debentures Due 2025
Debt Instrument [Line Items]
Long-term debt, gross	118	118
Long-term debt, interest rate	6.50%	6.50%
Long-term debt, maturity year	2025	2025
7.5% Debentures Due 2025
Debt Instrument [Line Items]
Long-term debt, gross	346	346
Long-term debt, interest rate	7.50%	7.50%
Long-term debt, maturity year	2025	2025
6.5% Debentures Due 2028
Debt Instrument [Line Items]
Long-term debt, gross	36	36
Long-term debt, interest rate	6.50%	6.50%
Long-term debt, maturity year	2028	2028
6.625% Senior Notes Due 2037
Debt Instrument [Line Items]
Long-term debt, gross	54	54
Long-term debt, interest rate	6.625%	6.625%
Long-term debt, maturity year	2037	2037
5.5% Senior Notes Due 2044
Debt Instrument [Line Items]
Long-term debt, gross	400	0
Long-term debt, interest rate	5.50%	5.50%
Long-term debt, maturity year	2044	2044
5.22% Debentures Due 2097
Debt Instrument [Line Items]
Long-term debt, gross	$ 91	$ 89
Long-term debt, interest rate	5.22%	5.22%
Long-term debt, maturity year	2097	2097

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- Definition

Unamortized Gain on Interest Rate Swap Termination

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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 SEC

-Name Regulation S-X (SX)

-Number 210

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- Definition

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

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- Definition

Amount of long-term debt, after unamortized discount or premium, scheduled 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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- Definition

Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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