Debt and Credit Facilities (Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term debt, Gross	$ 1,834	$ 1,492
Other long-term debt	45	50
Adjustments, primarily unamortized gains on interest rate swap terminations	29	43
Less: current portion	(4)	(405)
Long-term debt	1,859	1,130
5.375% Senior Notes Due 2012 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	0	400
Long-term debt, interest rate	5.375%
Long-term debt, maturity year	2012
6.0% Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	399	399
Long-term debt, interest rate	6.00%
Long-term debt, maturity year	2017
3.75% Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	747	0
Long-term debt, interest rate	3.75%
Long-term debt, maturity year	2022
6.5% Debentures Due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	118	118
Long-term debt, interest rate	6.50%
Long-term debt, maturity year	2025
7.5% Debentures Due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	346	346
Long-term debt, interest rate	7.50%
Long-term debt, maturity year	2025
6.5% Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	36	36
Long-term debt, interest rate	6.50%
Long-term debt, maturity year	2028
6.625% Senior Notes Due 2037 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	54	54
Long-term debt, interest rate	6.625%
Long-term debt, maturity year	2037
5.22% Debentures Due 2097 [Member]
Debt Instrument [Line Items]
Long-term debt, Gross	$ 89	$ 89
Long-term debt, interest rate	5.22%
Long-term debt, maturity year	2097