Long-Term Debt and Credit Facilities (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Domestic Revolving Credit Facility 1850 Million Capacity [Member]
Line of credit facility [Line Items]
Maximum borrowing capacity	$ 1,850
Expiration date	November 2016
Domestic Revolving Credit Facility 1600 Million Capacity [Member]
Line of credit facility [Line Items]
Maximum borrowing capacity		1,600
Expiration date	November 2012
Line of Credit [Member]
Line of credit facility [Line Items]
Unused borrowing capacity	2,705
Domestic Revolving Credit Facility 145 Million Capacity [Member]
Line of credit facility [Line Items]
Maximum borrowing capacity	$ 145
Expiration date	November 2012