Long-Term Debt, Short-Term Debt and Financing Arrangements (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Short-term Debt [Line Items]
Outstanding borrowings at end of year	$ 62	$ 61
Notes Payable Current [Member]
Short-term Debt [Line Items]
Outstanding borrowings at end of year	62	61
Weighted average interest rate on outstanding borrowings at end of year	6.00%	7.80%
Approximate maximum month-end outstanding borrowings during year	178	201
Approximate average month-end outstanding borrowings during year	$ 118	$ 109
Weighted average interest rate on approximate average month-end outstanding borrowings during year	5.60%	5.50%