Benefit Obligations (Schedule of Company Commitments to Fund Benefit Obligations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to pension plans	$ 56
Expected employer contributions to pension plans in current fiscal year	160
Nonqualified Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to pension plans	4
Expected employer contributions to pension plans in current fiscal year	15
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions to pension plans	7
Expected employer contributions to pension plans in current fiscal year	$ 25