CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Statement of Comprehensive Income [Abstract]
Reclassification of previously deferred derivative losses to net income, income tax benefit (expense)	$ (1)	$ (1)	$ (3)	$ (4)
Amortization of net actuarial loss and prior service cost to net periodic benefit cost, income tax benefit (expense)	$ (8)	$ (8)	$ (25)	$ (24)