CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE OPERATIONS (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Income	$ 316	$ 245	$ 251
Related to marketable securities:
Unrealized holding gains (losses) arising during the period	9	(1)	7
Reclassification adjustment for gains included in net income	(7)	(3)	(8)
Income tax benefit (expense)	(1)	1	0
Marketable securities, net of tax	1	(3)	(1)
Related to employee benefit plans:
Amortization of net actuarial items and prior service cost arising during period	(68)	(175)	(31)
Income tax benefit	25	65	12
Employee benefit plans, net of tax	(43)	(110)	(19)
Related to interest rate derivative instruments:
Unrealized holding losses arising during the period	(4)	(20)	(11)
Income tax benefit	0	10	4
Interest rate derivative instruments, net of tax	(4)	(10)	(7)
Other comprehensive loss	(46)	(123)	(27)
Comprehensive income	$ 270	$ 122	$ 224