Supplemental Balance Sheet Information (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	$ 24	$ (233)	$ (174)
Other comprehensive income (loss) before reclassifications	(355)	234	(64)
Less: Amounts reclassified from AOCI, net of tax	7	(23)	(5)
Other comprehensive income (loss), net of tax	(362)	257	(59)
Accumulated other comprehensive income (loss), net of tax, ending balance	(338)	24	(233)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	35	32	28
Other comprehensive income (loss) before reclassifications	(15)	4	(5)
Less: Amounts reclassified from AOCI, net of tax	4	1	(9)
Other comprehensive income (loss), net of tax	(19)	3	4
Accumulated other comprehensive income (loss), net of tax, ending balance	16	35	32
Pension and Other Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	(32)	(303)	(221)
Other comprehensive income (loss) before reclassifications	(272)	247	(81)
Less: Amounts reclassified from AOCI, net of tax	(2)	(24)	1
Other comprehensive income (loss), net of tax	(270)	271	(82)
Accumulated other comprehensive income (loss), net of tax, ending balance	(302)	(32)	(303)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), net of tax, beginning balance	21	38	19
Other comprehensive income (loss) before reclassifications	(68)	(17)	22
Less: Amounts reclassified from AOCI, net of tax	5	0	3
Other comprehensive income (loss), net of tax	(73)	(17)	19
Accumulated other comprehensive income (loss), net of tax, ending balance	$ (52)	$ 21	$ 38