Supplemental Balance Sheet Information - Changes in Balances of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	$ (338)	$ 24	$ (233)
Other comprehensive income (loss) before reclassifications	2	(355)	234
Less: Amounts reclassified from AOCI, net of tax	(22)	7	(23)
Other comprehensive income (loss), net of tax	24	(362)	257
Balance at end of period	(314)	(338)	24
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	16	35	32
Other comprehensive income (loss) before reclassifications	(5)	(15)	4
Less: Amounts reclassified from AOCI, net of tax	(9)	4	1
Other comprehensive income (loss), net of tax	4	(19)	3
Balance at end of period	20	16	35
Pension and Other Postretirement Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(302)	(32)	(303)
Other comprehensive income (loss) before reclassifications	74	(272)	247
Less: Amounts reclassified from AOCI, net of tax	(7)	(2)	(24)
Other comprehensive income (loss), net of tax	81	(270)	271
Balance at end of period	(221)	(302)	(32)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(52)	21	38
Other comprehensive income (loss) before reclassifications	(67)	(68)	(17)
Less: Amounts reclassified from AOCI, net of tax	(6)	5	0
Other comprehensive income (loss), net of tax	(61)	(73)	(17)
Balance at end of period	$ (113)	$ (52)	$ 21