Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive income (loss) by component
Balance at December 31, 2014	$ (2,017)	$ (802)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	(32)	(1,284)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	115	69
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	83	(1,215)
Balance at December 31, 2015	(1,934)	(2,017)
Foreign Currency Translation Adjustment and Other
Accumulated other comprehensive income (loss) by component
Balance at December 31, 2014	(25)	(11)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	(14)	(15)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	0	1
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(14)	(14)
Balance at December 31, 2015	(39)	(25)
Defined Benefit Plans | Pension Plan
Accumulated other comprehensive income (loss) by component
Balance at December 31, 2014	(1,720)	(669)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	(98)	(1,107)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	103	56
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	5	(1,051)
Balance at December 31, 2015	(1,715)	(1,720)
Defined Benefit Plans | Post-Retirement Benefit Plans
Accumulated other comprehensive income (loss) by component
Balance at December 31, 2014	(272)	(122)
OCI, before Reclassifications, Net of Tax, Attributable to Parent	80	(162)
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	12	12
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	92	(150)
Balance at December 31, 2015	$ (180)	$ (272)