Comprehensive Income (Loss) (Reclassification Out of AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ (361)	$ 163	$ 163
Tax impact	165	(30)	(48)
Net income (loss)	(196)	133	115
Pension Benefits [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial gains (losses)	(29)	(20)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Pension Benefits [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial gains (losses)	(29)	(20)	(37)
Pension settlement costs			(44)
Income before income taxes	(29)	(20)	(81)
Tax impact	11	7	31
Net income (loss)	(18)	(13)	(50)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Postretirement Costs [Member] | Amortization Of Defined Benefit Cost Items [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Prior-service costs	5	4	6
Actuarial gains (losses)	(8)	(3)	(8)
Income before income taxes	(3)	1	(2)
Tax impact	1		1
Net income (loss)	$ (2)	$ 1	$ (1)