Reclassifications From Accumulated Other Comprehensive Income (Loss) (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, December 31, 2015	$ (48)
Other comprehensive income (loss) before reclassifications	(4)
Amounts reclassified from other comprehensive income (loss)	13
Net current-period other comprehensive income (loss)	9	$ (110)	$ 66
Ending balance, December 31, 2016	(39)	(48)
Pension And Other Postretirement [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, December 31, 2015	(25)
Other comprehensive income (loss) before reclassifications	(7)
Amounts reclassified from other comprehensive income (loss)	13
Net current-period other comprehensive income (loss)	6
Ending balance, December 31, 2016	(19)	(25)
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, December 31, 2015	(23)
Other comprehensive income (loss) before reclassifications	3
Net current-period other comprehensive income (loss)	3
Ending balance, December 31, 2016	$ (20)	$ (23)