Reclassifications From Accumulated Other Comprehensive Income (Loss) (Components Of Accumulated Other Comprehensive Income (Loss)) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, December 31, 2016	$ (39)
Other comprehensive income (loss) before reclassifications
Amounts reclassified from other comprehensive income (loss)
Net current-period other comprehensive income (loss)
Ending balance, March 31, 2017	(39)
Pension And Other Postretirement [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, December 31, 2016	(19)
Other comprehensive income (loss) before reclassifications
Amounts reclassified from other comprehensive income (loss)
Net current-period other comprehensive income (loss)
Ending balance, March 31, 2017	(19)
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, December 31, 2016	(20)
Other comprehensive income (loss) before reclassifications
Amounts reclassified from other comprehensive income (loss)
Net current-period other comprehensive income (loss)
Ending balance, March 31, 2017	$ (20)