Stockholders' Equity Table Of Changes In AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total, Beginning Balance	$ (238)
Other comprehensive income (loss)	6	$ 6
Total, Ending Balance	(294)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total, Beginning Balance	(238)
Adoption of ASU 2018-02 (Note 1)			$ (61)
Amounts reclassified from accumulated other comprehensive income (loss)	5
Other comprehensive income (loss)	5
Total, Ending Balance	(294)
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total, Beginning Balance	(2)
Adoption of ASU 2018-02 (Note 1)			0
Amounts reclassified from accumulated other comprehensive income (loss)	0
Total, Ending Balance	(2)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total, Beginning Balance	(1)
Adoption of ASU 2018-02 (Note 1)			0
Amounts reclassified from accumulated other comprehensive income (loss)	0
Total, Ending Balance	(1)
Pension and Other Postretirement Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total, Beginning Balance	(235)
Adoption of ASU 2018-02 (Note 1)			$ (61)
Amounts reclassified from accumulated other comprehensive income (loss)	5
Total, Ending Balance	(291)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss)	$ 5