Pensions And Other Postemployment Benefits (Assumed Health Care Cost Trend Rate Reported For Other Postemployment Benefits Plans) (Detail) - Other Postretirement Benefits $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
100 basis point (“bp”) increase in health care cost trend rate - Total Service Interest Cost	$ 1
100 basis point (“bp”) increase in health care cost trend rate - APBO	24
100 bp decrease in health care cost trend rate - Total Service Interest Cost	(1)
100 bp decrease in health care cost trend rate - APBO	$ (21)