Restructuring and Other Charges - Activity and Reserve Balances for Restructuring Charges (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ 26	$ 14	$ 99	$ 30
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Asset retirement obligations					$ 8
Environmental Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					2
Legal Costs [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					$ 4
Stock awards reversal [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges			$ 13