Restructuring - Restructuring Activities and Related Reserves (Detail) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Reserve balance	$ 3	$ 3	$ 3
Charges (gain)	1	(9)	1
Accrual for deposit on sale of land	(3)		(4)
Costs charged against assets / (liabilities)		1
Cash (paid) received	1	8	3
Reserve balance	2	3	3
Severance and Employee Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	1	1	1
Charges (gain)		1
Cash (paid) received	(1)	(1)
Reserve balance		1	1
Environmental Remediation [Member]
Restructuring Cost And Reserve [Line Items]
Reserve balance	2	2	2
Charges (gain)	1
Cash (paid) received	(1)
Reserve balance	2	2	2
Asset Sales [Member]
Restructuring Cost And Reserve [Line Items]
Charges (gain)		(11)
Accrual for deposit on sale of land	(3)		(4)
Costs charged against assets / (liabilities)		2
Cash (paid) received	$ 3	9	4
Other [Member]
Restructuring Cost And Reserve [Line Items]
Charges (gain)			1
Cash (paid) received			$ (1)
Asset Impairment and Accelerated Depreciation [Member]
Restructuring Cost And Reserve [Line Items]
Charges (gain)		1
Costs charged against assets / (liabilities)		$ (1)