Commitments and Contingencies - Environmental Remediation - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Environmental contingencies	$ 39	$ 41
Current reserves for environmental contingencies	1	1
Lake Charles South Facility [Member]
Loss Contingencies [Line Items]
Environmental contingencies	12	12
Natrium West Virginia Facility [Member]
Loss Contingencies [Line Items]
Environmental contingencies	18	18
Calcasieu River Estuary in Lake Charles Louisiana [Member]
Loss Contingencies [Line Items]
Environmental contingencies	$ 3	$ 4