Commitments and Contingencies - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014 Plaintiff Cases site	Dec. 31, 2013
Loss Contingencies [Line Items]
Number of cases administratively dismissed or inactive	100
Liable periods	twenty-year
Payments for litigation	$ 1,150,000,000
Accrued environmental obligations approximately	118,231,000	113,636,000
Sites associated with remediation	45
Remediation and related matters possible to estimate costs	$ 158,000,000
Currently not able to estimate a range of costs to sites	5
Number of cases pending	1,130
Number of Plaintiffs Involved in Pending Cases	1,643
Other Litigation
Loss Contingencies [Line Items]
Number of cases administratively dismissed or inactive	8,298