Environmental Commitments and Contingencies - Additional Information 1 (Detail)	9 Months Ended
	Sep. 30, 2015 USD ($)
Key West Florida [Member]
Environmental Commitments And Contingencies [Line Items]
Period of regulatory inactivity	17 years
Costs to resolve liability	$ 50,000
Key West Florida [Member] | Maximum [Member]
Environmental Commitments And Contingencies [Line Items]
Costs to resolve liability	8,000
Pensacola Florida [Member]
Environmental Commitments And Contingencies [Line Items]
Costs to resolve liability	5,000
Winter Haven Florida [Member]
Environmental Commitments And Contingencies [Line Items]
Environmental remediation expense	443,000
Additional remediation costs	100,000
Salisbury Maryland [Member]
Environmental Commitments And Contingencies [Line Items]
Monitoring well remaining maximum cost	$ 5,000