Commitments and Contingencies (Environmental Matters) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Environmetal Remediation Obligations [Line Items]
Accrued environmental liabilities	$ 2,424,000	$ 3,213,000
Site Contingency, Recovery from Third Party of Environmental Remediation Cost	3,100,000	1,100,000
Costs | Second Joint Venture Partner of Former Owner / Operator
Environmetal Remediation Obligations [Line Items]
Ownership responsibility for site investigation and remediation costs (as a percent)	37.50%
Environmental and Other Matters | Sold Parcel
Environmetal Remediation Obligations [Line Items]
Remediation cost, expected cost	100,000
Environmental and Other Matters | Costs | Former Owner / Operator
Environmetal Remediation Obligations [Line Items]
Ownership responsibility for site investigation and remediation costs (as a percent)	75.00%
Environmental remediation expense	4,500,000
Environmental and Other Matters | Costs | First Joint Venture Partner of Former Owner / Operator
Environmetal Remediation Obligations [Line Items]
Ownership responsibility for site investigation and remediation costs (as a percent)	37.50%
Environmental and Other Matters | Costs | HHEM and H&H
Environmetal Remediation Obligations [Line Items]
Ownership responsibility for site investigation and remediation costs (as a percent)	25.00%
Environmental loss contingencies, payments	1,000,000
Environmental remediation expense	1,500,000
Environmental and Other Matters | Industrial Property
Environmetal Remediation Obligations [Line Items]
Accrual for environmental loss contingencies	$ 200,000