Investment in Unconsolidated Joint Ventures (Wildwood Associates) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) a	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Equity Method Investments [Line Items]
Operating distributions from unconsolidated joint ventures	$ 7,764	$ 8,760	$ 10,296
Company's investment balance	$ 156,388	79,434
Wildwood Associates
Schedule of Equity Method Investments [Line Items]
Ownership percentage of partner in joint venture	50.00%
Operating distributions from unconsolidated joint ventures			2,100
Recognition of deferred income			$ 582
Company's investment balance	$ (1,143)	$ (1,122)
Wildwood Associates | IBM
Schedule of Equity Method Investments [Line Items]
Ownership percentage of partner in joint venture	50.00%
Acres of land available for development or sale (acres) | a	22