Covenants and Events of Default (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	$ 225,922	$ 229,498	$ 240,715
Covenant Compliance	As of September 2017, we were in compliance with the covenants contained in our note purchase agreement governing our 2019 Notes and Credit Agreement. We are not aware of any non-compliance by any of our unconsolidated real estate entities with the covenants contained in their debt agreements.
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit agreement	$ 30,000	30,000
Term Loan [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	91,300
Long term portion of term loan	86,300	90,000	91,300
Short term portion of term loan	5,000	5,000	5,000
Senior Notes [Member] | 2019 Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 120,000	120,000	160,000
Debt Instrument, Interest Rate, Stated Percentage	6.11%
Long-term Debt, Excluding Current Maturities	$ 110,000	110,000	150,000
Scheduled current period payments	40,000	40,000	40,000
Senior Notes [Member] | 2019 Notes [Member] | Long-term Debt
Debt Instrument [Line Items]
Scheduled current period payments	30,000	30,000	30,000
Senior Notes [Member] | 2019 Notes [Member] | Current Maturities of Long-term Debt
Debt Instrument [Line Items]
Scheduled current period payments	10,000	$ 10,000	$ 10,000
Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	291,300
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	200,000
Term Loan Sublimit for Letters of Credit [Member] [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 100,000