Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Carrying Amount
Financial Assets:
Cash and cash equivalents	$ 71,838	$ 74,961
Mortgage loan receivable	3,289	3,331
Interest rate swap agreements	0	474
Financial Liabilities:
Mortgage notes payable, net	1,058,691	1,235,502
Notes payable to banks, net	543,742	542,880
Interest rate swap agreements	13,769	9,026
Fair Value
Financial Assets:
Cash and cash equivalents	71,838	74,961
Mortgage loan receivable	3,289	3,331
Interest rate swap agreements	0	474
Financial Liabilities:
Mortgage notes payable, net	1,092,792	1,235,553
Notes payable to banks, net	556,675	548,414
Interest rate swap agreements	$ 13,769	$ 9,026